Wide bandgap semiconductor ZnO has been intensively studied for its potential applications in the area of ultraviolet (UV) optoelectronics

such as UV detection and UV Emission. ZnO films are promising for high efficiency UV optoelectronic applications due to its wide direct band gap of 3.37 eV at room temperature and large excitonic binding energy of 60 meV. Naturally

high quality Ohmic and Schottky contacts are necessary for commercial produce of ZnO based optoelectronic and electronic devices

such as ZnO UV photodetector. At present

the structures of ZnO photodetectors almost are metal-semiconductor-metal (MSM) Schottky or Ohmic contact surface structure. It is hard to be used for further ZnO UV detector array and single photon detector

and reflection or shelter effect of electrode can reduce the utilization efficiency of incident light. In this paper

a back-illuminated Au/ZnO/Al Shottky UV photodetector was designed and fabricated. It is a vertical structure device. The rounded Al window electrode as Ohmic contact was fabricated on sapphire at first

then ZnO film was grown on sapphire with Al window electrode by radio frequency magnetron sputtering

at the same time

sapphire in the widow also was used for protected layer. At last

the rounded Au electrode was fabricated on 50 nm Au layer by conventional UV photolithography and wet etching. The objective was to use Au as Schottky contact. The diameters of Al window and Au electrode are 950 m. On

I-V

curve of Au/ZnO/Al was measured by an HMS 7707 Hall measurement system (Lakeshore)

a clear rectifying effect caused by Au/ZnO Schottky barrier was found. It was showed that we have got well Au/ZnO Schottky contact and ZnO/Al Ohmic contact. The insert light was led-in device from Al window. The peak responsivity wavelength is located at 352 nm

and the cutoff wavelength is 382 nm

UV/visible rejection ratio is only one order of magnitude. Due to the device structure is vertical type

it will be valuable for further ZnO UV detector array and single photo detector study.