The electron and hole concentrations, n and p respectively obey the relation np = n²_i where n_i is the intrinsic carrier density. This expression is valid for which of the following?

A. Metals B. Semiconductors C. Insulators D. All of the above

A. Drift of holes B. Diffusion of holes C. Drift of electrons D. Diffusion of electrons

A. Both A and R are true and R is correct explanation of A B. Both A and R are true but R is not a correct explanation of A C. A is true but R is false D. A is false but R is true

A. Forward bias voltage B. Potential barrier C. Rate of thermal generation of electron hole pairs D. None of the above