Theoretical study of In_xAl_1‐xN/ZnO and In_xGa_1‐xN/ZnO strained quantum well lasers

Abstract

We perform a theoretical study of InxAl1‐xN/ZnO and InxGa1‐xN/ZnO strained Quantum Well (QW) Lasers oriented along the non‐polar A‐plane axis. In order to determine the energy band‐offsets in both heterostructures as a function of alloy composition, we use the ab‐initio method to compute the total energies of these systems. Then, we use the k·P method within the envelop function formalism to study conduction and valence energy subband structures for various alloy compositions and well widths. Finally, we calculate the Laser gain for such strained QW heterostructures. Our results show that type I heterostructures can be made with two kind of systems: InxGa1‐xN/InxAl1‐xN/ZnO and InxGa1‐xN/InyGa1‐yN/ZnO where InxGa1‐xN is the QW in both cases. These heterostructures are lattice‐matched along A‐plane axis at x=32% in InxAl1‐xN/ZnO and x=17% in InxGa1‐xN/ZnO. However, because of the anisotropy of the built‐in strain at the interface, they are still slightly compressively strained along c‐axis. Pure tensile strain or pure compressive can be achieved only at In‐content values well below or well above these critical values, respectively. Our results are compared with various theoretical and experimental values, and quite good agreement is found. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)