Fabrication of relaxed InGaN pseudo-substrates composed of micron-sized pattern arrays with high fill factors using porous GaN

Abstract

Fully or partially relaxed micron-sized InGaN patterns with fill factors up to 69% were demonstrated via porosification of the underlying GaN:Si layer. The impact of the porosification etch conditions and the pattern geometry on the degree of InGaN relaxation were studied and monitored via high resolution x-ray diffraction reciprocal space maps. Additionally, a 45 nm redshift in the photoluminescence emission from InxGa1−xN/ InyGa1−yN multi-quantum wells (MQWs) regrown on bi-axially relaxed InGaN buffer layers was observed when compared to a co-loaded reference sample grown on GaN. The longer emission wavelength was associated with higher indium incorporation into the InGaN layers deposited on the InGaN base layers with a lattice constant larger than GaN, due to the reduced lattice mismatch between MQW and InGaN base layer, also called compositional pulling effect.