LAUSR

Recently, localized surface plasmon resonance of noble metal nanoparticles has been widely used to broaden the photoresponse of wide-band-gap semiconductors. In this work, Au nanoparticles with different sputtering time were prepared via ion sputtering and thermal treatment on ZnO thin films prepared by magnetron sputtering. The influence of the Au nanoparticle sputtering time on the absorbance of the Au/ZnO nanocomposite was investigated. The results show that Au/ZnO nanocomposites have enhanced UV absorption and broad absorption bands around 580–600 nm compared with ZnO without Au nanoparticles, which are attributed to the band-to-band excitation of ZnO and localized surface plasmon resonance of gold nanoparticles. Under the illumination of UV light, electrons are excited from the valence band to conduction band of ZnO, while hot electrons are transferred from Au nanoparticles with smaller particle size to ZnO, resulting in the generation of photocurrent. Under the illumination of visible light, only hot electrons are transferred from Au nanoparticles with larger particle size to ZnO, leading to the generation of photocurrent. Then the influence of sputtering time on the dark current and IXenon lamp/IDark of the photodetectors was investigated. The results show that Au nanoparticles are able to decrease the dark current of photodetectors and influence the photoresponse under visible light illumination.