背入射Au/ZnO/Al结构肖特基紫外探测器

A Back-illuminated Au/ZnO/Al Shottky UV Photodetector

设计制作了一种Au/ZnO/Al结构的紫外探测器,光的入射方式采用背入射式。ZnO薄膜是用磁控溅射在蓝宝石衬底上制备的。I-V测试表明：Au与ZnO形成了肖特基接触。得到探测器的光响应峰值在352nm,截止边为382nm,可见抑制比达一个量级。由于该探测器是一种垂直结构器件,对于进一步实现ZnO紫外探测器阵列及单光子探测有很好的研究价值。

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 μm.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.