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 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
${R} _{\mathrm {ON}}$
.