High-performance energy-efficient solar-blind photodetector based on non-doped nano-crystalline gallium oxide films

We have fabricated simple, cost-efficient metal-semiconductor-metal photodetector based on ultra-high pure non-doped nano-crystalline gallium oxide films deposited at room temperature by electron beam evaporation. The key photodetector parameters, the parameter trade-offs and the device performance reliability have been experimentally studied as a function of annealing temperature and time, film thickness, electrode geometry, electric field strength and operation temperature. The devices demonstrate properties of high-performance intrinsic photo-resistors including high responsivity, quantum efficiency and detectivity. The essential features of these photodetectors are high photocurrent to dark current ratio (≥ 10 5 ) and superiorly short rise/decay times (500 μs/dec) under ultra-violet (UV) illumination with the wavelength of ≤253 nm. It is established that the post deposition annealing conditions are critical for initiation of transition from amorphous GaO x to nano-crystalline GaO x (111) phase which results in elimination of deep level traps within the gallium oxide band gap and achieving the properties of high performance solar blind detector. The key performance parameters, such as responsivity of 3.5 A/W and 12.5 A/W, detectivity of 8.5 × 10 12 Jones and 2.2 × 10 12 Jones and quantum efficiency of 1.6 × 10 3 % and 6.1 × 10 3 % were achieved at as low operating voltage as 0.5 and to 2.0 V, respectively, that is suitable for fabricating compact energy efficient solar blind UV photodetectors. To mitigate a reliability issue for photodetector working under a constant bias, the method of photocurrent registration under UV illumination using electronic chopper has been developed.