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

Abstract
A characteristic infrared luminescencespectrum, dominated by a zero‐phonon line at 1.30 eV, has been observed on AlN polycrystallinematerial. It is assigned to the spin‐forbidden internal 3d–3d transition 4 T 1(G)→6 A 1(S) of Fe3+ Al(3d 5). By photoluminescence excitation spectroscopy the (‐/0) acceptor level of iron in AlN could be located at E V +3.0 eV. The corresponding value for iron in GaN is E V +2.5 eV. From these values, the valence‐band offset in AlN/GaN heterojunctions is predicted as ΔE V =0.5 eV, the conduction‐band offset as ΔE C =2.3 eV.