Hydrogen Plasma Etching Of Diamond Catalysed By Metal And The Application In Fabricating Ultraviolet Detector

Diamond exhibits many excellent properties,including high thermal conductivity,low dielectric constant,high break-down voltage,high carrier mobility and high radiation resistance,which make it a promising material for high-power semiconductor devices and detectors.Although the traditional silicon ultraviolet(UV)detector technology is mature,its disadvantages,such as low sensitivity to UV light,low selectivity of UV/visible light and low resistance under deep UV radiation,which will reduce the lifetime of detectors,make it inappropriate used in detectors of missiles,air quality and the amount of UV radiation.Diamond,with a wide forbidden band,is able to solve the problem by refusing the response to visible light and eliminate the interference.However,the early solution way is fabricating the plane UV detectors using diamond directly with no pretreatment.The superior properties of diamond are wasted because of the irrational structures.To solve this problem,etch of diamond before the process and fabrication of 3-D electrodes to improve the performance of UV detectors are proposed.Although it is possible,the new problem,high cost and difficulty of diamond processing,restricts its application.In this work,the etch of single-crystal diamond catalysed by metal(especially iron) under hydrogen plasma activated by microwave plasma-assisted chemical vapor deposition(MPCVD)was investigated and further improved to obtain an applicable diamond etching technique.The novel use of etch make it possible not only saving the cost but also to combine the two steps together,which is good for simplify the procedures.Furthermore,this method is safer than heating hydrogen and the etch surfaces are more smooth.The physical mechanisms of diamond etch catalysed by metal are also investigated using SEM,EDS,XPS,XRD and TEM.Crystallography is used to explain the difference of etch surface of different oriented diamond and make it possible to improve the technique.The etch surfaces and sidewalls of {111}-oriented diamond were smooth and vertical.Then the novel technique was implemented in fabricating diamond 3-D UV detector.The performance of 3-D detector was tested and compared with that of traditional plane one.The result shows an obvious superiority of the former and the performance was improved by 1-3 orders.