Study On The Photodetecting Properties Of One-dimensional ZnO Nanostructures

Since1990s, the researches about ZnO have been focused from the basicperformance to the in-depth application. At room temperature, the band gap of ZnO is3.37eV, and its exciton binding energy reaches60meV, which is higher than theroom-temperature thermal vibration energy of26meV. Therefore, it can generateexciton luminescence and emit laser with a low threshold. ZnO becomes a hotspotmaterial in optoelectronic field.As an ultraviolet (UV) photodetector, ZnO had a relatively high sensitivity.However, the wide band gap of3.37eV limited its application in the blind (SBUV),visible (VIS) and a near infrared (NIR). In this paper, the photoconductivityperformance of one-dimensional ZnO nanostructure was modulated by doping andbuilding heterostructure. Therefore, the photoconductivity of pure ZnO,Zn2SnO4-sheahed ZnO and Cd-doped ZnO one-dimensional nanostructures wereresearched in detail. The main conclusions are as follows:1. Research on the photodetection properties of pure one-dimensional ZnOnanowires: Pure zinc oxide has a large number of oxygen vacancies, which can formsurface states. Then, surface states are effectively modulated by bias voltage andirradiation intensity. As a consequence, the detection range of ZnO nanowire-baseddevice can be extended to blind ultraviolet and infrared.2. Research on the photodetector based on ZnO/Zn2SnO4heterostructurenanowires with a wide spectral response: The photodetector of Zn2SnO4-sheathedZnO II-type heterostructure nanowire is built with ohmic contact. The ZnO/Zn2SnO4interface states are modulated by bias voltage and illumination intensity. As aconsequence, the photogenerated carriers can be effectively separated by II-typeheterostructure interface. The photodetectors, based on Zn2SnO4-sheathed ZnOheterostructure nanowires, have a relatively high sensitivity, stability andrepeatability.3. Research on photodetection properties of Cd-doped ZnO polycrystallinenanorods: Cd-doped ZnO polycrystalline nanorods were synthesized by low-temperature combustion method. The individual nanorod was made intophotodetector and its optical response was modulated by bias voltage andillumination intensity. The device shows highest sensitivity for the illumination ofultraviolet light with wavelength of350nm, and moreover, it also shows obviousresponse in the wavelength range of200to900nm. In addition, the device cansignificantly reduce persistent photoconductivity compared with pure ZnO-basedphotodetector.