Characterization of ZnO structures by optical and X-ray methods

► Comparison of optical and X-ray results on GaInZnO samples with Ga < 1 at%. ► Elemental composition determined by reference-free X-ray fluorescence. ► Correlation of the Raman-active dopant mode from Ga at 580 cm−1 with the Ga concentration. ► Surface nanoroughness taken into account for determination of accurate optical properties. ► Both the peak amplitude and the gap energy of ϵ2 increase as a result of annealing and decrease with increasing Ga content.