Effects of Si-doped GaN insert layer in AlGaN/GaN/GaN:Si/AlN DH-HEMT structure

In this study, we investigate the effects of Si-doped GaN insert layer on the structural and electrical characteristics of AlGaN/GaN/GaN:Si/AlN double-heterostructure high-electron-mobility transistor (DH-HEMT). Compared with an AlGaN/GaN/AlN HEMT without a Si-doped GaN layer, the AlGaN/GaN/GaN:Si/AlN DH-HEMT showed an improved root-mean-square roughness of 0.57 nm and a decreased GaN channel compressive stress of -1.44 GPa. Also, an increased two-dimensional electron gas mobility of 1845 cm(2)/V.s and a reduced specific contact resistance of 1.49 x 10(-6) Omega.cm(2) were obtained. The direct-current output results showed an increased maximum drain current of 600 mA/mm and transconductance of 130 mS/mm, which was attributed to the enhanced 2DEG mobility and reduced contact resistance by the insertion of Si-doped GaN layer in the DH-HEMT.