Physics - Semiconductors Question with Solution | TestHub
The band diagrams of three semiconductors p, n and intrinsic are given in the figures (1), (2) and (3). C and V are the conduction and valence bands and is the Fermi level. Figures, from (2),(1) and (3) respectively represent the type of semiconductors as
Options:
Answer:
Solution:
In an intrinsic semiconductor, the number of electrons in the conduction band is equal to the number of holes in the valence band. Therefore, the Fermi level () lies exactly in the middle of the energy gap between the conduction band (C) and the valence band (V). This corresponds to figure (1).
In a p-type semiconductor, the concentration of holes in the valence band is much greater than the concentration of electrons in the conduction band. As a result, the Fermi level shifts downwards and lies close to the valence band. This corresponds to figure (2).
In an n-type semiconductor, the concentration of electrons in the conduction band is much greater than the concentration of holes in the valence band. Consequently, the Fermi level shifts upwards and lies close to the conduction band. This corresponds to figure (3).
The question asks for the types of semiconductors represented by figures (2), (1), and (3) respectively. Based on our analysis, the sequence is p-type, intrinsic, and n-type.
Answer: p, intrinsic and n
