Study On The Fabrication And The Properties Of Plasmonic Hot-electron Thin-film Transistor

With the development of optoelectronic technology,semiconductor photoelectric detection,as a vital part,has been widely used in national defense,military and national economy.But based on the semiconductor band theory,the semiconductor photodetectors can only detect the incident light with energy beyond the semiconductor band gap.Bing limited by the band gap of materials,wide-band-gap semiconductor can only respond in ultraviolet band,which limits its development and application.However,the usual way to change the band gap is to doping the material,the properties of the material will be changed.So,it is urgent to put forward new concepts and methods to solve the current difficulties.The appearance of plasmonics and the development of plasmon-induced hot electron provide a feasible method to solve this limitation.Surface plasmons(SPs)can manipulate light at nanometer length scales and the resonance wavelength can be effectively tuned by controlling the structure configuration.Optical detection using hot electrons has been around for a long time,but the low light absorption of metal leads to the low efficiency of the hot-electron detectors.Therefore,using plasmon-induced hot electron can effectively improve the efficiency of the detector.However,for this new type of hot-electron photodetection,the device excogitation,efficiency improvement,hot electron generation and transport mechanism still need a lot of in-depth research.In this thesis,the wide-band-gap semiconductor based metal-semiconductor-metal(MSM)photodetectors and thin film transistors are fabricated by thin film and micro / nano fabrication process.The effect of gold nanoparticles(Au NPs)on the photoelectric properties of the devices is studied.Through a series of preparation parameters optimization,the hot electrons generated by localized surface plasmons resonance(LSPR)of gold nanoparticles can be used for photodetection and improve the detection efficiency of the devices,which provides theoretical guidance and experimental proof for the development of new photodetectors.The main works in this thesis are listed as follows:(1)A ZnO thin film photodiode which has been decorated Au NPs was proposed with a comprehensive study on both the preparation process and performance optimization of ZnO thin film,including sputtering time,gas atmosphere,substrate temperature,annealing temperature,etc.The influence of Au NPs on the properties of ZnO was discussed by morphology,optical and electrical test.Ultimately,the windows of the ZnO detector extends from ultraviolet to visible band by using hot electron induced by LSPR of Au NPs.(2)The effects of preparation conditions(sputtering gas atmosphere,annealing temperature and sputtering thickness)on the properties of IGZO films were investigated and Au NPs decorated IGZO thin film transistors(TFT)were prepared.On the one hand,the plasmonic hot-electron structure can adjust the spectral response range of the phototransistor effectively.Regulation of the back gate voltage can also amplify the photocurrent and improve the quantum efficiency of the device.(3)The finite-difference time-domain(FDTD)simulation was implemented to explore the hot electron detection mechanism of IGZO TFT decorated with Au NPs.On the other hand,the influence of the metallic back gate on the optical properties of the device was analyzed.It is concluded that the metal back gate can effectively enhance the overall light absorption of the device and provide relevant guidance for later experiments.