Figure 1
Schematic cross-sectional structure of the (a) p-GaN gate HEMT with ohmic gate contact and (b) the MOS-HEMT.
Figure 2
Cross-sectional TEM image of an over-etched substrate (containing oxidized [white]) and residual [light gray] AlGaN) by selective etching between p-GaN and AlGaN (top) and element distribution in the over-etched substrate generated from the EDS line scan (bottom).
Figure 3
TLM results of (a) the p-GaN gate HEMT with ohmic gate contact and the MOS-HEMTs (b) before and (c) after PDA treatment.
Figure 4
(a) Transfer characteristics of the HEMT with ohmic gate contact in linear scale: the left Y-axis shows the drain current, and the right Y-axis shows the transconductance. (b) Transfer characteristics in logarithmic scale: the left Y-axis shows the drain current, and the right Y-axis shows the gate leakage current. (c) Output characteristics of the device under different gate voltages.
Figure 5
(a) Comparison of transfer characteristics among the three types of HEMTs in a log scale and (b) in a linear scale.
Table 1
Comparison of typical performance parameters among the three types of HEMTs.
| Parameters | Ohmic gate | MOS-HEMT (w/o PDA) | MOS-HEMT (w/PDA) |
|---|---|---|---|
| V th (V) | 0.81 | 1.15 | 1.05 |
| SS (mV/dec) | 75.61 | 89.79 | 71.26 |
| g m,max (mS/mm) | 76.64 | 40.33 | 18.33 |
| Field effect mobility (cm2/V s) | 684 | 153 | 71.4 |
| I ON /I OFF | 2.17 × 1011 | 2.48 × 108 | 5.64 × 109 |
Figure 6
Comparison of I G–V G characteristics among the three types of HEMTs.
Figure 7
TDGB of MOS-HEMTs without (a) and with (d) PDA, Weibull plots of MOS-HEMTs without (b) and with (e) PDA, and lifetime predictions of MOS-HEMTs without (c) and with (f) PDA.