Suppression of Drain Current Leakage and Short-Channel Effect in Lateral Ga2O3 RF MOSFETs Using (AlxGa1-x)2O3 Back-Barrier

• Published in: IEEE electron device letters 2023-11, Vol.44 (11), p.1829-1832
• Main Authors: Ohtsuki, Takumi, Kamimura, Takafumi, Higashiwaki, Masataka
• Format: Article
• Language: English
• Subjects: Back-barrier; Current leakage; drain current leakage; Electrodes; Equivalent circuits; Gallium oxides; Ga₂O₃ MOSFET; Ions; Logic gates; MOSFET; MOSFETs; Radio frequency; RF device; Silicon; Substrates; Transconductance
• ISSN: 0741-3106; 1558-0563
• DOI: 10.1109/LED.2023.3318215

An (AlxGa1-x)2O3 back-barrier was inserted into lateral Ga2O3 RF MOSFETs to suppress both the drain current ( {I}_{\text {d}} ) leakage through an epilayer/substrate interface and the short-channel effect. The {I}_{\text {d}} leakage was suppressed to a sufficiently low value of less than 1 nA/mm. As for the small-signal RF characteristics, a peak current gain cutoff frequency ( {f}_{\text {T}} ) of 10 GHz and a peak maximum oscillation frequency ( {f}_{\text {max}} ) of 24 GHz were obtained with gate length of 120-150 nm. Compared to our previous work without a back-barrier, a peak {f}_{\text {max}} appeared at the shorter gate length by 50-80 nm. Therefore, the insertion of an (AlxGa1-x)2O3 back-barrier was effective to suppress the {I}_{\text {d}} leakage and to a certain extent the short-channel effect. Delay-time analysis using a simplified small-signal equivalent circuit model indicates that increasing the AC transconductance and decreasing the extrinsic delay are the keys to achieve higher {f}_{\text {T}} .