Extrinsic and intrinsic nonradiative recombination channels in deep ultraviolet ( <i>λ</i>  &amp;lt; 230 nm) light emitting heterostructures made of group III element nitrides

Abstract

The optical performance of nitride-based heterostructures that spontaneously emit light in the deep-ultraviolet range (wavelengths below 230 nm) is limited by various previously elucidated phenomena related to the details of the valence band structure, the need to resolve various technological issues with a view to improving electrical injection, and the need to address light extraction issues. In this article, we compare the light–matter interaction strategy in high-quality multiple quantum wells developed by both molecular beam epitaxy and organometallic vapor phase epitaxy, using temperature-dependent photoluminescence measurements performed in the range 8–300 K. The deterioration of light emission between 8 and 300 K is governed by two recombination mechanisms operating at low temperatures (below approximately 100 K) and at higher temperatures, respectively. The efficiency of the non-radiative recombination channel at low temperatures is extrinsic in origin; it is mediated by impurities and by the density of defects in the crystal. The second process is intrinsic in nature and is related to the thermal ionization of excitons at higher temperatures. We believe that the ultimate solution to partially reduce these phenomena could be homoepitaxy on high-quality AlN substrates.