Anisotropic structural and optical properties of a-plane (11-20) AlInN nearly-lattice-matched to GaN
Abstract
We report epitaxial growth of a-plane (11-20) AlInN layers nearly-lattice-matched to GaN. Unlike for c-plane oriented epilayers, a-plane Al1-xInxN cannot be simultaneously lattice-matched to GaN in both in-plane directions. We study the influence of temperature on indium incorporation and obtain nearly-lattice-matched Al0.81In0.19N at a growth temperature of 760oC. We outline a procedure to check in-plane lattice mismatch using high resolution x-ray diffraction, and evaluate the strain and critical thickness. Polarization-resolved optical transmission measurements of the Al0.81In0.19N epilayer reveal a difference in bandgap of ~140 meV between (electric field) Eparallelc [0001]-axis and Eperpendicularc conditions with room-temperature photoluminescence peaked at 3.38 eV strongly polarized with Eparallelc, in good agreement with strain-dependent band-structure calculations.