Question 1
Consider the figure below which shows the energy-band splitting of silicon. If the equilibrium lattice spacing were to change by a small amount, discuss how you would expect the electrical properties of silicon to change. Determine at what point the material would behave like an insulator or like a metal.
Question 2
In terms of electron energy band structure, discuss, using diagrams, reasons for the difference in electrical conductivity between metals, semiconductors, and insulators
Question 3
(a) Explain why no hole is generated by the electron excitation involving a donor impurity atom.
(b) Explain why no free electron is generated by the electron excitation involving an acceptor impurity atom.
Question 4
The following electrical characteristics have been determined for both intrinsic and p-type extrinsic indium phosphide (InP) at room temperature:
σ (Ω -m)-1 n (m-3) p (m-3)
Intrinsic 2.5 × 10-6 3.0 × 1013 3.0 × 1013
Extrinsic (n-type) 3.6 × 10-5 4.5 × 1014 2.0 × 1012
Calculate electron and hole mobilities.