Amorphous InGaZnO Ultraviolet Phototransistors With a Thin Ga2O3 Layer

The authors report the fabrication of amorphous IGZO (a-IGZO) phototransistors with a thin Ga
₂
O
₃
layer. It was found that the performances of the phototransistors depend strongly on the oxygen partial pressure during the deposition of the Ga
₂
O
₃
layer. It was also found that the fabricated devices exhibited good electrical properties with electron mobility (μ
_FE
) of 13.2 cm
²
/V·s, subthreshold swing (SS) of 0.13 V/decade, and ON/OFF current ratio> 5 × 10
⁵
. Furthermore, it was found that two cutoffs exist in the devices prepared with 25% oxygen partial pressure. The deep-ultraviolet (UV)-to-visible rejection ratio and near-UV-to-visible rejection ratio of the fabricated phototransistors were 10
⁴
and 20, respectively.