Preparation and photoelectric properties of nanostructured native oxide of gallium monoselenide with applications in gas sensors

Abstract

Using the Bridgman technique, GaSe single crystals were obtained which were mechanically split into plane-parallel plates with a wide range of thicknesses. By heat treatment in air at 820 °C and 900 °C, for 30 min and 6 h, micro- and nanocomposite layers of Ga2Se3–Ga2O3 and β–Ga2O3 (native oxide) with surfaces made of nanowires/nanoribbons were obtained. The obtained composite Ga2Se3–Ga2O3 and nanostructured β–Ga2O3 are semiconductor materials with band gaps of 2.21 eV and 4.60 eV (gallium oxide) and photosensitivity bands in the green–red and ultraviolet-C regions that peaked at 590 nm and 262 nm. For an applied voltage of 50 V, the dark current in the photodetector based on the nanostructured β–Ga2O3 layer was of 8.0 × 10−13 A and increased to 9.5 × 10−8 A upon 200 s excitation with 254 nm-wavelength radiation with a power density of 15 mW/cm2. The increase and decrease in the photocurrent are described by an exponential function with time constants of τ1r = 0.92 s, τ2r = 14.0 s, τ1d = 2.18 s, τ2d = 24 s, τ1r = 0.88 s, τ2r = 12.2 s, τ1d = 1.69 s, and τ2d = 16.3 s, respectively, for the photodetector based on the Ga2Se3–Ga2S3–GaSe composite. Photoresistors based on the obtained Ga2Se3–Ga2O3 composite and nanostructured β–Ga2O3 layers show photosensitivity bands in the spectral range of electronic absorption bands of ozone in the same green–red and ultraviolet-C regions, and can serve as ozone sensors (detectors).