Optoelectronic characteristics of UV photodetectors based on sol–gel synthesized GZO semiconductor thin films

Abstract

Ga-doped ZnO (GZO), B–Ga codoped ZnO (GZO:B), and Al–Ga codoped ZnO (GZO:Al) transparent semiconductor thin films and photoconductive ultraviolet (UV) detectors were fabricated on alkali-free glass substrates by the sol–gel route. The doping concentration of Ga was 0.5at.%, and that of Ga plus B or Al was 1at.% in the precursor solutions. The structural, electrical, and optical properties of GZO, GZO:B and GZO:Al thin films were compared and the photoconductivity and photoresponsivity of ZnO-based UV photodetectors are reported. All as-prepared ZnO-based thin films had high transparency in the visible region, and the GZO:Al thin film exhibited the best electrical properties. Current–voltage (I–V) characteristics in dark and illuminated conditions showed that the resistance of the films fell by more than an order of magnitude upon UV light illumination. In this study, we found that the photoconductive UV detector based on GZO:Al film exhibited the highest responsivity, 3.22A/W at 5V bias under UV light illumination.