Electron mobility in GaN layers and HEMT structure optimized by MOVPE technological parameters

•Influence of growth parameters on transport properties of GaN was systematically studied.•Optimal technology to achieve high electron mobilities was identified.•Optimal growth conditions were 950 °C, TEGa, low growth rate, nitrogen atmosphere, 150 mbar.•Improved channel technology increased electron mobility in the channel by 30 % to 1896 cm2/vs.•Necessity to check reliability of van der Pauw results by CV measurement is demonstrated.