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Understanding the thermal stability and degradation mechanism of β-Ga2O3 metal-oxide-semiconductor field-effect transistors (MOSFETs) is crucial for their high-power electronics applications. This work examines the high temperature performance of the junctionless lateral β-Ga2O3 FinFET grown on a native β-Ga2O3 substrate, fabricated by metal-assisted chemical etching with Al2O3 gate oxide and Ti/Au gate metal. The thermal exposure effect on threshold voltage (Vth), subthreshold swing (SS), hysteresis, and specific on-resistance (Ron,sp), as a function of temperature up to 298 °C, is measured and analyzed. SS and Ron,sp increased with increasing temperatures, similar to the planar MOSFETs, while a more severe negative shift of Vth was observed for the high aspect-ratio FinFETs here. Despite employing a much thicker epilayer (∼2 μm) for the channel, the high temperature performance of Ion/Ioff ratios and SS of the FinFET in this work remains comparable to that of the planar β-Ga2O3 MOSFETs reported using epilayers ∼10–30× thinner. This work paves the way for further investigation into the stability and promise of β-Ga2O3 FinFETs compared to their planar counterparts.
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Thin channel Ga2O3 MOSFET with 55 GHz fMAX and > 100 V breakdown
This Letter reports a highly scaled 90 nm gate length β-Ga2O3 (Ga2O3) T-gate MOSFET with a power gain cutoff frequency (fMAX) of 55 GHz. The 60 nm thin epitaxial Ga2O3 channel layer was grown by molecular beam epitaxy, while the highly doped (n++) source/drain regions were regrown using metal organic chemical vapor deposition. Maximum on current (IDS,MAX) of 160 mA/mm and trans-conductance (gm) around 36 mS/mm were measured at VDS = 10 V for LSD = 1.5 μm device. Transconductance and on current are limited by high channel sheet resistance (Rsheet). Gate/drain breakdown voltage of 125 V was measured for LGD = 1.2 μm. We extracted 27 GHz current gain cutoff frequency (fT) and 55 GHz fMAX for 20 V drain bias for unpassivated devices. While no current collapse was seen initially for both drain and gate lag measurements for 500 ns pulse, moderate current collapse was observed after DC, RF measurements caused by electrical stressing. We calculated a high fT. VBR product of 3.375 THz V, which is comparable to the state-of-the-art GaN HEMTs. This figure of merit suggests that Ga2O3 could be a potential candidate for X-band application.
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- PAR ID:
- 10545893
- Publisher / Repository:
- Applied Physics Letters
- Date Published:
- Journal Name:
- Applied Physics Letters
- Volume:
- 125
- Issue:
- 6
- ISSN:
- 0003-6951
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.1063/5.0208580
