Abstract: We study the growth of an InGaN and AlGaN/GaN/InGaN/GaN double heterojunction structure by metal organic chemical vapor deposition (MOCVD). It is found that the crystal quality of the InGaN back barrier layer significantly affects the electronic property of the AlGaN/GaN/InGaN/GaN double heterojunction. A high crystal quality InGaN layer is obtained by optimizing the growth pressure and temperature. Due to the InGaN layer polarization field opposite to that in the AlGaN layer, an additional potential barrier is formed between the GaN and the InGaN layer, which enhances carrier confinement of the 2DEG and reduces the buffer leakage current of devices. The double heterojunction high-electron-mobility transistors with an InGaN back barrier yield a drain induced barrier lowering of 1.5 mV/V and the off-sate source-drain leakage current is as low as 2.6 μA/mm at V_DS = 10 V.

Key words: InGaN back barrier, double hererojunction, carrier confinement