Correlation between channel mobility improvements and negative Vth shifts in III–V MISFETs: Dipole fluctuation as new scattering mechanism

Channel mobility µ
eff
for InGaAs MISFETs is improved by using the (111)A surface orientation and (NH
4
)
2
S treatment. These µ
eff
improvements are associated with negative shifts in V
th
and V
fb
. We propose that carrier scattering by fluctuated dipoles at the MIS interfaces contributes to µ
eff
for the III–V MISFETs. For the InP MISFETs, the effects of the interface dipoles are not apparent due to their inferior interface quality.