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

Abstract

In this letter, we demonstrate an efficient way to modulate the threshold voltage ( ${V} _{\text T}$ ) 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- $\mu \text{m}$ gate-length device exhibits positive ${V} _{\text T}$ shift of 2.98 V from planar to fin device with a fin width ( ${W}_{\text {FIN}}$ ) of 54 nm, and an enhancement-mode operation is achieved when ${W}_{\text {FIN}}$ is less than 74 nm. Performances are enhanced both for ON-and OFF-state with ${W}_{\text {FIN}}$ 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.