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

Abstract

This article systematically studies the AlGaN/GaN MIS-HEMTs using the O2 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 O2 plasma alternating treatment. Consequently, a low gate leakage current and a high field-effect mobility of 1680cm2/ $\text{V}\cdot \text{s}$ are achieved. The results also demonstrate that the fabricated AlGaN/GaN MIS-HEMTs with the O2 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 ( $\Delta V_{\mathrm {TH}}$ ) of 0.1 V and small ON-resistance ( $R_{\mathrm {ON}}$ ) of $6.0~\Omega \cdot $ mm. The device thermal stability was also improved within the tested temperature range. In addition, the pulsed $I_{\mathrm {D}}$ - $V_{\mathrm {DS}}$ measurements with quiescent drain bias ( $V_{\mathrm {DS0}}$ ) stress of 40 V present negligible current collapse (2%) and low degradation of dynamic $R_{\mathrm {ON}}$ by 1.04 times the static ${R} _{\mathrm {ON}}$ .

Keywords

• AlGaN/GaN MIS-HEMTs
• border traps
• current collapse
• plasma alternately treated gate dielectric