The effect of Ga-doped nanocrystalline ZnO electrode on deep-ultraviolet enhanced GaN photodetector

Two types of GaN-based ultraviolet (UV) photodetectors were fabricated by using NiAu and Ga-doped ZnO (GZO) as electrode materials, respectively. Dark current-voltage and photoresponse characteristics of the devices were investigated. It is found that in addition to the similar to 365 nm cut-off response of GaN, an enhanced responsivity at around 250 nm is achieved for the GZO/GaN photodetectors. Photo absorption measurements provide proof that the efficient deep UV absorption occurs in the solar blind spectral zone. Transmission electron microscopy observations reveal the existence of nanostructures in the GZO thin film. Such nanostructures could be responsible for the deep UV photoresponse. (C) 2013 AIP Publishing LLC.