Interfacial engineering of InGaAs/high-k metal-oxide-semiconductor field effect transistors (MOSFETs)

The electrical properties of In
_x
Ga
_1-x
As (x=0.53, x=0.65) MOSFETs have been studied for three different ex-situ surface passivation techniques (HF clean, (NH
₄
)
₂
S clean and PECVD a-Si interlayer) with HfO
₂
gate dielectric (4 nm and 8 nm) and Ni/Au gate metal. In
_0.65
Ga
_0.35
As devices demonstrate much higher drive current than In
_0.53
Ga
_0.47
As devices. Devices with an a-Si IPL exhibit the highest drive current and mobility, whereas (NH
₄
)
₂
S surface cleaned devices show higher drive current, trans-conductance and mobility compared to HF cleaned devices. Also devices with a-Si IPL and (NH
₄
)
₂
S clean shows the highest and the lowest sub-threshold swing, respectively. Furthermore charge pumping measurements show a similar average mid-gap D
_it
indicating that mid-gap D
_it
is not related to the improvement in transport characteristics.