(a) rho = 2 ohm-cm
N_A=2.31e+015 /cm^3
N_D=1.64e+015 /cm^3
The height of the potential energy barrier is:
V_0=0.227 eV

(b)For silicon:
N_A=8.33e+015 /cm^3
N_D=2.40e+015 /cm^3
The height of the potential energy barrier is:
V_0=0.656 eV