Effects of ZnO seed layer thickness on catalyst-free growth of ZnO nanostructures for enhanced UV photoresponse

Abstract

Catalyst-free growth of ZnO nanostructures were synthesized on ZnO seed layers with different thickness (25–150nm) coated glass substrates by thermal evaporation method. Prior to the growth process, the sputtered ZnO seed layers were annealed using the continuous wave CO2 laser asa heat source at 450°C in air for 15min. The fabrication and characterization of a metal–semiconductor–metal ultraviolet photodetectors based on ZnO nanostructures with different thickness of seed layer were successfully fabricated. Upon exposure to 365nm light (1.5mW/cm2) at five-bias voltage, the device with 100nm thick seed layer showed a relatively high UV sensitivity, quick response, and high responsivity. The prototype device shows a cost effective glass substrate using thermal evaporation method for ZnO nanostructures synthesis and demonstrates the possibility of constructing nanoscale photodetectors for nano-optics applications.