Effect of Interface States on the Performance of Antimonide nMOSFETs

Antimonide (Sb) quantum-well MOSFETs are demonstrated with an integrated high- κ dielectric (1-nm Al
₂
O
₃
/10-nm HfO
₂
). The effect of interface trap density
D
_it
on the dc drive current and transconductance
gm
is studied in detail using split
C
-
V
/
G
-
V
, pulsed
I
-
V
, and radio-frequency measurements. Pulsed
I
-
V
measurements show improved on current, transconductance, and subthreshold slope due to reduced charge trapping in the dielectric at high frequencies. The long-channel Sb nMOSFET exhibits effective electron mobility of 6000 cm
²
/V·s at high field (2 × 10
¹²
/cm
²
of charge density
Ns
), which is 15× higher than Si NMOS inversion layer mobility, and one of the highest values reported for III-V MOSFETs. The short-channel Sb nMOSFET (
LG
= 150 nm) exhibits a cutoff frequency
fT
of 120 GHz, an
fT
×
LG
product of 18 GHz·μm , and a source-side injection velocity
v
_eff
of 2.7 × 10
⁷
cm/s at a drain bias
V
_DS
of 0.75 V and a gate overdrive of 0.6 V.