Controllable Growth Different Spacing And Density Of ZnO Nanorod Arrays With Their Photo-electric Properties

ZnO nanorod arrays offer the advantages of enhanced light absorption, improved carrier collectionefficiency, and longer lifetime for minority carriers, which can find many applications from field emissiondevices, sensors, solar cells, nano-generators to UV photo-detectors with the significantly improvedperformances. The photo-electric response and charge carriers transport can be influenced greatly by thedensity and spacing of the patterned ZnO nanorod arrays, which is beneficial to improve performances ofnanodevices. The combination of EBL and hydrothermal growth process was very attractive and made uscould control the geometric parameters of ZnO nanorod arrays expediently. Study the spacing and densityof ZnO nanorods array is very important for ZnO device, it has good application in future. This thesisfocuses mainly on the following aspects:1、ZnO nanorod arrays were prepared on various substrate just as silicon, glass and ITO with Zn seedlayers by magnetron sputtering method followed with hydrothermal reaction process. The morphologies、crystal structure and luminescence properties of ZnO nanorod arrays have been characterized respectivelyby scanning electron microscopy （SEM）, high-resolution TEM （HRTEM）, X-ray diffraction （XRD） andphotoluminescence （PL）. Research results indicated that ZnO nanorods were successfully obtained ondifferent substrates we used in our experiment. HRTEM indicated that high quality and single-crystallinestructure of ZnO nanorods were obtained with growth orientation along the [0001] direction, and onlyintrinsic photoluminescence was observed on the rod arrays.2、Different density and spacing distance ZnO nanorod arrays were fabricated on silicon （Si）substrate by electron beam lithography （EBL） method combined with the subsequent hydrothermal reactionprocess. By using the EBL method, patterned ZnO seed layers with different areas and spacing distanceswere obtained firstly. ZnO nanorod arrays with different density and various morphologies were obtainedby the subsequent hydrothermal growth process. The combination of EBL and hydrothermal growthprocess was very attractive and made us could control the geometric parameters of ZnO nanorod arraysexpediently, By adjusting the temperature and the pH value in the hydrothermal reaction process, the bestparameters for fabrication of ZnO nanorod arrays were obtained: temperature was80℃, pH was10.4. Finally, the vertical transport properties of the patterned ZnO nanorod arrays were investigated through themicro probe station equipment and the I-V measurement results indicated that back-to-back Schottkycontacts with different barriers height were formed in dark conditions. Under UV light illumination, thepatterned ZnO nanorod arrays showed a high UV light sensitivity, and the response ratio was about104.3、ZnO/TiO₂core/shell structure was formed through deposition of a TiO₂coating layer on thepatterned flower like ZnO nanorod arrays by magnetron sputtering method. This heterojunctions displaygood photovoltages characters: the open-circuit voltage （V oc）≈0.18V, and the short-circuit current（I sc）≈7.7nA. The UV light response test showed that enhanced photocurrent with faster response andreset time in the photovoltaic device, indicating improvement in charge separation and collection in thepatterned type II core/shell nanorod arrays.