Demonstration of vertically-ordered h-BN/AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors on Si substrate

Highlights: • GaN transistor with high thermal conductivity boron nitride dielectric film. • Vertically ordered hexagonal-BN by high-power impulse magnetron sputtering. • Enhanced transistor performance due to good interface between boron nitride and GaN. AlGaN/GaN metal–insulator-semiconductor high-electron-mobility transistors (MISHEMTs) have been demonstrated with 22 nm thick vertically ordered (VO) h-BN by high-power impulse magnetron sputtering deposited at room temperature for the first time. About two orders of magnitude lower gate leakage current was observed in VO h-BN/AlGaN/GaN MIS-diodes compared to conventional Schottky diodes. The fabricated MISHEMT and HEMT with 2 µm gate-length exhibited a maximum drain current density (I_Dmax) of 685 and 467 mA/mm and a maximum extrinsic transconductance (g_mmax) of 93 and 134 mS/mm, respectively. The VO h-BN/AlGaN/GaN MISHEMT with improved characteristics is due to an enhanced sheet carrier density (from 7.29 × 10¹² cm⁻² to 1.10 × 10¹³ cm⁻²) by surface passivation of VO h-BN as well as the good VO h-BN/GaN interface quality with a minimum interface state density of 2.6 × 10¹² cm^-2eV⁻¹.