4. Concentration questions with a twists

a) A silicon wafer is uniformly doped p-type with NA-10¹6/cm³. At T = OK, what

are the equilibrium hole and electron concentrations?

b) A semiconductor is doped with an impurity concentration N such that N >>n;

and all the impurities are ionized. Also, p= N and n = n²/N. Is the impurity a

donor or an acceptor? Explain.

c) The electron concentration in a piece of Si maintained at 300K under

equilibrium conditions is 10%/cm³. What is the hole concentration?