High-performance photodetector based on sol–gel epitaxially grown α/β Ga2O3 thin films

Ga2O3 has been receiving more and more attention for solar blind photodetectors due to it has a large direct bandgap corresponding to solar blind waveband. However, numerous photodetectors based on single crystalline Ga2O3 exhibited a relatively large dark current and a low photo-to-dark current ratio. Herein, the α/β phase polycrystalline Ga2O3 thin film was successfully synthesized via sol-gel method and the photodetector with low dark current(18.5 pA at 15 V) and high photo-to-dark current ratio(1664) was further fabricated. By optimizing annealing environment, the photodetector also exhibited an excellent detectivity (D*) of 5.41×1011 Jones and a fast photo-response speed (a rise time of 0.03 s/0.23 s and a decay time of 0.04 s/0.41 s). Excellent performance can be ascribed to that tailoring of the defect concentration in the polycrystalline Ga2O3 film by introducing α-Ga2O3 into β-Ga2O3 and the physical mechanism was discussed with a carrier transport model. The experimental results suggested the great potential applications of Ga2O3 thin films synthesized by the sol-gel method in ultraviolet detection and our experiment reveals an effective method for manufacturing high-performance solar-blind photodetectors.