Enhancement of ionization efficiency of acceptors by their excited states in heavily doped wide bandgap semiconductors

In this article, a distribution function suitable for acceptors in heavily doped p-type SiC and GaN is investigated using p(T) obtained by Hall-effect measurements. Since the Fermi levels in heavily doped samples are located between the valence band and the acceptor level, which indicates that the Fermi level is close to the excited state levels, there are a lot of holes at the excited states of acceptors. This suggests that a distribution function for acceptors should include the influence of the excited states of acceptors. Therefore, we here consider two distribution functions; (1) the Fermi-Dirac distribution function / FD (AEa ) not including it and (2) our proposed distribution function / (AEA) including it [1-4].