Preparation And Application In Transistors Of SnO₂ Nanowires

Nano-materials have gained a tremendous amount of attention due to their novel physical and chemical properties which are different from their corresponding bulk materials. The thesis reports fabrication of undoped SnO₂ nanowire and in-situ doping of Sb element into SnO₂ nanowires via Chemical Vapor Deposition (CVD) method with Vapor-Liquid-Solid (VLS) technique. High Resolution Transimission Electron Microscopy (HRTEM) was applied to characterize the structure of one-dimensional SnO₂ nanostructures, and good crystallinity was proved by HRTEM. The electrical characteristics of SnO₂ nanowires can be reasonable controlled through doping. The undoped SnO₂ nanowires show Schottky contact to Ti/Au electrodes in air and are suitable for the detection of UV light. Lightly Sb-doped nanowires are promising as high-performance nanowires transistors, and degenerately Sb-doped SnO₂ nanowires are transparent metallic conductors.A gold microwire mask method is developed for the fabrication of transistors (FETs) based on single lightly Sb-doped SnO₂ nanowires. Damage and disadvantage touch of the nanowire's surface can be avoided without any thermal annealing and surface modification, which is very convenient for the fundamental electrical and photoelectric characterization of one-dimensional inorganic nanomaterials. Transport measurements of the individual SnO₂ nanowire device demonstrate the high-performance n-type field effect transistor characteristics without significant hysteresis in the transfer curves. The current on/off ratio and the subthreshold swing of the nanowire transistors are found to be 106 and 240mV/decade, respectively. Compared to traditional 1D inorganic nanomaterials FETs fabrication techniques, the advantages of our fabrication method have been listed as follows: a) No lithographic tools are used, it is very appropriate to fundamental research because the entire process of fabrication method is very simple and little equipment is needed. b) In the process of the electrode deposition without radiation damage, which benefit to improve the device performance. c) Any nanowire can be flexibly selected and used for fabricating functional devices in specific area which we are interested in. d) The configuration of the nanodevice (such as symmetrical or asymmetrical source/drain electrodes) and the length of active channels can be effectively adjusted.The key advantage of the nanowires thin film transistors (TFTs) approach compared to conventional TFT techniques is the clear separation of the device fabrication stage from the material growth stage, such that there is no longer need to be concerned with compatibility with the device substrate during growth, and high growth temperature can be used to obtain crystalline materials. The gold microwire mask method was also employed for the fabrication of SnO₂ nanowires TFT, this device shows high-performance, the current on/off ratio and subthreshold are found to be 10⁵, and 2.3V/decade.