Extraction of Channel Electron Effective Mobility in InGaAs/Al $_{\bf 2}$O$_{\bf 3}$ n-FinFETs

A compact set of equations based on the multiple subbands quasi-ballistic transport theory is developed, and is used to investigate the channel electron effective mobility in recently reported In
_0.53
Ga
_0.47
As/Al
₂
O
₃
tri-gate n-FinFET. The extracted electron effective mobility μn is around 370 cm
²
/V·s at low V
_g
- V
_th
bias at room temperature and decreases with increasing V
_g
, and increases with increasing temperature (240-332K). It is very different from the case of Si n-MOSFETs, where the electron mobility decreases with increasing temperature. The low channel effective mobility and the ab-normal temperature dependence of μ
_n
are ascribed to the high acceptor interface trap and border trap energy densities in the conduction band energy of InGaAs. The ballistic channel resistance R
_Ball
at low Vds is calculated and compared with the measured channel resistance R
_CH
. The low transmission coefficient T = R
_Ball
/R
_CH
≈ 0.06 to 0.05 indicates that there is a large room to improve the InGaAs/Al
₂
O
₃
n-FinFET performance.