Improvement of electrical properties of MOCVD grown Al_xGa _1-xN/GaN heterostructure with isoelectronic Al-doped channel

To improve electrical characteristics of AlGaN/GaN heterostructure for HFET application, high quality AlGaN/GaN was grown by metal organic chemical vapour deposition on sapphire. We applied the isoelectronic Al-doping into the GaN channel layers of both conventional AlGaN/GaN and modified AlGaN/AlN/GaN heterostuctures. 2DEG mobilities of 1690 and 9280 cm²/Vs were measured for 25 nm Al_0.3Ga_0.7N/1 nm AIN/70 nm Al-doped channel/GaN heterostucture at 300 and 77 K, respectively. The improved result can be explained by both a decrease in the compensating acceptor or other defects associated with the formation of screw dislocation through the Al incorporation in the channel layer and a decrease in alloy disorder scattering at heterostructure by introducing binary thin AlN layer between Al _0.3Ga_0.7N and Al-doped channel layer.