Infrared luminescence of residual iron deep level acceptors in gallium nitride (GaN) epitaxial layers

Abstract

A characteristic infrared luminescence band, dominated by a zero-phonon line at 1.30 eV has been consistently detected in gallium nitride (GaN) epitaxial layers. It is assigned to the intra-3d-shell transitions 4T1(G)→6A1(S) of omnipresent iron trace impurities, Fe3+Ga(3d5). Another infrared emission is often also observed at 1.19 eV. This is tentatively assigned to chromium trace impurities, Cr4+Ga(3d2). The role of iron and chromium as minority-carrier lifetime killers in GaN-based optoelectronic devices is suggested from these data.