Growth and photoluminescence studies of Zn-doped AlN epilayers

Abstract

Deep ultraviolet time-resolved photoluminescence (PL) spectroscopy has been employed to study Zn-doped AlN epilayers grown by metal-organic chemical vapor deposition. The PL spectra of Zn-doped AlN epilayer exhibited two impurity emission lines at 5.40 and $4.50\mathrm{eV}$ , which were absent in undoped epilayers and assigned to the transitions of free electrons and electrons bound to nitrogen vacancies with three positive charges ($0.90\mathrm{eV}$ deep) to the ${\mathrm{Zn}}^0$ acceptors. By comparing PL spectra of Zn- and Mg-doped AlN epilayers with undoped epilayers, it was deduced that Zn energy level is about $0.74\mathrm{eV}$ , which is about $0.23\mathrm{eV}$ deeper than the Mg energy level $\left(0.51\mathrm{eV}\right)$ in AlN. It is thus concluded that contrary to theoretical prediction, Zn would not be a better candidate than Mg as an acceptor dopant in AlN.