Improved AlGaN/GaN Metal–Oxide– Semiconductor High-Electron Mobility Transistors With TiO2Gate Dielectric Annealed in Nitrogen

An AlGaN/GaN metal-oxide-semiconductor high-electron mobility transistor (MOS-HEMT) that uses a high-k TiO ₂ gate insulator is demonstrated. TiO ₂ films are annealed at 300 °C and 600 °C in N ₂ or O ₂ following the deposition of an oxide layer. Experimental results reveal that the 300 °C N ₂ -annealed TiO ₂ /GaN MOS capacitor has the smallest interface traps of any of the studied devices. The 300 °C N ₂ -annealed oxide interlayers between the GaN and the gate metal reduce the gate leakage current and improve the dc, high-frequency, and noise characteristics. The gate leakage current of the 300 °C N ₂ -annealed MOS-HEMT is more than 3 orders of magnitude less than that of the baseline HEMT. This brief is the first to fabricate a GaN-based MOS-HEMT using an N ₂ -annealed TiO ₂ gate insulator.