Microscopic origin ofn-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$${}_{\mathrm{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.