1. The electron concentration in the conduction band of a GaAs sample is 10^5/cm^3 at room temperature. Is it p type or n type, how do you know?
2. Based on the Kronig-Penny model, would you expect the bandgap of a semiconductor to increase, decrease, or stay the same as mecahnical pressure is applied and why?
3. Two n-type semiconductor samples are made with the same non-degenerate doping density but one is silicon and one is GaAs. Which sample will have lower resistivity and why?