The Fabrication And Characterization Of ZnO-based Thin Film And Sandwich Structure UV Photodetectors

ZnO is a semiconductor material with a wide direct band gap and the detection range extend to short wavelength by alloying with Mg atom.Aiming at resolving the existed problem of the single structure and the low absorption of ZnO-based UV photodetecctors.Meanwhile,complying with the development demand of dual band detectors.In this paper,ZnO and MgZnO thin films have been achieved with controlling the growing parameters.On the basis of high quality thin films,ZnO/Au/ZnO,MgZnO/Au/MgZnO and ZnO/Au/MgZnO sandwich structure detectors have been designed.These detectors increased the metal-semiconductor contacting area and the effective area under incident light.We achievd and characterized the excellent performance and dual-wavelength UV photodetectors by the structure.The main researches are as follows:（1）Start with researching the structure of ZnO detectors,we constructed a neoteric sandwich structure of ZnO/Au/ZnO.The interlayer location of the Au electrodes bringed the high absorption of incident light and larger collection area of carries.The physical mechanism was analyzed that we characterized the effect of electric field and depletion width on the performance of sandwich structure detectors.The high performance of sandwich structure detectors was realized by changing the thickness of ZnO film,the space of interdigital electrodes and the thickness of Au.The responsivity of sandwich structure detector was increased 8 times compared to traditional ZnO/Au structure detectors.（2）Baesd on ZnO/Au/ZnO sandwich structure detector,MgZnO/Au/MgZnO sandwich structure detector was realized by alloying Mg element into ZnO.The structure overcame the high resistance and low responsivity of MgZnO detector.The responsivity of MgZnO/Au/MgZnO sandwich structure detector increased 6.2 times compared to the traditional MgZnO/Au structure detector.Through controlling the partial pressure（Ar:O₂）and the sputtering power of the radio frequency magnetron sputtering,the MgZnO/Au/MgZnO sandwich structure photodetectors with high crystallization property and excellent electrical performance was realized.（3）The innovative introduction of MgZnO/Au/ZnO and ZnO/Au/MgZnO sandwich structure detectors provided a novel and feasible method for broadening the application of dual-band UV detectors.We may conclued that the electrical performance of ZnO/Au/MgZnO detector is better than that of MgZnO/Au/ZnO detector by systemsical testing.Furthermore,the double responsivities of ZnO/Au/MgZnO detector included by the thickness of MgZnO layer were studied.Only by changing the applied voltage from 3 V to 15 V,the responsivity of the ZnO layer and the MgZnO layer were changed,roughly equal to 12.2 A/W and 11.9A/W,respectively.The as-prepared MgZnO/Au/ZnO sandwich structure detector providing a feasible application for the preparation of dual-band or multi-band detectors.