Low-Dimensional Composite Material Photodetector

Since the discovery of graphene,it has rapidly become a hotspot in the field of materials science,physics and electronics due to its excellent optical,electrical,thermal and mechanical properties.In view of the excellent properties such as zero band gap,high carrier mobility,high transmittance,wide absorption spectra and Quantum Hall Effect at room temperature,graphene has been of significant research value and application prospect in wide spectrum,high electrical responsivity and non-refrigerated photoelectric detector parts.However,the structure of grapheme of zero-band gap makes the light absorption efficiency low and the separation area of the photogenic carrier small,which leads to the difficulty in extracting and thus the detection inefficiency.It leads to low responsiveness and quantum efficiency of graphene photodetector parts.Aiming to solve the above problems,researchers have constantly explored new methods,such as designing new photoelectric detector parts,introducing new materials,etc.Under the above background,the study chose the nanometer titanium dioxide,nanometer lead sulfide to compound with grapheme.Photodetectors of lead sulfide/titanium dioxide/graphene composite materials were prepared by controlling the process parameters and designing the device structure,followed by the further exploration into the effects of experimental parameters on device performance.The main work results are summarized as follows:?1?Controllable preparation of graphene by Atmospheric Pressure Chemical Vapor DepositionThrough the growth of copper foil substrate pretreatment,the paper carries on an analytical study on the growth temperature and growth time in the growing process.At a temperature of 1050?and a growth time of 60 min,single-layer graphene film of 2 cm×5cm could be prepared.When the temperature is 1075?was combined with a growth time of 60 min,monocrystalline graphene of a size of 800?m submillimeter could be derived.The protective effect of PMMA on graphene was utilized to transfer the non-destruction of graphene to Si O₂/Si substrate by wet processing for device preparation.By means of optical microscopy and Raman spectra,the post-transferring graphite is proved to be graphene of high quality.?2?Research on graphene photodetectorOn the basis of the nondestructive transfer of graphene,the preparation of graphene field effect photoelectric detector was focused on through improved photolithography process,double-layered gelling photolithography process and evaporation process,obtaining the photodetector with intact electrode stripping and lossless belt of grapheme.The electrical properties of the test device illustrated that graphene has the bipolar characteristics of hole and electron.The optical performance of device was tested,finding that the optical responsivity of the graphene photodetector reached 10 mA/W with the laser of 635 nm,and the device could get a larger photoelectric current when the temperature was less than 150 K.?3?Research on preparation and properties of PbS/Ti O₂/G of low-dimensional composite photodetectorsPbS monocrystalline nanoparticles were controllably prepared by electrochemical atomic layer epitaxy based on the underpotential behavior of Pb²⁺and S²⁺in PbS on titania-graphene composite films.Subsequently,the photoelectric detector of PbS/Ti O₂/G composite materials was prepared by utilizing the photolithography and electrochemical deposition processes.The results of the photoelectric performance measurement and study show that the responsivity of the photodetector is 1.38×10⁵ A/W and the response time is 30ms.The Photogating Effect of the device is determined to be the operating principle of device after analyzing the test of the transfer characteristic curve of the device.