Question

anium and diamond all have the same cryst a) Silicon, germ al structure. Why are the first two semiconductors while diamond is an insulator? (b) The xenon flash tube used in this experiment produces a wide range of photorn energies (i) Which energy would you expect to produce most of the carrier pairs? (You should be able to use the information presented in your answer to (a) to answer this question (ii) To what frequency and wavelength does this energy correspond? (ii) In what part of the electromagnetic spectrum does this energy lie? (iv) Describe a simple experiment which would test the hypothesis in (i)

Answer 1

(a) From the band gap theory we can say that diamond has a very large band gap as compared to silicon or germanium, hence it is an insulator. The covalent bond formed in diamond structure is very strong hence the overlap between orbitals is more, this leads to a large band gap as compared to silicon and germanium where overlap is less. Due to less overlap, they act as semi conductors.