Influence of excited states of Mg acceptors on hole concentration in GaN

摘要

The influence of the excited states of the acceptors on the hole concentration in p-type GaN is investigated theoretically and experimentally. Using the temperature dependence of the hole concentration p(T) in Mg-doped GaN epilayers, a distribution function suitable for Mg acceptors is examined. It is found that the influence of their excited states on p(T) as well as the temperature dependence of the average acceptor level cannot be ignored, when the acceptor level is deep ( ≥ 150 meV). Moreover, it is elucidated that due to their excited states the ionization efficiency of acceptors is higher at elevated temperatures than the ionization efficiency expected from the Fermi-Dirac distribution function.