Improved Interface and Transport Properties of AlGaN/GaN MIS-HEMTs With PEALD-Grown AlN Gate Dielectric

In this paper, we demonstrated AlGaN/GaN metal-insulator-semiconductor high-electron mobility transistors (MIS-HEMTs) with AlN gate dielectric grown by plasmaenhanced atomic layer deposition (PEALD). The high-quality interface of AlN/AlGaN/GaN MIS-HEMTs resulted in a very small threshold voltage (Vth) hysteresis and dispersion. Simultaneously, the MIS-HEMTs exhibited a high-peak transconductance of 289 mS/mm and a small Vth shift of 0.8 V, while those for Al₂O₃/AlGaN/GaN metal-oxide-semiconductor HEMTs were 203 mS/mm and 5.2 V, respectively. Furthermore, analysis indicated that PEALD-grown AlN significantly reduced the interface charges at dielectric/III-N interface (from 1.2 × 10¹³ to 8 × 10¹² cm^-2 eV^-1 for interface traps, and from 1.01 × 10¹³ to 3.1 × 10¹¹ cm^-2 for fixed charges) and improved channel transport properties (the full-width at half-maximum of channel transconductance increased from 0.9 to 2.7 V), compared with ALD-grown Al₂O₃, which could explain the differences of device characteristics.