Preparation of Sn-doped Ga2O3 thin films and their solar-blind photoelectric detection performance

Sn doping is an effective way to improve the response rate of Ga2O3 film based solar-blind detectors. In this paper, Sn-doped Ga2O3 films were prepared on a sapphire substrate by radio frequency magnetron sputtering. The films were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and ultraviolet visible spectroscopy, and the effect of annealing atmosphere on the properties of films was studied. The Ga2O3 films changed from amorphous to beta-Ga2O3 after annealing at 900 degrees C. The films were composed of micro crystalline particles with a diameter of about 5-20 nm. The beta-Ga2O3 had high transmittance for wavelengths above 300 nm, and obvious absorption for solar-blind signals at 200-280 nm. The metal semiconductor metal type solar-blind detectors were prepared. The detector based on Sn-doped beta-Ga2O3 thin film annealed in N-2 has the best response performance to 254 nm light. The photo-current is 10 mu A at 20 V, the dark-current is 5.76 pA, the photo dark current ratio is 1.7 x 10(6), the response rate is 12.47 A/W, the external quantum efficiency is 6.09 x 10(3)%, the specific detection rate is 2.61 x 10(12) Jones, the response time and recovery time are 378 and 90 ms, respectively.