Low gate interface traps AlGaN/GaN HEMTs using a lattice matched ZrZnO transparent gate design

AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors (MIS-HEMTs) using a radio-frequency magnetron sputtered ZrZnO transparent oxide layer as a gate insulator are investigated and compared with traditional GaN HEMTs. A negligible hysteresis voltage shift in the C-V curves is seen, from 0.09 V to 0.36 V, as the thickness of ZrZnO films increases. The composition of ZrZnO at different annealing temperatures is observed using X-ray photoelectron spectroscopy (XPS). The ZrZnO thin film achieves good thermal stability after 600 C, 700 C and 800 C post-deposition annealing (PDA) because of its high binding energy. Based on the interface trap density analysis, D_it has a value of 2.663 × 10¹² cm^-2/eV for 10-nm-thick ZrZnO-gate HEMTs and demonstrates better interlayer characteristics, which results in a better slopes for the I_ds degradation (5.75 × 10^-1 mA/mm K^-1) for operation from 77 K to 300 K. The 10-nm-thick ZrZnO-gate device also exhibits a flat and a stable 1/f noise, as V_GS-V_th, and at various operating temperatures. Therefore, ZrZnO has good potential for use as the transparent film for a gate insulator that improves the GaN-based FET threshold voltage and improves the number of surface defects at various operating temperatures.