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Effects of sidewall MOS channel on performance of AlGaN/GaN FinFET


Subthreshold slope of wide fin is lower than 60 mV/dec.

Subthreshold slope of narrow fin is higher than 200 mV/dec.

Wide fin exhibit severe hysteresis of threshold voltage.

Narrow fin exhibit negligible hysteresis of threshold voltage.

Trapping effect from sidewall is correlated to the fin width.



AlGaN/GaN FinFETs with various fin widths (Wfin), which have both a 2DEG channel and two sidewall MOS channels, have been fabricated by using electron-beam lithography and subsequent sidewall wet etch in tetramethyl ammonium hydroxide (TMAH) solution. The devices with wide Wfin of 150 nm showed normally-on operation with threshold voltage (Vth) of −2.5 and −5.0 V, respectively. The devices also exhibited broad transconductance (gm), and excellent off-state performance with very low subthreshold swing (SS). On the other hand, narrow device with Wfin of 50 nm exhibited normally-off operation with Vth of 3.0 V, but degraded SS due to trapping effect at the sidewall of fin.

Graphical abstract


Full-size image (28 K)



  • AlGaN/GaN
  • 2DEG
  • FinFET
  • Fin width
  • TMAH solution
  • Trapping/detrapping


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