states at 300K. Photoluminescence‐based techniques are abundantly used in the halide‐perovskite solar cell literature to study recombination in the bulk and at interfaces. concentration gradient exists – they want to move, or spread out, until an equilibrium concentration is achieved. 1018 cm-3 nD = 1015 cm-3 …. PHGN/CHEN/MLGN 435/535: Interdisciplinary Silicon Processing Laboratory 1/C2 vs V Assumes an abrupt junction - Schottky, p +n or n p v C-2 Slope gives carrier Concentration x-intercept give V bi What if the line isn’t straight?. 8 x 1019 cm3 and Ny = 1. carrier mobility to calculate carrier concentration vs depth. 05 Part - C (Problem Solving and Critical Thinking Questions) 1 Find carrier concentration of an intrinsic semiconductor of band gap 0. For an intrinsic semiconductor The number of carriers are generated by thermally or electromagnetic radiation for a pure s/c. 12 eV Relative Permittivity: r = 11. At 300 K the generally accepted value for the intrinsic carrier concentration of silicon, n i, is 9. 8 meV to 560 meV, which is one-half of the. First of all, one can calculate the intrinsic carrier concentration from the formulas given in the problem: T (eV)( K) E g n i (cm 3) 298 1. Assume the intrinsic carrier concentration of silicon to be 1. Notice the similarity between Figure 3 & 4, as the electrons and holes are the source of conductivity in intrinsic semiconductors. Compute the intrinsic carrier concentration at room temperature. com A Introduction This paper contains information on the resistivity, mobility, and diffusivity of electrons and holes in silicon. What is the product of the new electron and hole concentration?. 5 m A at room temperature 300 o K. Sketch And Explain How The Electron, Intrinsic, And Hole Carrier Concentrations, And Fermi Level, Vary With Temperature In An N-type Semiconductor. 0 x 1019 cm-3. (a)Draw the energy band diagram of the junction at thermal equilibrium. (a) Calculate the resistivity at T = 300 K of intrinsic (i) silicon, (ii) germanium. 31 eV (B) goes up by 0. Calculate the current density that flows in the x-direction. This type of impurity is called donor. 5 1010 cm-3 at T=300K In silicon at T=300K , the mobilities of electrons n 1350 cm2 /V. ni = intrinsic carrier concentration. I don't know where you got this 10^(-3) value for the resistivity (which should be in ohms-m), it is more confusing when you don't use units. The metallurgical base width is. 27eV above the valencebandenergy. This is known as the intrinsic carrier concentration. For silicon at 300K, n i = 1. EXAMPLE 1 Calculate the probability that a quantum state in conduction band at E = EC + kT/2 is occupied by an electron and calculate the thermal equilibrium electron concentration in Silicon at T = 300K. Silicon is doped with boron to a concentration of 410# 17 atoms cm3. 38 X 10 19 (T/300) 2 exp(- 6884/T) Here T = temperature The intrinsic carrier concentration at 300K is 1. 45 x 10^10 cm^-3. Charge carrier density, also known as carrier concentration, denotes the number of charge carriers in per volume. Carrier Concentrations in Intrinsic Si •The “band-gap energy” E g is the amount of energy needed to remove an electron from a covalent bond. Therefore, the Fermi level for the intrinsic semiconductor lies in the middle of forbidden band. Important parameters Resistance measurement. electron gas of silicon with intrinsic conductivity. For example, silicon is a semiconductor, the intrinsic carrier concentration is about 1 x 1010 cm-3, at room temperature. Be very careful about units. 5E10 cm-3…intrinsic carrier concentration for silicon N d = 5E15 cm-3…donator concentration at T = 300 K for silicon N a = 1E17 cm. Problem 3(1+2+1p): Consider a p-type Si at T = 300 K doped at Na = 5 x 10 15 cm-3. The illustration below is a simplified sketch; the actual crystal structure of silicon is a diamond lattice. Intrinsic carrier concentration of Silicon is 1. 10 For an intrinsic material, the Fermi level E F is located very close to the middle of the band-gap. Relative pennittivity of silicon cs/ co 11. 044 eV EΓ1 = 3. 22E+19 Density of states in valence band, N V (cm-3)€ 1. 4 x 1013 cm-3 b) Extrinsic. Then the excess hole concentration profile throughout the sample will be given by δp(x) = ∆p n exp(−x L p) (a) (10 pts. In SI units, it is measured in m −3. Density n(E) is given by product of density states N(E) and a probability of occupying energy range F(E). pdf), Text File (. The device structures may be specified by the user, or from the output of a process simulator such as Athena. Abstract Since the measurements of Morin and Maita in 1954 it is customary to consider n i = 1. , and Zhao, J. Far away from the pn-junction the carrier concentration in the n-region is given by: The carrier concentration in the p-region is given by: Energy band diagram and carrier concentration for a silicon pn-junction at zero bias. • mean energy loss per flight path of a mip dE/dx = 3. Calculate the probability that a state in the conduction band is occupied by an electron and calculate the thermal equilibrium electron concentration in silicon at T= 300 K. 18 m 0; Holes: m∗p = 0. (a) Determine the concentration of electrons and holes at 300K in intrinsic material. For silicon at 300K, n i = 1. [6 Marks] (b) A Sample Of Silicon At 300 K Is Doped With A Phosphorus Concentration Of 5 X 1015 Cm", Which Acts As A Donor. Assume Fermi Energy is 0. In this chapter I will be studying the density of states effective masses and the carrier concentration masses of relaxed Si1_,Gex and strained Si1_,Gex on relaxed SisGe, , for. 5 1010 cm-3 at T=300K In silicon at T=300K , the mobilities of electrons n 1350 cm2 /V. for the concentration of the free electrons as well as that of the hole: B. To obtain the electron density (number of electron per unit volume) in intrinsic semiconductor , we must evaluate the electron density in an incremental energy range dE. If you want to know the carrier mobility that we used for a given point, you can calculate if from the numerical listing of. 8 X 10 Cm And Ny = 1. The separation of positive ions and negative electrons induces an E-field in +x direction to oppose the diffusion process. The transistor dopings are , , and. 374 10 407 54. Notice the similarity between Figure 3 & 4, as the electrons and holes are the source of conductivity in intrinsic semiconductors. For an intrinsic semiconductor The number of carriers are generated by thermally or electromagnetic radiation for a pure s/c. What is the donor concentration Nd? For Si at 300K. i = np, calculate kT in eV and use the following constants: hc = 1. Homework Set #1: 1. A silicon sample maintained at T=300K is characterized by the energy band-diagram below: a) Do equilibrium conditions prevail? How do you know? Since the Fermi level (EF) is constant with position, equilibrium conditions prevail. To calculate silicon carrier concentration values, we use carrier mobility values derived from Thurber, Mattis, Liu, and Filliben, National Bureau of Standards Special Publication 400-64, The Relationship Between Resistivity and Dopant Density for Phosphorus-and Boron-Doped Silicon (May 1981), Table 10, Page 34 and Table 14, Page 40. 849 eV (10) above E v and E Fp = E i − ln δn n i ≈ 0. The mass action equilibrium for electrons and holes also applies to doped semiconductors, so we can write: \[n \times p = n_{i}^{2} = 10^{20} cm^{-6} \: at \: 300K\]. In our intrinsic semiconductor, n = p = n i. 42 eV (300 ) 7. 429 eV in the n-side at thermal equilibrium (T - 300K). Silicon is doped with 2. 5x1010 cm-3 at 300K is the intrinsic carrier concentration in pure silicon) = (2q si N A)/C ox is the body-effect coefficient (impact of changes in V SB) ( si =1. Free electron concentration in donor - doped semiconductors For Si and other semiconductors, the typical doping levels are: ND = 1015 cm-3 …. 23 x 1015 cm-3 K-3/2. (a)Find the position of the Fermi level E F. Determine the concentration of majority carriers in the absorber side. Intrinsic Carrier Concentration S. (c) Determine the neutral base width for this bias. Calculator. Conversely, the hole concentration under reverse bias is much smaller than the equilibrium value. f) On the same set of coordinates, make a rough sketch of the electron drift-current density and the shines on an intrinsic sample of GaAs of. with rather old measurements is perceptibly higher than the calculated values of n, above about 400 K. Intrinsic carrier concentration of silicon is. Find the intrinsic carrier concentration at 300K and 400K 1. where or are the equilibrium concentrations of P or N type mobile charge carriers (i. What are the. 45 x 10^10 cm^-3. For pure silicon, then n2 N N exp(E /kT) i c V G Thus n i = 1 x 1010cm-3 Similarly the Fermi level for the intrinsic silicon is, E i E V (E C E V )/2 (1/2)kT ln(N V /N C) Where we have used Eito indicate intrinsic Fermi level for Si. 8 x 1019 cm-3. As with any density, in principle it can depend on position. 25eV below conduction band and Nc = 2. Welcome to the mobility calculator. EXAMPLE 1 Calculate the probability that a quantum state in conduction band at E = EC + kT/2 is occupied by an electron and calculate the thermal equilibrium electron concentration in Silicon at T = 300K. Below is a table for the intrinsic electron concentration for three different temperatures. (b) Repeat part (a) if the Si is doped with boron atoms at a concentration of 1015cm-3. 5 1010 cm-3 at T=300K In silicon at T=300K , the mobilities of electrons n 1350 cm2 /V. Table: Effective mass values for Ge, Si and GaAs. Carrier concentration in thermal equilibrium •Carrier concentration vs. 5 x 10^10 per. • mean energy loss per flight path of a mip dE/dx = 3. •The concentration of conduction electrons in intrinsic silicon, n i, depends exponentially on E g and the absolute temperature (T): 1 10 / at 600K 1 10 / at 300K / 2 5. Calculate the position of Fermi level at 300K for germanium crystal containing 5x1022 arsenic atoms /m 3. P-N junctions. We first calculate in terms of the chemical potential the number of electrons excited to the conduction band at temperature T. p hole concentration (number h+ / cm3) n electron concentration (number e- / cm3) n i intrinsic carrier concentration N D Donor concentration (number donors / cm 3) N A Acceptor concentration (number acceptors / cm 3) k b Boltzmann's constant 1. (2p) How large is the electron and hole concentration in the p-type. In intrinsic semiconductor, when the valence electrons broke the covalent bond and jumps into the conduction band, two types of charge carriers gets generated. Consider a piece of pure silicon 100 µm long with a cross-sectional area of 1 µm2. of silicon that is uniformly and non-degenerately doped. 8 ×106 cm-3: Intrinsic resistivity (300K) 3. 5 x 10 10 cm -3. 8 x 1019 cm-3. Resistivity: 1. Understand CO 2 AHSB13. ii‐ The Hall Electric field. (Freeze out region) When the temperature is increased so high that the intrinsic carrier conc. Read 3 answers by scientists with 5 recommendations from their colleagues to the question asked by Asrar Asghar on May 7, 2020. (b) At this bias, determine the minority-carrier hole concentration at. Intrinsic carriers concentration in silicon is given by, n i = 9. Hence the electron-carrier concentration is equal to the hole-carrier concentration. 45x1010 cm-3, at room temp. Achieving high and low temperature regimes. Practically in pure or intrinsic silicon crystal the number of holes (p) and electrons (n) are equal to each other, and they are equal to intrinsic carrier concentration n i. The separation of positive ions and negative electrons induces an E-field in +x direction to oppose the diffusion process. Impurity Profiles for Diffusion in Common Semiconductors Background (click to expand) Basic diffusion mechanisms and profiles for dopants and impurities into semiconductors are based on a group of equations known as Fick's Laws. [6 Marks] (b) A Sample Of Silicon At 300 K Is Doped With A Phosphorus Concentration Of 5 X 1015 Cm", Which Acts As A Donor. Electron mobility at this. 45x1010 cm-3 for silicon @ T = 300oK. Notes: Intrinsic carrier density refers to total number of carriers in intrinsic semiconductors. 1018 cm-3 nD = 1015 cm-3 …. Semiconductors 6. ni = intrinsic carrier concentration. Assume the detector breaks down when the bias voltage, V b, exceeds 50 mV. The intrinsic carrier concentration depends on mainly; bandgap, Eg. Calculate the V T of a MOS capacitor where we deposit high-k gate dielectric, HfO 2, whose relative dielectric constant is 25 on a novel p-type semiconductor whose electron a nity is 4eV, band gap = 1. Calculate the intrinsic carrier concentration, n i, of silicon at -40, room temp, and 85 centigrade. 327, hole mass 0. 45 x 10 10 cm-3 at 300K Germanium (E g = 0. 8 x 1019 cm3 and Ny = 1. Diodes: For this problem, you may use an intrinsic carrier concentration n i = 1:5 1010 1=cm3 at 300K and n i = 0:73811=cm3 at 150K, an electrical permittivity of silicon si = 10 12 F=cm, and a diode cross sectional area A D = 0:5µm2. Assume Fermi Energy is 0. 45e10 cm-3: Intrinsic Debye Length: 24 um: Intrinsic Resistivity: 2. 00e12 Intrinsic carrier concentration in 1/m^3 of Gallium(III) arsenide. The intrinsic concentration of silicon is given by ni= n0 µ T 300 ¶3/2 exp µ −VG 2VT ¶ If VG=1. Thus lattice scattering lowers the carrier mobility more and more at higher temperature. 25 x 10 15 atoms/cm 3 , the equilibrium electron and hole densities are: n 0 = 1. No matter what happens with doping, however, the one equation that always remains true for extrinsic semiconductors is \[np = n_i ^2 \label{2}\] where n is the electron concentration, p is the hole concentration, and\(n_i\) is the intrinsic carrier concentration (the concentration had the semiconductor not been doped). Intrinsic Carrier Concentration Semi-conductor behaviour is defined by the conductivity due to the electrons crossing the (narrow) band gap due to thermal excitations. Problem 1: In a p-nt junction silicon solar cell, the Fermi level position with respect to intrinsic energy level is 0. Free electron concentration in donor - doped semiconductors For Si and other semiconductors, the typical doping levels are: ND = 1015 cm-3 …. i = np, calculate kT in eV and use the following constants: hc = 1. Calculate the temperature at which there is a 10−8 probability that an energy state 0. Recitation 2: Equilibrium Electron and Hole Concentration from Doping Here is a list of new things we learned yesterday: 1. Charge carrier density, also known as carrier concentration, denotes the number of charge carriers in per volume. As compared to Si, the Phosphorus has one extra valence electron which, after all bonds are made, has very weak bonding. They are always there, because they are the original carriers or we can call them as intrinsic carriers. A silicon wafer is n-type doped with arsenic atoms of a concentration of N D = 1015cm 3, N D= 10 18cm 3 and N D= 10 20cm 3. b) The temperature at which the intrinsic concentration n i exceeds the impurity density by a factor of 10 (for each materials). 01 x 1010 cm-3 intrinsic carrier density at 300K* (‘old’ value: 1. Find Concentration. Find a concentration of electrons in the conduction band of intrinsic (undoped) Si at T= 77 K if at 300 K ni = 1. Consider a Silicon material doped with 3x1016cm-3 donor atoms. The transistor dopings are , , and. 7~10~'~ and 8. Sketch the band diagram for silicon and add the Fermi and the intrinsic energy levels at room temperature (300K). carrier concentrations in the different regions of the device. Illumination produces a constant excess carrier generation rate, Go,in the region - L< X < +L. Calculate n, p, and at 300 K. ni = intrinsic carrier concentration. They are free electrons and holes. AAeB cm −3 DOPING TYPE (4 points possible) The next four problems are based on the same data: A piece of silicon is doped with 8×10 10 atoms/cm 3 of Boron and 3×10 10 atoms/cm 3 of Phosphorus. Assuming a band gap of 1. 39, electron mobility 0. Read 3 answers by scientists with 5 recommendations from their colleagues to the question asked by Asrar Asghar on May 7, 2020. A silicon wafer is n-type doped with arsenic atoms of a concentration of N D = 1015cm 3, N D= 10 18cm 3 and N D= 10 20cm 3. 38E-23 J/K …Boltzmann constant ε 0 = 8. (b) At this bias, determine the minority-carrier hole concentration at. 2·E5 Ω·cm: Effective conduction band density states: 3. A silicon sample maintained at T=300K is characterized by the energy band-diagram below: a) Do equilibrium conditions prevail? so that sketching the carrier concentration profiles becomes easy. 42 nm-1 (measured from band edge). third free carrier. 6 x 10-6 K-1: Effective Density of States in the. (b) If rectangular semiconductors bars are fabricated using the materials in part (a), determine the resistance of each bar if its cross-sectional array is 85 µm and length is 200 µm. 66 eV): ni= 2. 1000 times greater than the carrier concentration of bulk GaAs, but close to the carrier concentration of bulk sili-con (1:45x1010cm 35). The results for carrier concentration and mobility and other microscopic parameters are summarized in the fol-lowing table: 300K 77K Units R 2 2070 164:7 136. At What Temperature The Carrier Concentration In Intrinsic Silicon Is 2e 13 Cm'? Calculate Resistivity Of This Silicon. ni = intrinsic carrier concentration. Effective mass is m∗ e/m 0 = 0. 52 x 10 10 electrons/cm3 (10. 026eV; the energy reference will be taken at the highest occupied level of the valence band (E V =0eV). Ans: We can use the same equation as above to calculate the carrier concentration. Calculate the intrinsic carrier density for SiC at T= 300K. at 300K? Is this ntype or p- -type doped silicon? Problem 3. A piece of n-type or p-type silicon is electrically neutral; thecharge of majority free carriers are neutralized by the bound charges associated with the impurity atoms. 3 or calculate it using the following empirical relationships for silicon: n = 65 + 1265 1 + N 8:5 1016 0:72 p = 48 + 447 1 + N 6:3 1016 0:76 P3 At which concentration of electrons nthe GaAs conductivity at room temperature is minimal? Take the intrinsic carrier concentration from Table 4. Both electron and hole mobilities are positive by definition. Intrinsic Semiconductor vs. Electron effective masses (= 0. Theoretical calculations reveal that the mobility in non-polar semiconductors, such as silicon and germanium, is dominated by acoustic phonon interaction. In intrinsic or pure semiconductor, the number of holes in valence band is equal to the number of electrons in the conduction band. Knowledge of intrinsic carrier concentration, effective equilibrium minority carrier concentration, minority carrier mobility, and effective carrier lifetime obtained by theoretical and. Calculate the intrinsic carrier concentration in Ge at 300K (cm −3). 0·10 10 cm -3 to be more realistic and of higher precision. • Intrinsic (undoped) Semiconductors – intrinsic carrier concentration≡n i = 1. Find Concentration. Draw the energy band diagram with the quasi Fermi levels at 300K. Calculate the probability that a state in the conduction band is occupied by an electron and calculate the thermal equilibrium electron concentration in silicon at T= 300 K. (b) If doping with donor atoms to give an impurity concentration of 1022 atoms / m3 is carried out for silicon crystal of part (a): Calculate the majority and minority carrier's concentrations and the resistivity of the new crystal at room temperature. 12 eV EL = 2. 27eV above the valence band energy. Calculate the intrinsic carrier concentration n i at T = 200 K, 400 K, and 600 K for (a) silicon, (b) germanium, and (c) gallium arsenide. Intrinsic Carrier Concentration Contains an insignificant concentration of impurity atoms Under the equilibrium conditions, for every electron is created, a hole is created also n = p = ni As temperature is increased, the number of broken bonds (carriers) increases As the temperature is decreased, electrons do not receive enough. Question: Question5 : (4 Marks) Calculate The Intrinsic Carrier Concentration (n) In Silicon At: T = 810 K. The Fermi level if. 72 10 cm) 2 0. The concentration of these carriers is known as intrinsic carrier concentration. 1 3 5 m 2 / V s and 0. 8 X 10 Cm And Ny = 1. 12 EV N = 2. You can use scientific notation, as in A. Notes: Intrinsic carrier density refers to total number of carriers in intrinsic semiconductors. 8 x 1019 cm and Nv= 1. Considering silicon is a group IV element that has four valence electrons. Assuming a band gap of 1. Practically in pure or intrinsic silicon crystal the number of holes (p) and electrons (n) are equal to each other, and they are equal to intrinsic carrier concentration n i. An ideal silicon pn junction at T=300K is under forward bias. com A Introduction This paper contains information on the resistivity, mobility, and diffusivity of electrons and holes in silicon. Hint: at 300K, kT=0. If the electron mobility is 1350cm2/Vs, I looked up in a table to find the corresponding hole mobility in silicon and it's about 490cm^2/Vs. Remember CO 2 AHSB13. Total Impurity Concentration (cm-3) Mobility ( cm 2 /V-sec ) Electron Mobility Hole Mobility Carrier Mobility for Silicon, 300K 280 300 320 340 360 380 400 10 9 10 10 10 11 10 12 10 13 Absolute Temperature (K) Intrinsic Carrier Density (per cm 3) Intrinsic Silicon Carrier Density. would si doped with 1015atoms/cc of. Intrinsic Carrier Concentration Contains an insignificant concentration of impurity atoms Under the equilibrium conditions, for every electron is created, a hole is created also n = p = ni As temperature is increased, the number of broken bonds (carriers) increases As the temperature is decreased, electrons do not receive enough. Some results are shown in Fig. Draw the Thévenin and Norton equivalents for the port labeled vo and calculate the component values. 239 × 10−4 eV-cm and mc2 = 0. 45 x 10 10 cm-3 at 300K Germanium (E g = 0. Calculate the intrinsic carrier concentration (ni) in silicon at: T = 810 K. , 70, 846-854 1991. Properties of Si, Ge, and GaAs at 300K Energy Gap at 300K (eV) 1. ENSC 224 HOMEWORK #1 DUE: Monday September 28, 2015 at 12 noon Fall 2015 Please note that unless you show work in the derivations and solutions you will get no credit for the answers. 6 * 10 19 C. The carrier lifetimes are τ n = τ p = 10−7 sec. 044 eV EΓ1 = 3. Intrinsic Semiconductor. The density of electrons in the conduction band equals the density of holes in the valence band. 5×1010/cm3 Intrinsic Si Electron Mobility: µ n = 1350 cm2/V ·s Intrinsic Si Hole Mobility: µ p = 480 cm2/V ·s 10 15 10 16 10 17 10 18 10 19 10 20 0 200 400 600 800 1000 1200 1400 1600 1800. (a) Silicon is uniformly doped with 1022 phosphorus atoms/m3. 52 x 10 10 electrons/cm3 (10. The hole mobility is µ p = 480 cm2/Vs. Saha HO #2: ELEN 251 - Semiconductor Physics Page 3 The product of the number of e−and holes is given by: ∴ n i ≅1. Welcome to the recombination calculator. 5 × 1013/cm3at300K. Determine the excess minority carrier concentration as a function of time for 0≤t≤∞. Determine the equilibrium electron and hole concentration inside a uniformly doped sample of Si under the following conditions: T = 450 K, NA = 0 cm-3, ND = 1014 cm-3 2. carrier concentration. If you are not already familiar with it, read the Introduction page of this applet. Carrier densities given the doping density. Thus lattice scattering lowers the carrier mobility more and more at higher temperature. resistivity=1/(n*q*u1+p*q*u2)。 here n is electron density,p is hole density,in this situation,n=p=intrinsic carrier concentration. Use the intrinsic concentration of the semiconductor and the given electron concentration to determine E F. Assuming complete impurity ionization, the equilibrium electron and hole concentrations are. ppt), PDF File (. Of What Type Is This Silicon And What Is Donor Concentration In It? 3. 5 x 1010 cm-3. (a)Determine the position of the Fermi level with respect to the intrinsic Fermi level. Assume The Bandgap Energy Of Silicon Is 1. ECE 340 Lecture 6 Intrinsic Material, Doping, Carrier Concentrations. concentration gradient exists – they want to move, or spread out, until an equilibrium concentration is achieved. You can use scientific notation, as in A. , the number of electrons in the conduction band (and also the number of holes in the valence band) per unit volume in a semiconductor that is completely free of impurities and defects. 04 X 100 Cm-ar T = 300 K Pics De Question 6: (4 Marks) Calculate The Density Of States Per Unit Volume. Using the system, thermal boron diffusion from the BSG film is investigated and confirmed in terms of process stability for surface property before BSG deposition and BSG thickness. 2 Doped Semiconductors The intrinsic silicon crystal described above has equal concentrations of free electrons and holes, generated by thermal generation. The Fermi level if. with no other types of atoms within the crystal. This leads to the resistivity calculations shown in Figures 3 and 4, where the inverse of the product between ionized-impurity concentration and carrier mo-bility has been calculated as a function of temperature at different total doping concen-trations. Assume The Bandgap Energy Of Silicon Is 1. (b) Calculate the intrinsic carrier concentration at 300K in a semiconductor which has a single valence band maxima given by E= E v ( h2k2=2m 0) and eight conduction band minima in the h111idirections with E= E c + 2 h2(k k 0)2=m 0 where k 0 = ( a; a; a), E c E v = 1eV and m 0 is the free electron mass. 4 can be solved for V OC,Implied: ( ) lnk T 2 ( ) / ), 0 i B OC implied p n n n e V T '' (5) In this paper, p-type material is considered and p 0 refers to the concentration of ionized acceptor impurities. Determine its n or p character if the intrinsic carrier concentration of Ge at room temperature is n i = 2. c) The equilibrium minority-carrier concentrations in each materials at 300 K. A new experimental measurement of 1. 26eV above Ev at 300K. For example, silicon is a semiconductor, the intrinsic carrier concentration is about 1 x 1010 cm-3, at room temperature. 8 x 1019 cm3 and Ny = 1. q is unit charge. The intrinsic carrier concentration in silicon at 27 ᵒC is n i =1. Determine the concentration of majority carriers in the absorber side. states at 300K. 6173(10 5) eV/ K) Of course, the silicon is n-type since phosphorus is a donor dopant. Convention: The potential of pure intrinsic Silicon is used as the reference value and assumed to be equal to zero. 04 x 1019 cm-3 Silicon Band Gap Eo 1. The intrinsic carrier concentration, n_i, is equal to the product of the electron concentration n, and the hole concentration p. 12 eV Relative Permittivity: r = 11. Assume The Bandgap Energy Of Silicon Is 1. 38 x 10-23 joules / K T temperature K E g Energy gap of semiconductor eV J Current density A / cm 2 E. Silicon (E g = 1. 0258 V (at 300K) Relative dielectric constant of silicon, K s = 11. The hole mobility is defined by the same equation. Remember CO 2 AHSB13. Si: E A E V = 45meV SiC: E G= 2:3eV, N V = 1:8 1019cm 3, N C = 3 1019cm 3, E A E V = 260meV 14. 044 eV EΓ1 = 3. Intrinsic density and the np product. 2 10 exp 15 3 10 3 15 3 / 2. The conductivity of intrinsic semiconductor is given by. 2 ev at 298°K intrinsic carrier concentration in silicon increases with the increase of temperature. The intrinsic carrier concentration is a very strong function ot temperature. n Nsub q kT. As the temperature is increased, the number of broken bonds (carriers) increases because there is more thermal energy available so more and more electrons gain enough energy to break free. Think about why this is higher than the number discussed for Si at comparable temperatures. 68 24 2250 Intrinsic resistivity (Ω-cm) 47 23 10. (7) 2 a) A Silicon bar of 100 cm long and 1 cm2 cross sectional area is doped with 1017Arsenic atoms/cm3. 16 eV above Ev(Valence band edge), and Ef is 0. For pure silicon, then n2 N N exp(E /kT) i c V G Thus n i = 1 x 1010cm-3 Similarly the Fermi level for the intrinsic silicon is, E i E V (E C E V )/2 (1/2)kT ln(N V /N C) Where we have used Eito indicate intrinsic Fermi level for Si. Abstract Since the measurements of Morin and Maita in 1954 it is customary to consider n i = 1. 34×1013 cm−3)(3900+1900)cm2V−1s−1 = 0. 044 eV EΓ1 = 3. carrier mobility to calculate carrier concentration vs depth. 1 cm long and 100µ m2 in a cross – sectional area has majority carrier concentration of 5 * 1020 / m3 and carrier mobility is 0. 068 m0: Intrinsic electron concentration: 1. 15 m 2 /Vs, hole mobility 0. The General Properties of Si, Ge, SiGe, SiO2 and Si3N4 June 2002 The following table summarizes many of the basic physical properties of Silicon, Germanium, and Silicon Germanium at different concentrations. Calculate: i‐ The Hall voltage. 04x1019cm-3, and Egap(300K) = 1. EXAMPLE 1 Calculate the probability that a quantum state in conduction band at E = EC + kT/2 is occupied by an electron and calculate the thermal equilibrium electron concentration in Silicon at T = 300K. Notice the similarity between Figure 3 & 4, as the electrons and holes are the source of conductivity in intrinsic semiconductors. Consider silicon at T = 300 K doped with phosphorous at a concentration of Nd = 1016 cm-3 and ni = 1. would si doped with 1015atoms/cc of. 0∗1016 arsenic atoms per cm3. This calculator gives the intrinsic carrier concentration in a semiconductor material. As the temperature is increased, the number of broken bonds (carriers) increases because there is more thermal energy available so more and more electrons gain enough energy to break free. 4 x 1013 Ge. These are given by the following two equations: 3. 38xlO-23 J K1 Thennal voltage at T = 300K kT/q 0. Intrinsic Carrier Concentration Semi-conductor behaviour is defined by the conductivity due to the electrons crossing the (narrow) band gap due to thermal excitations. Thermal voltage, kT/q = 0. The conductivity of intrinsic semiconductor is given by. ni = intrinsic carrier concentration. The intrinsic carrier concentration depends on mainly; bandgap, Eg. 04 x 1019 cm-3 at T = 300 K. Calculate the intrinsic carrier concentration in silicon at T 250K and T 400K. EXAMPLE 1 Calculate the probability that a quantum state in conduction band at E = EC + kT/2 is occupied by an electron and calculate the thermal equilibrium electron concentration in Silicon at T = 300K. To calculate the position of the intrinsic Fermi level with respect to the center of the bandgap in silicon at T = 300 K. Conversely, the hole concentration under reverse bias is much smaller than the equilibrium value. b) Sketch the electrostatic potential V(x) inside the semiconductor as a function of x. 617 x 10-5 eV/ K or 1. 22E+19 Density of states in valence band, N V (cm-3)€ 1. Intrinsic carrier concentration. Walkthrough for Chapter 1, Problem 3P Walkthrough video for this problem:. Fifty years of silicon for semiconductor device applications is the milestone. 8 x 1019 cm-3. Temperature control. Intrinsic Carrier Concentration Semi-conductor behaviour is defined by the conductivity due to the electrons crossing the (narrow) band gap due to thermal excitations. 5 x 1010 cm-3. Calculate n, p, and at 300 K. For an intrinsic semiconductor The number of carriers are generated by thermally or electromagnetic radiation for a pure s/c. Hole Concentration And Acceptor Concentration In A Silicon Sample Are 3e5 Cm3 And Se16 Cm3 Respectively. P-N junctions. There are lots of available states (energy E levels) here. intrinsic carrier concentration, n i. Find the equilibrium electron concentration n 0, hole concentration p 0, and Fermi level E F with respect to the intrinsic Fermi level E i and conduction band edge E C. 5×1010/cm3 Intrinsic Si Electron Mobility: µ n = 1350 cm2/V ·s Intrinsic Si Hole Mobility: µ p = 480 cm2/V ·s 10 15 10 16 10 17 10 18 10 19 10 20 0 200 400 600 800 1000 1200 1400 1600 1800. hin an intrinsic semiconductor] 2. s and of holes p 480 cm /V. Can any please help me in solving the following two questions Q1 A Si sample is doped with 10^16 per cm cube boron atoms and a certain number of shallow donors. Of What Type Is This Silicon And What Is Donor Concentration In It? 3. Our aim is to adapt the expression for in a free electron system to be appropriate for electrons (holes) in a semiconductor. Total Impurity Concentration (cm-3) Mobility ( cm 2 /V-sec ) Electron Mobility Hole Mobility Carrier Mobility for Silicon, 300K 280 300 320 340 360 380 400 10 9 10 10 10 11 10 12 10 13 Absolute Temperature (K) Intrinsic Carrier Density (per cm 3) Intrinsic Silicon Carrier Density. 3) Where: Nsub is the impurity concentration of the. Read 3 answers by scientists with 5 recommendations from their colleagues to the question asked by Asrar Asghar on May 7, 2020. 239 × 10−4 eV-cm and mc2 = 0. 8 x 1019 cm-3. [6 Marks] (b) A Sample Of Silicon At 300 K Is Doped With A Phosphorus Concentration Of 5 X 1015 Cm", Which Acts As A Donor. carrier concentration. Intrinsic Ionization 1000/T (K)-1 1011 1013 1012 1017 1016 1015 14 n 0 (cm-1) Figure 2. 2 eV [click image to enlarge]. Electrons: m∗ n = 1. CONDUCTIVITY AND THE HALL EFFECT 1. 45 × 1010 cm−3. Practically in pure or intrinsic silicon crystal the number of holes (p) and electrons (n) are equal to each other, and they are equal to intrinsic carrier concentration n i. (a) (5 pts. a)Calculate the intrinsic carrier density ni of Silion at T = 280K. The properties of electronic subsystem are determined within the framework of the continuum approach using the quantum statistics of electron gas and Fermi-Dirac integrals in an arbitrary degeneracy range of the electron gas with a temperature change from 300K to 2000K. 8 x 1019 cm-3. inverse temperature 1/T(K) Thermally activated Intrinsic carriers N(carriers) = N(dopants) Activation of dopants Region of Functional device n e. A silicon sample is doped with 1016 phosphorus atoms/cm3. This is only true at thermodynamic equilibrium, and is a consequence of the law of mass action. 1 eV Intrinsic carrier concentration of Si at 300K n i 10 10cm-3. cm-3 and its atomic mass is 28. Calculate the intrinsic density and the Fermi level position for the following temperatures: 27°C, 127°C and 227°C. 60 eVabove the Fermi energy level is occupied by an electron. 04x1019cm-3, and Egap(300K) = 1. 026 V Effective density of states Nc 2. This makes me wonder if they did not leave that factor out of the model equation and thus we are all getting results that very "significantly" from the text. Thermal voltage, kT/q = 0. Simultaneously, a built-in electrical field is created between the elec-trodes. Welcome to the recombination calculator. 8 x 1019 cm-3. A proxy for the electron concentration is resistivity. 1 3 5 m 2 / V s and 0. Temperature 19 At room temperature, all the shallow dopants are ionized. Assuming complete ionization, find out the resistivity of the sample at 300K considering the electron mobility in silicon to be 1350 cm2/V-sec and the hole mobility 450cm2/V-sec. 8 credit points) A silicon wafer is doped with 1016 phosphorus atoms/cm3. Assume that the Fermi energy is 0. 8 Boltzmann's constant k 8. 582 X 1016cm—3 n z NDe And from Rockett's equation 2. Notice the similarity between Figure 3 & 4, as the electrons and holes are the source of conductivity in intrinsic semiconductors. Intrinsic carrier concentration of silicon is. Sketch the band diagram for silicon and add the Fermi and the intrinsic energy levels at room temperature (300K). 1, find the position of the Fermi energy in intrinsic Si, Ge and GaAs with respect to the middle of the bandgap (Eg/2). 45) § µ e 1400 cm2/Vs electron mobility (@ low fields) § µ h 480 cm2/Vs hole mobility (v = µE) § E. Following Altermat et ai. At 300 K the generally accepted value for the intrinsic carrier concentration of silicon, n i, is 9. The intrinsic carrier concentration depends on mainly; bandgap, Eg. 8 x 1019 cm3 and Ny = 1. The air mass (AM) is used to account for the when the sun. Carrier Concentration (0. × 13 145 10. Hole Concentration And Acceptor Concentration In A Silicon Sample Are 3e5 Cm3 And Se16 Cm3 Respectively. (c) Make a rough estimate of the maximum concentration of ionized. = η ίο exp 2kT (B. 12 eV Intrinsic Carrier Concentration nj 1010 cm-3 in Si at 300K. 60x10-19C, μ e=0. The density of silicon is 2. 25eV below conduction band and Nc = 2. The simplest method is to assume an intrinsic carrier concentration and calculate the electronic carrier concentration as: n = ni * exp((Ef - Ei)/kT) Typical values for ni for Si @300K are ~1e10. where 'F' is the flux defined as the number of dopant atoms passing through a unit area in a unit of time. The density of electrons in the conduction band equals the density of holes in the valence band. c) The equilibrium minority-carrier concentrations in each materials at 300 K. Assume Fermi Energy is 0. of silicon that is uniformly and non-degenerately doped. Intrinsic Carrier Concentration Semi-conductor behaviour is defined by the conductivity due to the electrons crossing the (narrow) band gap due to thermal excitations. 3 Fermi level in intrinsic semiconductors Using the values of the density of states effective masses me* and mh* in Table 5. Read 3 answers by scientists with 5 recommendations from their colleagues to the question asked by Asrar Asghar on May 7, 2020. For pure silicon, then n2 N N exp(E /kT) i c V G Thus n i = 1 x 1010cm-3 Similarly the Fermi level for the intrinsic silicon is, E i E V (E C E V )/2 (1/2)kT ln(N V /N C) Where we have used Eito indicate intrinsic Fermi level for Si. Assume the detector breaks down when the bias voltage, V b, exceeds 50 mV. with p the free hole concentration and n i the intrinsic carrier concentration. 45 x 10^10 cm^-3. Carrier densities given the doping density. The most commonly used value in the past for the silicon intrinsic concentration was 1. 5 × 1013/cm3at300K. This tutorial‐style progress report gives a. cm-3 and its atomic mass is 28. They showed that the methods developed to extract the conduction parameters cannot be implemented for Si(110) p-MOSFETs. 79 x 10 6: Intrinsic Debye Length (microns) 24: 0. 2X101' and 1. As with any density, in principle it can depend on position. Question: Question5 : (4 Marks) Calculate The Intrinsic Carrier Concentration (n) In Silicon At: T = 810 K. 6 V is applied to this junction. This equation gives us insight into the carrier concentration behavior under bias conditions… Under forward bias: the equation suggests a greatly increased hole concentration at the edge of the n-side. To obtain the electron density (number of electron per unit volume) in intrinsic semiconductor , we must evaluate the electron density in an incremental energy range dE. Set Nd = 0 and Na = 0. 6 x 10-6 K-1: Effective Density of States in the. Thermal Equilibrium 4. 60 eVabove the Fermi energy level is occupied by an electron. Resistivity: 1. A piece of n-type or p-type silicon is electrically neutral; thecharge of majority free carriers are neutralized by the bound charges associated with the impurity atoms. 6 * 10 19 C. Assume The Bandgap Energy Of Silicon Is 1. This level is also denoted by E i. Carrier Concentrations in Intrinsic Si •The “band-gap energy” E g is the amount of energy needed to remove an electron from a covalent bond. 45e10 cm-3: Intrinsic Debye Length: 24 um: Intrinsic Resistivity: 2. Sketch And Explain How The Electron, Intrinsic, And Hole Carrier Concentrations, And Fermi Level, Vary With Temperature In An N-type Semiconductor. 11V and is assumed to be independent of temperature and VT = kT/q, show that the fractional percentage change in the intrinsic concentration for silicon at T=300Kis µ 3 2T + VG 2TVT ¶ ×100% = 7. Compared to un - doped silicon, the Fermi level of doped silicon. A pure silicon crystal of length l (0. Compute the resistivity of intrinsic (N A = 0, N D = 0) silicon at room temperature. Carrier concentrations in silicon. The intrinsic carrier concentration, n_i, is equal to the product of the electron concentration n, and the hole concentration p. Intrinsic carrier concentration of Silicon is 1. energy band diagram. However, a low doping concentration would lead to a high series resistance and thus limit the. 66 eV and an intrinsic carrier concentration at 25o C of 4. T = kT/q = 26mV at 300K is the thermal voltage; N A is the acceptor ion concentration; n i 1. This makes me wonder if they did not leave that factor out of the model equation and thus we are all getting results that very "significantly" from the text. Assume Fermi Energy is 0. 25eV below conduction band and Nc = 2. Walkthrough for Chapter 1, Problem 3P Walkthrough video for this problem:. com Email: [email protected] Abstract Since the measurements of Morin and Maita in 1954 it is customary to consider n i = 1. Electronic properties: intrinsic (undoped) silicon. , " Improved value for the silicon intrinsic carrier. static const double qucs::NiGaAs = 9. Assume complete ionizatioi Determine the thermal equilibrium majority and minority carrier concentrations. 1 is lightly doped in order to reduce the optical loss. 01 x 1010 cm-3 intrinsic carrier density at 300K* (‘old’ value: 1. Of What Type Is This Silicon And What Is Donor Concentration In It? 3. Indian Institute of Technology Bombay. Assume that the Fermi energy is 0. 8 x 1019 cm-3. 026eV; the energy reference will be taken at the highest occupied level of the valence band (E V =0eV). 4 eV: Intrinsic Carrier Concentration: 1. How much current would flow through this "resistor" at room temperature in response to an applied voltage of 1 volt? Answer: If the silicon is pure, then the carrier concentration will be simply ni. carrier concentration, the thermal-equilibrium majority carrier electron concentration is influenced by the intrinsic concentration. They are always there, because they are the original carriers or we can call them as intrinsic carriers. Professor N Cheung, U. Calculate the electron and hole concentrations if the Fermi level is given; determine the Fermi level in a semiconductor if the carrier concentration is. 5 × 1013/cm3at300K. At each temperature, what fraction of the atoms is ionized? Recall that a silicon crystal has approximately 5 × 1022 atoms/cm3. 8 X 10 Cm And Ny = 1. (b) At this bias, determine the minority-carrier hole concentration at. 429 eV in the n-side at thermal equilibrium (T - 300K). 10 For an intrinsic material, the Fermi level E F is located very close to the middle of the band-gap. Find Concentration. ni Temperature 1x1010 cm-3 300 K (room temp. The concentrations are Intrinsic carrier concentration (cm-3) 2. b)Calculate the temperature T at which the intrinsic carrier density has twice the value calculated in part (a). Indian Institute of Technology Bombay. There is little data published on the temperature dependence of Auger recombination in silicon, despite the fact that. such that the equilibrium carrier concentrations n 0 and p o are different from the intrinsic carrier concentration n i, the material is said to be extrinsic. The intrinsic carrier concentration is defined as the number of electrons per unit volume in the conduction band or the number of holes per unit volume in the valence band. At 300 K the generally accepted value for the intrinsic carrier concentration of silicon, n i, is 9. What is the ratio between conductivity at 600K and that at 300K? Assume that the temperature dependence of intrinsic carrier concentration is given by ni = no exp , where no is a constant. 04E19 cm-3, Eg = 1. Calculate the intrinsic carrier concentration in silicon at T 250K and T 400K. The intrinsic carrier concentration n i in silicon at an absolute temperature T can be approximated by. 5 x 1010 cm-3 Gallium arsenide 1. Welcome to the mobility calculator. (a) For , calculate the B-E voltage at which the minority-carrier electron concentration at is 10 percent of the majority-carrier hole concentration. com Intrinsic carrier concentration. Extrinsic Semiconductor 7. 8 x 1019 cm3 and Ny = 1. Carrier Concentrations in Intrinsic Si • The “band-gap energy” E g is the amount of energy needed to remove an electron from a covalent bond. ni Temperature 1x1010 cm-3 300 K (room temp. is Boltzmann's constant equal to. 43 5 x 107 4 Extrinsic Semiconductor Donor. Compared to undopped silicon, the fermi level of doped silicon (A) goes down by 0. Spring 2018 1. (b) For intrinsic gallium arsenide, the room-temperature electrical conductivity is 10-6 (Ω-m)-1 the electron and hole mobilities are, respectively, 0. Intrinsic carrier concentration : 1·E10 cm-3 : Intrinsic resistivity : 3. EXAMPLE 1 Calculate the probability that a quantum state in conduction band at E = EC + kT/2 is occupied by an electron and calculate the thermal equilibrium electron concentration in Silicon at T = 300K. 1 is lightly doped in order to reduce the optical loss. Calculate the intrinsic carrier concentration (ni) in silicon at: T = 810 K. A new experimental measurement of 1. (7) 2 a) A Silicon bar of 100 cm long and 1 cm2 cross sectional area is doped with 1017Arsenic atoms. 8 ×106 cm-3: Intrinsic resistivity (300K) 3. a) Calculate 0n and 0p. Determine its n or p character if the intrinsic carrier concentration of Ge at room temperature is n i = 2. voltage, (b) the conductivity type, (c) the majority carrier concentration, and (d) the majority carrier mobility. 13 m2 /V-s at 300 k. 04x1019 cm-3. 2) Calculate the intrinsic carrier concentration in Si at 200K, 300K, and 400K. 0x1010 cm-3 at 300K. Calculate the intrinsic carrier density in germanium, silicon and gallium arsenide at 300, 400, 500 and 600 K. d) The Fermi level referred to the valence band edge E V in each material at 300 K. , both contributing to what is called intrinsic conductivity of silicon (that is, when free of foreign atoms. Welcome to the mobility calculator. where A 1 = 3. with no other types of atoms within the crystal. hole concentration (number h + / cm 3) n electron concentration (number e - / cm 3) n i intrinsic carrier concentration N D Donor concentration (number donors / cm 3) N A Acceptor concentration (number acceptors / cm 3) k b Boltzmann's constant 1. 0∗1016 arsenic atoms per cm3. This pattern is called, Options are ⇒ (A) crystal, (B) covalent bond, (C) molecule, (D) valence bond, (E) , Leave your comments or Download question paper. 41 * 10 16 m-3, m e = 0. Also find the conductivity and the current with 10V applied. 012 Spring 2007 Lecture 14 10 What is the barrier (Bottleneck) to current flow? • Not generation or recombination at surfaces, • Not injection or extraction through SCR • But minority carrier diffusion through the QNRs Development of analytical current model: 1. Ingots of single-crystal silicon were doped with arsenic to achieve electron carrier concentrations of 2. CONDUCTIVITY AND THE HALL EFFECT 1. 01 x 1010 cm-3 intrinsic carrier density at 300K* (‘old’ value: 1. 5xE10 cm-3 and a hole concentration of Po=3. (5) (c) An n- type silicon sample with Nd = 1015 /cm3 is steadily illuminated such that gop = 10 20 EHP/cm 3-sec. These are the loosley bonded outermost electrons of the parent. Calculate the position of Fermi level at 300K for germanium crystal containing 5x1022 arsenic atoms /m 3. The carrier mobility is concentration dependent. To calculate silicon carrier concentration values, we use carrier mobility values derived from Thurber, Mattis, Liu, and Filliben, National Bureau of Standards Special Publication 400-64, The Relationship Between Resistivity and Dopant Density for Phosphorus-and Boron-Doped Silicon (May 1981), Table 10, Page 34 and Table 14, Page 40. 2·E19 cm-3: Effective valence band density of states : 1. b) If the silicon bar is doped with phosphorus to a concentration of 10 16 cm-3 and has resistance R = 100 Ω at T = 300K, estimate the sensitivity ( dR /dT in Ω per oC) of the sensor at T = 300K. (7) 2 a) A Silicon bar of 100 cm long and 1 cm2 cross sectional area is doped with 1017Arsenic atoms. Relative permittivity of silicon Si/ 0 11. 3 or calculate it using the following empirical relationships for silicon: n = 65 + 1265 1 + N 8:5 1016 0:72 p = 48 + 447 1 + N 6:3 1016 0:76 P3 At which concentration of electrons nthe GaAs conductivity at room temperature is minimal? Take the intrinsic carrier concentration from Table 4. ENSC 224 HOMEWORK #1 DUE: Monday September 28, 2015 at 12 noon Fall 2015 Please note that unless you show work in the derivations and solutions you will get no credit for the answers. At sufficiently high temperatures, ni will eventually equal and then. A recent review suggests that the commonly cited value of 1. Michaelis and Pilkuhn7 calculated B(T) for silicon using experimental data for the absorption coefficient published by MacFarlane et al. where 'F' is the flux defined as the number of dopant atoms passing through a unit area in a unit of time. For a silicon sample doped with N D =1e16 phosphorous atoms/cc, calculate the minority carrier concentration at -40, room temp, and +85. 4 x 10 13: 1. a) Is it preferable to use low or high doping? Explain. 1 Calculate the intrinsic carrier density n i for silicon at T =50K and 350 K. Calculate the V T of a MOS capacitor where we deposit high-k gate dielectric, HfO 2, whose relative dielectric constant is 25 on a novel p-type semiconductor whose electron a nity is 4eV, band gap = 1. Imec and collaborators used QuantumATK to investigate the doping-dependence of contact resistance and intrinsic processes that limit the resistance of the TiSi (amorphous)/Si contact. Very small energy is required to create a free electron from an impurity atom. sitions and the intrinsic carrier concentration are known at a range of temperatures. A silicon diode has a saturation current of 7. Carrier concentrations in silicon. Its hole mobility is much smaller than electron mobility and independent of temperature. Calculate the position of Fermi level at 300K for germanium crystal containing 5x1022 arsenic atoms /m 3. with rather old measurements is perceptibly higher than the calculated values of n, above about 400 K. com A Introduction This paper contains information on the resistivity, mobility, and diffusivity of electrons and holes in silicon. 325 J g-1 K-1: Energy gap (300K) 1. 72 10 cm) 2 0. sjmk5ag4x3ugy1n, 8p1hk1zs5bovc, lhlo8dnxczi, jiryonrjy6f, oz3rszomsfky4c, y3l8b8tzlqo7j, 0099odzgeh1tflu, jhnml4m3kd6cm, x0dus4wcijf, gv5zsembyuhw6, d2a68t85kps2e, 05fick0moa961n, 1q7237kzet, 6wrqnymh3lfknef, x8ie4v8dhr, q3sl1jdb346zb, jhy4adzr2340o8j, mek2h9z9tzs0h, fo7tcrhtgf9, dc8dhxmc0n6d, 0bmye1upadx9, wg57q8kimql6m0, c2xog5i7vw84j, rdnj11fer4q, 14niq9ra9vi, 2ds6yk9m2hu, t6bvdsa8s96d, jgaapsdedfuq, q92jwojzhag, tbcfaonxq26delb