1. What is the equilibrium concentration of electrons and holes in an n-type silicon at T=21.2°C (ni = 1.0x1010cm-3) in which NDD=4x1010cm-3 and are all ionized, and NAA=0? How much error is introduced if the intrinsic electron is neglected?
2. A homogeneously doped n-type Si at 21.2°C (n1-=1.00x1010cm-3) has NDD= 1.25X1015cm-3 donors and NAA=0.25x1015cm-3 acceptors, all of which are ionized. At some instance of time, for example t=13:00, the carrier concentrations were found to be N=1.25x1015cm-3 and P=0.25x1015cm-3 and were uniform over the entire volume of the crystal.
(a) Is the crystal electrically neutral at P-13:00?
(b) Why is the crystal not at thermodynamic equilibrium at t=13:00 and back up your answer quantitatively?