Microscopic origin of n-type behavior in Si-doped AlN

Abstract

In contrast to a long held belief, it has been shown that n-type AlN can be achieved through Si-doping. This is unexplainable from the current theoretical understanding, a situation that hinders further progress in AlN-based ultraviolet (UV) technologies. From first-principles calculations, we find that n-type behavior arises under N-rich growth conditions due to high Si solubility and to the formation of V Al-bound Si clusters. We show that metal-rich growth may lead to weak n-type behavior due to oxygen impurities binding and deactivating cation vacancies. We provide clues for designing production processes for n-type AlN as a base material for potential new UV sources.