Comparison Study of β-Ga2O3 Photodetectors Grown on Sapphire at Different Oxygen Pressures

In this paper, β-Ga
₂
O
₃
ultraviolet photodetectors were grown on sapphire utilizing the laser molecular beam epitaxy tool. The impact of oxygen pressure P
_O2
in growth chamber on the crystal quality, the surface morphology, the chemical component of Ga
₂
O
₃
films, and the electrical performance of photodetectors are characterized. As the P
_O2
is increased during growth, the concentration of oxygen vacancy (V
_O
) is effectively reduced. The photodetector grown at the P
_O2
of 0.05 mbar exhibits the significantly improved photocurrent I
_photo
and responsivity R characteristics in comparison with the device grown with the P
_O2
of 0.01 mbar, which is attributed to a reduction in the number of V
_O
. However, as the P
_O2
continuously increased to 0.09 mbar, I
_photo
and R of the detector are degraded, which might be due to the fact that the gallium vacancies (V
_Ga
), as the dominant trapping centers, lead to the recombination of photo-generated carriers.