Pretreatment Effects on High-k/InxGa1–xAs MOS Interface Properties and Their Physical Model

The electrical and physical properties of atomic layer deposition high-k (Al
₂
O
₃
and HfO
₂
) /In
_x
Ga
_1-x
As (x = 0.53, 0.7, and 1) MOS interfaces with (NH
₄
)S
_y
, BHF, and HF pretreatment are examined. It is found that, as the In content (x) becomes higher, In
_x
Ga
_1-x
As MOS interfaces with BHF and HF cleaning show better C-V characteristics and lower interface state density (D
_it
) than with (NH
₄
)S
_y
pretreatment. Also, the amounts of arsenic oxides, evaluated by X-ray photoelectron spectroscopy, at the high In content Al
₂
O
₃
/In
_x
Ga
_1-x
As MOS interfaces are found to increase with BHF and HF cleaning than with (NH
₄
)S
_y
cleaning. These results suggest that arsenic oxides can contribute to passivation of high-k/In
_x
Ga
_1-x
As MOS interface defects and the decrease in D
_it
for x = 0.7 and 1. Finally, we propose a physical model to explain the relationship between possible interface defects responsible for D
_it
and the pretreatment effects with the different In contents.