O₂ Plasma Alternately Treated ALD-Al₂O₃ as Gate Dielectric for High Performance AlGaN/GaN MIS-HEMTs

This article systematically studies the AlGaN/GaN MIS-HEMTs using the O ₂ plasma alternately treated Al ₂ O ₃ as gate dielectric. The X-ray photoelectron spectroscopy (XPS) analyses and capacitance-voltage (C-V) measurement results show that the density of the border traps originating from the Al-OH bonds in the ALD-Al ₂ O ₃ gate dielectric can be significantly reduced after the O ₂ plasma alternating treatment. Consequently, a low gate leakage current and a high field-effect mobility of 1680cm ² /V·s are achieved. The results also demonstrate that the fabricated AlGaN/GaN MIS-HEMTs with the O ₂ plasma alternating treatment exhibit improved performances, having a high ON/OFF ratio of ~1011, a steep subthreshold slope of 74 mV/dec, a small hysteresis (Δ V _TH ) of 0.1 V and small ON-resistance ( R _ON ) of 6.0 Ω·mm. The device thermal stability was also improved within the tested temperature range. In addition, the pulsed I _D - V _DS measurements with quiescent drain bias ( V _DS0 ) stress of 40 V present negligible current collapse (2%) and low degradation of dynamic R _ON by 1.04 times the static R _ON .