Critical layer thickness determination of GaN/InGaN/GaN double heterostructures

We report on the critical layer thickness of GaN/InxGa1−xN/GaN double heterostructures in the composition range 0<x<0.16. The evolution of the photoluminescence spectra and the electrical properties of the InxGa1−xN well were monitored as its thickness was increased for a given % InN. Due to compressive stress and possible quantum-size effects, the emission energy from thin InGaN wells is blueshifted relative to thicker wells of a given % InN. The transition from the blueshifted emission of strained InGaN to redshifted emission of relaxed InGaN is also accompanied by dramatic changes in film conductivity and mobility. The thickness at which the onset of relaxation occurs is deemed the critical layer thickness of the InxGa1−xN film.