The Studies On The UV Photodetector And Resistive Random Access Memory Of ZnO Nanowire Shottky Barrier

In this paper, we studied the effects of adsorbed oxygen of nanowire surface on the Schottky Barrier (SB). By using ultra violet (UV) to achieve effective regulation of oxygen adsorption and SB height, on the basis, the ZnO nanowire Schottky barrier UV detector with high sensitivity and fast recovery time is developed. In addition, we also studied the effects of oxygen vacancy of nanowire surface on the SB. We used pulse voltage to achieve regulation of concentration of oxygen vacancy on the interface, and on the base of which the ZnO nanowire Schottky barrier resistive switch random access memory with fast write time and high read out window is developed.In the first chapter the optoelectronic devices of one-dimensional, including one-dimensional photodetectors and resistance switch random access memory were introduced. The current research and key problems about single nanowire SB UV detector and resistive switch memory were mainly discussed.In the second chapter we described the synthesis of ZnO nanowires. The ZnO nanowire were grown on single Si (100) crystal substrate by Au catalyst assisted vapor liquid solid (VLS). The UV detectors and resistive switch memorys based devices were fabricated by aligning single ZnO nanowires across paired Au electrodes using dielectrophoresis.In the third chapter, the ZnO NW SB UV photodetector with high sensitivity and fast recovery speed has been fabricated and characterized. The ZnO NW makes two SB contacts with the two Au electrodes, and a back-to-back SBs structure is formed. The on/off ratio, sensitivity and gain of photocurrent is 4×105, 2.6×103 A/W, and 8.5×103, respectively. The photocurrent recovery consists of fast and slow processes. In the fast recovery process, the current can decrease exponentially to about 10-3 of photocurrent, and the average recovery time and time constant are 0.28 s and 46 ms, respectively. The photocurrent mechanism of ZnO NW SB photodetector is due to the generation of tunneling current, which is induced by the decrease of Barrier height and increase of electric field near SB interface by trapping photogenerated holes. The dependences of photocurrent on Barrier height and trapped holes are discussed, which indicate that the NW SB photodetector essentially has shorter recovery time than that of NW photodetector.In the fourth chapter we prepared with fast write speed and high-read window resistive switching memory devices. The resistance ratio of off state/on state was 106, write time is <20ns, switching hold time> 104 s. The effects of surface oxygen vacancies on the tunneling barrier height were studied. The pulsed voltage was used to modify the concentration of oxygen vacancies which result in change the SB. In addition, we also analysis the factors on write and erase time, and developed the mechanism of nanowire resistance switch memory.