Preparation And Characterization Of Ultraviolet Detector Based On Interdigital Electrode

Ultraviolet detection technology is a new dual-use technology developed after infrared and laser detection technique,which has been widely used and deeply studied in more and more fields.Ultraviolet detector can be used for missile early-warning in the military field.In 1980 s,the military research of ultraviolet detection technology has been started in foreign countries,and some progress has been made.In the civil field,ultraviolet detection can be used to monitor the thickness of ozone layer,discharge of pollutants,and detection of corona discharge phenomena in various high-voltage facilities,and so on.At present,the research of ultraviolet detector is mostly focused on photochromics.However,the structure of the device is less studied.Furthermore,the electrode structure of MSM UV-detector not only affects the incident and absorption of light,but also affects the electric field distribution of the device.Therefore,different electrode mechanisms will affect the performance of UV-detector.Based on this,the effects of different electrode structures on the characteristics of MSM UV-detectors are studied by means of device simulation and fabrication in this paper.The main results are listed as follows:1.The ISE-TCAD software is used to simulate and optimize the device,and the influence of the interDigital electrode width and the interdigital distance on the light/ dark current of the UV detector has been discuss.Based on the basic semiconductor equations such as Poisson equation,carrier continuity equation,current density equation and so on,the drift-diffusion model and compound model are established.On the basis of this,the effects of the electrode width and interdigital distance of the Al-ZnO-Al structure and the interDigital electrode of the Au-ZnO-Au structure on the light / dark current of the device are investigated by using the ISE-TCAD device simulation software.2.Al-ZnO-Al MSM UV detectors with different structure parameters were fabricated by photolithography,magnetron sputtering and photolithography on silicon substrate.The effects of electrode structure on steady-state current-voltage characteristics,switching characteristics and spectral response characteristics of ohmic contact MSM ultraviolet detectors were investigated.The factors that affect the switching characteristics of the device are also studied.The results show that the Al with the purity of 99.99%ZnO can form an ideal ohm contact.The dark current of the device is influenced by the width of the interDigital electrode,but is independent of the the interdigital distance.The photoelectric current increases with the increase of the the interdigital distance.When the width of interDigital electrode is 200?m and the distance of the interDigital electrode is 600?m,the light / dark current ratio of the device is up to 156.The structural parameters of the electrode have no obvious influence on the switching characteristics of the UV detector.The rise time of the detector is about 56 s,and the drop time is 141 s.In addition,the device has the strongest response to the ultraviolet light around 370nm3.Au interdigital electrode was fabricated on the surface of ZnO to study the influence of msm UV detectors with different structure parameters on the steady voltage DC characteristics,switching response characteristics and spectral response characteristics of Schottky contact MSM UV detectors.The experiments show that a good Schottky contact can be formed with the purity of 99.99%ZnO.In addition,the interdigital electrode spacing has no obvious effect on the dark current of the device.When the bias voltage increases from 0 V to| |,the dark current of the device increases sharply,and the dark current is about 15 pA at the 5 V bias voltage.The photocurrent of the device increases with the increase of the interDigital electrode spacing.The light /dark current of the device is up to 132,when the distance of the interdigital electrode is 600?m.In addition,both the dark current and the photocurrent of the device increase with the width of the interdigital electrode.The ratio of light / dark current decreases with the increase of electrode width.The rising time of the detector is 3.4 s and the falling time is 5.3 s.The response time is shorter than that of Al-ZnO-Al photoconductive UV detector.In addition,the switch characteristics of the detector mainly depend on the carrier life.However,it has little to do with the structure of the device.