Ultrathin Barrier Layer AlN/GaN HEMTs Grown by Molecular Beam Epitaxy

With the continuous development of GaN-based high electron mobility transistors (HEMTs) in the field of high frequency, the short channel effect of traditional AlGaN/GaN HEMTs is beginning to appear. The strongly polarized thin barrier AlN barrier materials can solve this problem well, but the epitaxy growth of AlN/GaN heterojunction with high lattice mass is very difficult. In this work, AlN/GaN heterojunction with surface roughness less than 1 nm was successfully grown by molecular beam epitaxy (MBE) equipment. The two-dimensional electron gas density of, mobility of about 832 and sheet resistance of about 386 were obtained by contact hall test. On this basis, an HEMT device with gate length was fabricated. The saturation current reached 832 mA/mm and the maximum transconductance peak was 235 mS/mm. It shows the great potential of AlN/GaN heterojunction in RF power field.