HfO2-based In0.53Ga0.47As MOSFETs (EOT≈10Å) using various interfacial dielectric layers

This paper compares device performance for In
_0.53
Ga
_0.47
As MOSFETs using single HfO
₂
gate dielectric with stacked gate dielectrics using various interfacial layers between HfO
₂
and In
_0.53
Ga
_0.47
As substrate including Al
₂
O
₃
, HfAlO
_x
, LaAlO
_x
, and LaHfO
_x
. Of the gate stacks studied, Al
₂
O
₃
/HfO
₂
, HfAlO
_x
/HfO
₂
, and LaAlO
_x
/HfO
₂
bilayer gate dielectrics exhibit lower subthreshold swing, higher drive current and transconductance compared to single HfO
₂
with similar equivalent oxide thickness (EOT) of about 10 Å. This is believed to be due to better interface quality between interfacial dielectrics and substrate, and confirmed by frequency dispersion and interface state density measurements. Using 10 Å HfAlO
_x
or LaAlO
_x
as the interface layer between HfO
₂
and InGaAs substrate reduces the interface trap density, thus achieves higher drive current, channel mobility and lower subthreshold swing than single HfO
₂
layer.