AlGaN/GaN/InGaN/GaN DH-HEMTs with GaN channel layer grown at high temperature Lu Zhang, Xiaoliang Wang, Hongling Xiao, Hong Chen, Chun Feng, Guangdi Shen, Zhanguo Wang and Xun Hou Eur. Phys. J. Appl. Phys., 62 2 (2013) 20105 Published online: 22 May 2013 DOI: 10.1051/epjap/2013120390