複選題Problem 19Which of the following statements for a p-n diode are correct? (A) Under the unbiased condition, the Fermi levels in p and n regions are aligned. (B) When no voltage is applied, the thermal electron current and the recombination electron current have the same magnitude but flow in opposite directions, resulting in no net current. (C) Under reverse bias, the recombination current is less than the thermal electron current. (D) When a positive voltage is applied to the p-side, the conventional current flows in the same direction as the electron current. (E) The photon energy emitted by a light-emitting diode corresponds to the energy gap during the transition of carrier under forward bias.

Problem 6 Consider the transmission of an incident electron with energy E through the one dimensional step potential barrier V(x) with V(x ＜ 0) = 0 outside the barrier, and V(x ＞ 0) = Vo in the barrier (V0 ＞ 0). Which of the following statements is CORRECT about the transmission coefficient T? (A) If the incident electron comes from x = +infinity, with E＞ V0,then the corresponding T = 1. (B) If the incident electron comes from x = - infinity, with E ＞V0, then the corresponding T = 1. (C) If the incident electron comes from x = - infinity, with E＜V0, then it has a nonvanishing probability in the barrier as well as T ＞ 0 due to quantum tunneling. (D) Replace V(x) by a potential barrier of finite width, with V(0 ＜ x ＜W) = Vo in the barrier and V(x) = 0 outside the barrier. An incident electron with E＜V0 has T ＞ 0 due to quantum tunneling. (E) None of the above.

相關試題

相關試卷