Study Of ZnO Thin Film And Its Buffer Layer Grown By Pulsed Laser Deposition

ZnO is a II-VI compound semiconductor with a wide direct band gap of 3 .3eV at room temperature, exciton binding energy of 60meV, and a hexagonal wurtzite structure. Due to their excellent physical and chemical properties, ZnO films have many realized and potential applications such as surface acoustic wave devices, planar optical waveguides, transparent electrodes, ultraviolet photodetectors, piezoelectric devices, varistors, gas sensors, UV/violet/blue-LEDs (light emitting diodes) and -LDs (laser diodes), etc.And they can be integrated with some materials readily. In recent years , the researches and developments of ZnO films have attracted great attention and interest from researchers and the industry.In this thesis, a PLD system was used for preparation of high-quality ZnO thin films on Si(100) substrates. The substrate temperature, the single pulse energy and the repetition rate are three important factors that affect the quality of thin films. The microstructures, crystallinity and the optical properities of ZnO films are respectively investigated by atomic force microscopy(AFM), X-ray diffraction(XRD) and photoluminescence(PL) spectra. We have studied the controlled growth of ZnO films and got the optimized parameter.The ZnO thin films with a buffer layer have been investigated . Among these epitaxial ZnO thin films, ZnO (002) XRD peak FWHM becomes little which means the ZnO thin films with buffer layer get better , and the quality of the film grown at 700℃shows the best structural quality with a (002) XRD peak FWHM of 0 .206. The mechanism how the buffer layers act on the growth of the thin films has been discussed.