Research On Diamond-based Solar-blind Photodetectors

Ultraviolet(UV)photodetectors have many civil and military applications such as biological/chemical analysis,flame sensing,covert space-to-space communications,missile tracking and environmental monitoring.Due to the strong absorption of deep UV light by ozone,particles,and water vapor in the atmosphere,the solar irradiation with wavelength shorter than 280 nm is almost non-existent at the surface of the earth,which is called solar-blind range.Owing to the low natural background in the solarblind region,photodetectors operating in this spectral range have high signal-to-noise ratio and low false alarm rate.Diamond has a variety of unique characteristics such as wide bandgap(5.47 e V),high thermal conductivity,high break-down voltage,high carrier mobility,and high radiation hardness,etc.,which makes it a promising candidate for solar-blind photodetection.To date,although many reports have demonstrated diamond based solar-blind photodetectors,the performance of these photodetectors is still far below expectation.The present work is focused on the subject of how to fabricate high performance diamond based solar-blind photodetectors.The following results have been achieved.1.Diamond-based photodetector with Au interdigital electrodes have fabricated.And the photodetector has very fast response speed.A solar-blind optical communication system has been constructed by employing the diamond photodetector as a signal receiver.The diamond photodetector was applied to the solar-blind communication system,and the output signals were consistent with the input signals.And then we fabricated a solar-blind warning device with diamond-based photodetector,and audible and visual alarm for the solar-blind signal was realized.2.All-carbon solar-blind photodetectors have been constructed based on the diamond with interdigitated graphite as electrodes.The graphite electrodes were made by laser induced graphitization of the diamond.The photodetectors have been employed as the sensing pixel in an imaging system,and clear image has been obtained,which is the first report on solar-blind imaging of diamond photodetectors.3.Diamond based photodetector with MSM structure was fabricated,and shows very high responsivity.The negative charges trapped by the surface sites.Owing to the Schottky barrier modulation,the photodetector shows very high responsivity and detectivity.