Enhancement-Mode Antimonide Quantum-Well MOSFETs With High Electron Mobility and Gigahertz Small-Signal Switching Performance

This letter demonstrates, for the first time, enhancement-mode (e-mode) antimonide MOSFETs by integrating a composite high-κ gate stack (3 nm Al
₂
O
₃
-1 nm GaSb) with an ultrathin InAs
_0.7
Sb
_0.3
quantum well (7.5 nm). The MOSFET exhibits record high electron drift mobility of 5200 cm
²
/V · s at carrier density (N
_s
) of 1.8 × 10
¹²
cm
^-2
, subthreshold slope of 150 mV/dec, I
_ON
/I
_OFF
ratio of ~4000× within a voltage window of ~1 V, high I
_ON
of 40 μA/μm at V
_DS
of 0.5 V for a 5-μm gate length (L
_G
) device. The device exhibits excellent pinchoff in the output characteristics with no evidence of impact ionization enabled by enhanced quantization and e-mode operation. RF characterization allows extraction of the intrinsic device metrics (C
_gs
, C
_gd
, g
_m
, v
_eff
and f
_t
) and the parasitic resistive and capacitive elements limiting the short-channel device performance.