Dependence on composition of the optical polarization properties of m -plane In x Ga1− x N commensurately grown on ZnO

We have grown m-plane InxGa1−xN (x = 0.24-0.43) commensurately on m-plane ZnO by the use of a low temperature epitaxial growth technique and investigated its optical properties. We found that the critical thickness for strain relaxation in the InGaN films prepared by the present technique is at least one order of magnitude larger than those reported by the other techniques. Polarized optical absorption measurements revealed that the allowed optical transition between the conduction band and the topmost valence band in m-plane InxGa1−xN (x = 0.24−0.43) on ZnO is for light polarized along c-axis. We found that the valence band splitting energy strongly depends upon the In composition. The values of the deformation potentials of InN were determined as D3 = 2.4 eV, D4 = −6.3 eV, and D5 = −1.2 eV, by fitting the experimental results with theoretical calculations based on the k·p approach.