The band gap of Silicon at room temperature is:

The impurity commonly used for realizing the base region of a silicon n-p-n transistor is

n-type silicon is obtained by doping silicon with

The intrinsic carrier concentration of silicon sample at 300^oK is $$1.5\times10^{16}/m^3$$. If after doping, the number of majority carriers is $$5\times10^{20}/m^3$$ , minority carrier density is