Effect of Gate Voltage Stress on InGaAs MOSFET With HfO2 or Al2O3 Dielectric

InGaAs nMOSFETs with Al
₂
O
₃
and HfO
₂
as dielectric are analyzed. The devices with Al
₂
O
₃
show a slightly better subthreshold slope. Both high-κ's have an equal transconductance frequency dispersion (g
_m
-f). A reduction of g
_m
-f is reached by scaling the HfO
₂
thickness. Positive gate stress leads to an increase in threshold voltage and subthreshold slope for all oxides. DC-g
_max
degradation is related purely to creation or activation of additional border traps during stress. The RF-g
_max
is not degraded. Similar time constants hint to a relation between the (semi-)stable degradation of DC-g
_max
and the threshold voltage increase. For the samples with HfO
₂
, the effects of gate-stress induced additional border traps can only be detected at low frequencies. The created or activated defects are most likely located deep in the oxide. For Al
₂
O
₃
, the effect of additional border traps is also measurable at higher frequencies. The defects are created both closer to the Al
₂
O
₃
/InGaAs interface and deeper in the oxide.