Effects of initial GaN growth mode on the material and electrical properties of AlGaN/GaN high-electron-mobility transistors

AlGaN/GaN high-electron-mobility transistors (HEMTs) with different initial GaN growth modes were prepared on AIN/sapphire substrates. Secondary ion mass spectroscopy and Hall effect measurements confirmed that a highly conductive n-type region was generated at the GaN/AIN buffer interface during the three-dimensional to two-dimensional (3D-2D) growth mode transition. This n-type region was created by oxygen impurity incorporation during the 3D-2D growth mode transition, and its thickness increased with the transition time. The existence of this n-type conduction path not only changed the material properties but also degraded the device performance of HEMTs. (C) 2014 The Japan Society of Applied Physics