Ultraviolet photoconductive detector based on epitaxial Mg0.34Zn0.66O thin films

We report on the fabrication and characterization of visible blind ultraviolet photodetectors based on ${\mathrm{Mg}}_x{\mathrm{Zn}}_{\text{1−x}}\mathrm{O}.$ Using pulsed laser deposition technique, ${\mathrm{Mg}}_{\mathrm{0.34}}{\mathrm{Zn}}_{\mathrm{0.66}}\mathrm{O}$ thin films with a bandgap of 4.05 eV were epitaxially grown on c-plane sapphire substrates. The structural, electrical, and optical properties of epilayers were characterized using various techniques. Based on the ${\mathrm{Mg}}_{\mathrm{0.34}}{\mathrm{Zn}}_{\mathrm{0.66}}\mathrm{O}$ films, planar geometry photconductive type metal–semiconductor–metal photodetectors were fabricated. At a 5 V bias, a high responsivity of 1200 A/W was achieved at 308 nm, and the visible rejection (R308 nm/R400 nm) was more than four orders of magnitude. The 10%–90% rise and fall time were 8 ns and 1.4 μs, respectively.