AlGaN/GaN MISHEMTs on silicon using atomic layer deposited ZrO2 as gate dielectrics

Conventional Schottky-metal gate based GaN HEMTs (SB-HEMTs) suffer undesirable high gate leakage current (I gleak ) issue. To reduce the I gleak , varieties of gate insulators like Si 3 N 4 , SiO 2 , Al 2 O 3 , Ga 2 O 3 , HfO 2 , Sc 2 O 3 etc. have been demonstrated to obtain high quality metal-insulator-semiconductor (MIS) structure. ZrO 2 , with a high dielectric constant (18-25 [1]) and large bandgap (5.2-7.8 eV [2]), is a good candidate for gate insulation layer. Compared with ZrO 2 prepared by other techniques, atomic layer deposited (ALD) technique has the benefits of nanometer scalability, high uniformity, good coverage, low defect density, etc. S. Abermann et al. [3] and A. Alexewicz et al. [4] have reported InAlN/GaN MISHEMTs using ALD ZrO 2 . However to-date, comprehensive study was not carried out in AlGaN/GaN MISHEMTs on Si with ALD ZrO 2 as insulator layer. In this paper, we demonstrated AlGaN/GaN MISHEMTs with ALD ZrO 2 as the gate dielectric layer on Si substrate. The use of ALD ZrO 2 dielectrics can effectively suppress the reverse gate leakage current and improve gate voltage up to +5 V.