Determination of the GaN/AlN band offset via the (-/0) acceptor level of iron

Abstract

A characteristic infrared luminescence spectrum, dominated by a zero-phonon line at 1.30 eV, has been observed on AlN polycrystalline material. It is assigned to the spin-forbidden internal 3d–3d transition 4T1(G)→6A1(S) of Fe3+Al(3d5). By photoluminescence excitation spectroscopy the (-/0) acceptor level of iron in AlN could be located at EV+3.0 eV. The corresponding value for iron in GaN is EV+2.5 eV. From these values, the valence-band offset in AlN/GaN heterojunctions is predicted as ΔEV=0.5 eV, the conduction-band offset as ΔEC=2.3 eV.