Fabrication And Characterization Of A Single InAs Nanowire Photodetector

Low dimensional semiconductor structures have a lot of advantages,among which the semiconductor nano wires(NWs)(or quantum wires)have an extensive application prospect in the next generation of electronic and optoelectronic devices and systems due to their unique characteristics.The NWs fabricated by "bottom-up" epitaxial growth have many excellent properties,including high crystal quality,controllable growth direction,the ability to form ordered self supporting NW arrays and be integrated.At the present stage,the technology of NWs growth has become mature,and the research area of NWS has turned to the application of NWs devices.A variety of functional devices have been achieved,including NW lasers,NW photodetectors,NW sensors,NW light-emitting diodes,NW solar cells and so on.This dissertation focuses on the fabrication and characterization of InAs NW detectors and the main research results are as follows:1.The methods and techniques for NW epitaxial growth are summarized,as well as the commonly used Characterization methods and the applications in photodetectors of the NWs.2.InAs NWs are fabricated by Metalorganic Chemical Vapor Deposition(MOCVD)and their morphology and crystal structure are characterized.The InAs NWs have cone shaped structures and have wurtzite(WZ)crystal structures,with a large stacking fault density.3.The preparation process of single InAs NW detectors are explored,including lithography,plasma stripping,etch,passivation and fabrication of metal electrode.And InAs NWs detectors are fabricated.4.The I-V characteristics of the single InAs NWs detectors are measured.The result shows that without illumination,under low bias voltage,the current increase slowly with the increase of the voltage.But after the voltage exceeds a specific value,the current increase significantly with the voltage.At low illumination intensities,the current is smaller than that without illumination,while under high illumination intensities,the current increase with the light intensity.And a reasonable theoretical explanation of this phenomenon is given in the main text.