Anisotropic optical properties and polarization-sensitive solar-blind photodetector of polycrystalline Ga₂O₃

Gallium oxide (Ga 2 O 3 ), as one of typical ultrawide bandgap semiconductors, has been extensively employed to fabricate authentic solar-blind ultraviolet photodetectors, owing to its bandgap of around 4.9 eV and absorbance cut-off wavelength of 280 nm. It exhibits advantage of materials in nature, compared to some other multi-element alloyed semiconductors. Currently, most reports on Ga 2 O 3 -based photodetectors are focused on sensing light wavelength and intensity. However, light carriers additional third semantide, i.e., polarization state. In this work, a solar-blind deep ultraviolet photodetector based on plasma-enhanced chemical vapor deposition (PECVD)-grown polyscrstalline Ga 2 O 3 thin film is fabricated and analysed, for sensing the wavelength, intensity and polarization state of incident ultraviolet light. The dark current is as low as 7.1 × 10 −13 A, responsivity is 189 mA W −1 , specific detectivity is ∼10 13 Jones and external quantum efficiency is 30%. This photodetector could display good performance for sensing the light wavelength and light intensity. Moreover, the angle-resolved polarization Raman spectroscopy (ARPRS) is used to analyse the anisotropic optical properties of prepared Ga 2 O 3 thin film. And, the polarization state photodetection is measured and discussed in detail, the polarization dichroic ratio is ∼1.3, indicating an ability to perform anisotropic optical photodetection.