level. What are the electron and hole concentrations? c. A Si wafer is doped \textit{n}-type with $N_D = 10^{16} \text{cm}^{-3}$. At $T \approx 0K$, what are the equilibrium electron and hole concentrations?
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(a). A silicon wafer is uniformly doped p-type with Na = 10^15 cm -3 . At T = 0K. What are the equilibrium hole and electron consentrations? (b). A semiconductor is doped with an impurity concentration N such that N>>ni and all the impurities are ionized. Also n-N and p = ni^2/N. Is the impurity a donor or acceptor? Explain (c). The electron concentration in peace of Si at T = 300K under equilibrium conditions is 10^5 cm-3. What is the hole concentration? (d). For a silicon sample at T = 300K, the Fermi level is located 0.259 eV above the intrinsic Fermi level. What are hole and electron concentrations?
Adriano C.
Problem 2: (a) A silicon wafer is uniformly doped p-type with NA = 10^17 cm^-3. At T = 0K, what are the equilibrium hole and electron concentration? (b) The electron concentration in a piece of Si maintained at 300 K under equilibrium conditions is 10^3 cm^-3. What is the hole concentration? (c) For a silicon sample maintained at T = 300 K, the Fermi level is located 0.3 eV above the intrinsic Fermi level. What are the hole and electron concentrations? (d) In a nondegenerate germanium sample maintained under equilibrium conditions near room temperature, it is known that ni = 10^13 cm^-3, 2n = p, and ND = 0. Determine n and NA.
Adi S.
1.16 A silicon sample is doped with Nd = 10^15 cm^-3 of As atoms. (a) What are the electron and hole concentrations and the Fermi level position (relative to Ec or Ev) at 300 K? (Assume full ionization of impurities.) (b) Check the full ionization assumption using the calculated Fermi level, (i.e., find the probability of donor states being occupied by electrons and therefore not ionized. Assume that the donor level lies 50 meV below the conduction band, i.e., Ec - ED = 50 meV.) (c) Repeat (a) and (b) for Nd = 10^18 cm^-3. (Discussion: when the doping concentration is high, donor (or acceptor) band is formed and that allows all dopant atoms to contribute to conduction such that "full ionization" is a good approximation after all). (d) Repeat (a) and (b) for Nd = 10^17 cm^-3 but T = 30 K. (This situation is called dopant freeze-out.)
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