Design?Preparation And Characteristics Of Double-layer MgZnO Solar Blind UV Detector

The solar blind UV detector has a wide application prospect.Among multiple types of UV sensitive semiconductor materials,MgZnO material own relative a higher sensitivity at UV light and a wide detectable UV light rang,which makes MgZnO as an ideal materials in high performance UV detctors.In recent years,it has been found out that the detector with two-dimensional electron gas mechanism has an outstanding higher UV response and a lower dark current(I_dark)than the other structure detectors.In this paper,combining the advantages of two-dimensional electron gas mechanism and the good performance of MgZnO material in UV detection,the double-layer structure detectors are made on MgZnO material,and the effect of two-dimensional electron gas mechanism on the UV response,I_dark and signal-to-noise ratio of MgZnO detector will be studied,the main content in this paper are listed as follows:(1)Effects of defferent oxygen pressure on the band gap,crystal structure and optical properties of MgZnO films that deposited by Pulse laser deposition(PLD)method on quartz and Mg O substrates were studied.With the increase of oxygen pressure,the MgZnO thin films deposited mainly along cubic structure on fused quartz substrate.The relative Mg content in MgZnO thin films decreases gradually,and the band gap of MgZnO thin films decreases continuously.With the increase of oxygen pressure,MgZnO thin films deposited along(200)orientation of cubic MgZnO on Mg O substrate,the crystal quality of MgZnO film is improved,and the band gap of MgZnO thin films decreases gradually.(2)Effects of defferent growth temperature on the band gap,crystal structure and optical properties of MgZnO films that deposited by Pulse laser deposition(PLD)method on quartz and Mg O substrates were studied.When the depostion temperature increased from 300?to 500?,the MgZnO thin films deposited less along(200)cubic structure and more along(0002)hexagonal structure.When the depostion temperature increased from 500?to 570?,the MgZnO thin films deposited less along(0002)hexagonal structure and more along(111) cubic structure.When the quartz growth temperature is 500?,the response of MgZnO solar blind UV detector is 115.75 A/W at 250 nm ultraviolet lingt under 25V bias voltage.With the growth temperature increased,MgZnO thin films deposited along(200)orientation of cubic MgZnO on Mg O substrate,the crystal quality of MgZnO thin films increased.The crystal quality of MgZnO film deposited at 570?is relative higher.(3)The effect of the thickness of top Mg_xZn_1-xO layer on the performance of the double-layer MgZnO UV detectors are studied.When the thickness of top Mg_xZn_1-xO layer is about 30 nm,the responsivity of UV detector is 0.82 A/W under 265 nm UV irradiation;and the dark current is 10^-11 A at 25 V bias;the maximum signal-noise ratio is 2.8×10⁵.Compared with the single-layer MgZnO solar blind UV detector grown under the same conditions,the responsivity is increased by 1177 times,and the signal-noise ratio is increased by about 10⁵ times.