Question

1. Semiconductor and Metal-Semiconductor Interface: (a) Sketch the band diagram of a p-type doped GaAs substrate with a dopingconcentration of 1 x 1017 cm3. Calculate the position of Fermi level EF with respectto the intrinsic energy level E; assuming Boltzmann statistics. In the sketch, clearlyindicate the conduction and valence bands, the intrinsic energy level, the position ofthe Fermi level with respect to the intrinsic energy level, and the bandgap energywith its value in electronvolts. (b) How would the position of Fermi level EF with respect to the intrinsic energy level E; change, if instead of Boltzmann statistics, Fermi-Dirac statistics were used? (c) Sketch the band diagram of a metal-semiconductor interface for the contactwhich has a Schottky barrier at the interface assuming the semiconductor material isdoped n-type. (d) Also sketch the band diagram of a metal-semiconductor interface for the contactwhich is considered to be Ohmic (e) Write a comparison of the two contact interfaces and explain the differences observed in l-V characteristics obtained from measurements from these two types of metal contacts in no more than 100 words.

Fig: 1

Fig: 2

Fig: 3

Fig: 4

Fig: 5

Fig: 6