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 Al2O3 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-Al2O3 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 similar to 10(11), a steep subthreshold slope of 74 mV/dec, a small hysteresis (Delta V-TH) of 0.1 V and small ON-resistance (R-ON) of 6.0 Omega.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).