Structural and optical properties of pseudomorphic InxGa1−xN alloys

Thick (225 nm) InxGa1−xN layers, grown on 5 μm thick GaN, were found by x-ray diffraction (XRD) measurements to be pseudomorphic up to x=0.114. Transmission electron microscopy showed that no misfit or additional threading dislocations were created at the InxGa1−xN/GaN interface. Composition of the overlayers was determined by Rutherford backscattering spectrometry and correlated to both the a and c lattice constants from XRD. It was found that Vegard’s law is applicable at these compositions, if the biaxial strain is included. Biaxial strain must also be considered to accurately determine the bowing parameter as shown by optical transmission measurements.