Single Source Chemical Vapor Deposition Of Heteroepitaxial Growth Of Zno Thin Films

ZnO is a semiconductor material of wurtzite structure with a direct wide-band of 3.37eV and a high exciton binding energy of 60meV at room temperature. It can be used in solar batteries, sound surface wave devices, gas sensors and optoelectronic device due to its outstanding optical and electronic properties. Realizing high quality and the specific orientation ZnO thin films in heteroepitaxial grown is the hot issue in studies, in particular, the controllable growth of ZnO thin films with nonpolar orientation will be studied intensively. The rencent research shows that, nonpolar ZnO has some new characterizations, for example, it can restrain or weaken polarization-induced built-in electric fields caused by spontaneous and piezoelectric polarization in polar ZnO, which can improve Luminous Efficience of ZnO thin films, thought nonpolar ZnO arouses the scientists'attention. ZnO thin films of high crystal quality can be fabricated in heteroepitaxial by changing substrates or adjusting technology parameters. The ZnO thin films of high crystal quality in heteroepitaxial have been prepared by single source chemical vapor deposition (SSCVD) method, the major results as following:1. ZnO thin films with c-axis preferential orientations were deposited on Au/SiO2 substrate using SSCVD method. Effects of substrate temperature on the microstructure of ZnO films have been studied by X-ray diffraction (XRD) and scanning electron microscope (SEM). Finally, the optical properties of ZnO films on Au/SiO2 substrate were determined by PL spectra.2. A-plane orientation ZnO thin films with high crystal quality were grown on Al2O3 (011? 2) substrate by changing substrates and adjusting technology parameters (source temperature,substrate temperature and deposition time). The stress type and size in the a-plane orientation ZnO thin films was calculated through analyzing peak position of (112? 0) diffraction peak, it existed tensile stress in the a-plane orientation ZnO thin films.3. In order to research the heteroepitaxial relation of a-plane orientation ZnO thin films and Al2O3 substrate, theφ-scan spectra of ZnO (101? 1),(101? 0) planes and Al2O3 (202? 2) planes obtained from the same sample were shown. The result indicated that, the out of plane relation was ZnO (112? 0)//Al2O3 (011? 2), and in plane relation was ZnO [1? 101]//Al2O3 [123? 1? ], theφ-scan spectra of ZnO (101? 0) planes revealed the a plane orientation ZnO thin films had high crystallization quality. The reciprocal space mapping of a-plane orientation of ZnO films indicated that it had the strain layer between ZnO thin films and substrate; the strain layer caused crystal orientation difference between ZnO thin films and substrate.4. Photoluminescence (PL) spectrum,Raman scattering and transmission spectrum were employed to analyze the optical properties and the stress in ZnO thin films. The results showed that, PL spectrum indicated the optical properties of ZnO thin films were not satisfactory, which may be attribute to the oxygen vacancies existed in films; Raman scattering spectrum further indicated that the tensile stress existed in the films, which showed with the XRD results, and the tensile stress may be caused by oxygen vacancies; The transmission spectra of a-plane orientation ZnO thin films has been measured in order to detect the absorption edge. In comparison with single crystal ZnO, the band gap became narrower, so it existed tensile stress in the a-plane orientation ZnO thin films, That accorded with XRD and Raman spectrum results. Furthermore, the transmittance of a-plane orientation ZnO thin films reached as high as 85% in the visible range.5. Taking Zn(NO3)2·6H2O as the doping source, N-doping ZnO thin films were made a preliminary exploration. The Hall Effect measurements results showed that the ZnO thin films after N-doping had a stable p-type conduction feature.