Structural and optical properties of Ga auto-incorporated InAlN epilayers

InAlN epilayers deposited on thick GaN buffer layers grown by metalorganic chemical vapour deposition (MOCVD) revealed an auto-incorporation of Ga when analysed by wavelength dispersive x-ray (WDX) spectroscopy and Rutherford backscattering spectrometry (RBS). Samples were grown under similar conditions with the change in reactor flow rate resulting in varying Ga contents of 12–24%. The increase in flow rate from 8000 to 24000sccm suppressed the Ga auto-incorporation which suggests that the likely cause is from residual Ga left behind from previous growth runs. The luminescence properties of the resultant InAlGaN layers were investigated using cathodoluminescence (CL) measurements. •We characterise Ga auto-incorporated InAlN epilayers grown by MOCVD.•WDX and RBS confirm presence of Ga within the layer.•Change in reactor flow rate resulted in Ga contents of 12–24%.•Increase in flow rate from 8000 to 24000sccm suppressed Ga auto-incorporation.•We report a broad InAlGaN luminescence whose peak energy varies with InN content.