Abstract:
In order to improve the performance of Ga
2O
3-based photodetectors (PDs), Sn-doped gallium oxide thin films were prepared on sapphire substrates by molecular beam epitaxy system. The influence of Sn doping on both Ga
2O
3 crystal structure and photoelectric properties of metal-semiconductor-metal (MSM) PDs were investigated. X-ray diffraction shows that gallium oxide films change from single crystal to polycrystalline phase when increasing the growth temperature of SnO
2. When 254 nm and 42 μW/cm
2 light was used, the responsivity of Sn-doped Ga
2O
3 photodetectors reached 444.51 A/W. Compared with the undoped β-Ga
2O
3 PDs, the photocurrent and responsivity of Sn-doped PDs were almost increased by two orders of magnitude, suggesting the improvement on PD performance. Spectral response shows that the cut-off wavelength of Sn-doped PDs changes from 252 nm to 274 nm by increasing Sn dose, which reveals an efficient way toward the development of the UV PDs focus on longer wavelengths. However, Sn doping also introduces impurity levels, resulting in poor time response of the MSM PDs.