An Exploratory Study Of ZnO Thin Films Synthesized By A Chemical Vapor Transport Technique

Recently,ZnO has become an attractive semiconductor material for a wide band-gap (3.37 eV) and a large exciton binding energy(60 meV) at room temperature(RT).It has been regarded as one of the most promising candidates for the next generation of ultraviolet(UV) light-emitting diodes(LEDs) and lasing devices(LDs) operating at high temperatures and in harsh environments.In addition,ZnO materials possess many unique properties for other applications,such as photo detectors,solar cells,acoustic devices,and gas sensors.So it is very significant for preparing high qualities ZnO thin films.In this thesis,ZnO thin films were successfully deposited by a chemical vapor transport(CVT) technique.The morphologies,crystalline qualities and optical characteristics of ZnO thin films prepared by CVT were investigated by scanning electron microscopy(SEM),X-ray diffraction(XRD) and photoluminescence(PL) analytic technology,respectively.The details are as follows:(1) To investigate the influence temperature on the ZnO thin films growth,ZnO were deposited on Si(100) substrates at 400℃,600℃,and 800℃by a CVT technique.The samples were investigated by XRD and SEM.The results show that the growth temperature can efficiently improve the qualities of ZnO,and the best quality of ZnO thin film was Obtained at 600℃.(2) ZnO thin films were deposited on quartz glass,Si(100) and sapphire(001) substrates at 600℃by a CVT technique.The morphologies,crystalline qualities and optical characteristics of the samples were investigated by SEM,XRD and PL analytic technology, respectively.The scanning electron microscopy(SEM) and X-ray diffraction(XRD) measurements showed that the crystalline qualities of ZnO thin films were sensitively dependent on substrates.ZnO thin film deposited on sapphire substrates exhibited the best morphologies,crystalline qualities and optical properties.