Threshold Voltage Modulation of Enhancement-Mode InGaAs Schottky-Gate Fin-HEMTs

In this letter, we demonstrate an efficient way to modulate the threshold voltage (V
_T
) of InGaAs high-electron-mobility transistors (HEMTs) through forming the fin-shaped channel. The gate metal is directly deposited on this fin-shaped channel and thus can be regarded as a “Schottky-gate Fin-HEMT.” The device exhibits great fabrication stability and electrical characteristics. The 2-μm gate-length device exhibits positive V
_T
shift of 2.98 V from planar to fin device with a fin width (W
_FIN
) of 54 nm, and an enhancement-mode operation is achieved when W
_FIN
is less than 74 nm. Performances are enhanced both for ON-and OFF-state with W
_FIN
scaling down to the regime of about 100 nm. The modulation mechanism can be attributed to the band bending at metal-semiconductor interface of the side gate, which is verified by the TCAD simulation, and thus depletes the carriers channel much more efficiently than top gate control.