p -type conductivity in cubic (Ga,Mn)N thin films

Abstract

The electrical properties of p-type cubic (Ga,Mn)N films are reported. Hole concentrations above 1018cm−3 at room temperature are observed. Activated behavior is observed down to 150 K, with an acceptor ionization energy of around 45–60 meV. The dependence of hole concentration and ionization energy on Mn concentration indicates that the shallow acceptor level is not simply due to unintentional codoping. Thermopower measurements on freestanding films, capacitance–voltage profilometry, and the dependence of conductivity on thickness and growth temperature, all show that this is not due to diffusion into the substrate. We therefore associate the p-type conductivity with the presence of the Mn in the cubic GaN films.