1. (a) For each of the following material types, sketch a flat band diagram and describe the electronic structure: (i) Intrinsic semiconductor. (ii) Extrinsic semiconductor. (iii) Metal. (iv) Insulator. (b) The free carrier density in an extrinsic semiconductor is given by: 3 - Egap nc = P = ATZe 2kBT For silicon A = 1021 m-K, Egap = 1.1 eV, H = 0.15 ms-V-, h = 0.06 msV-and k 10-23 JK-. = 1.38 x Calculate the difference in the expected conductivity of silicon at room temperature and at 200 C. (3 marks) (3 marks) (3 marks) (3 marks) (8 marks)

(a) For each of the following material types, sketch a flat band diagram and describe the electronic structure: (i) Intrinsic semiconductor. (3 marks) (ii) Extrinsic semiconductor. (3 marks) (iii) Metal. (3 marks) (iv) Insulator. (3 marks) (b) The free carrier density in an extrinsic semiconductor is given by: nc=pv=AT23e2kBTEgap For silicon A=1021m3K23,Egap=1.1eV, e=0.15m2s1V1,h=0.06m2s1V1andkB=1.381023JK Calculate the difference in the expected conductivity of silicon at room temperature and at 200C