Investigation Of Basic Properties Of Cu Doped ZnO Films And Its Homojunction Deveices By MOCVD

ZnO is a new-type wurtzite II-VI group of wide band gap semiconductor materials with direct wide band gap and wurtzite structure. It has a room-temperature band gap of 3.37eV high exciton binding enery at 60meV, which ensure the potential application in the short wavelength optoelectronic devices, such as the blue-violet light emitting diodes (LEDs) and lasers (LDs). To achieve the extensive use of in the field of optoelectronic devices, the n-and p-type ZnO material with good performance must be obtained first. However, there are many difficulties in the preparation of p-ZnO thin films, and therefore influence the application of ZnO thin films. There are many ways to prepare ZnO films, in which, MOCVD method has an incomparable advantage over others. It will also be a significant attempt to use IB group elements, such as Cu, Ag and Au as the acceptor dopant for achieving p-type doped ZnO materials.In this paper, based on this research background and focusing on the ZnO p-type doping, luminescent properties and other issues, we use metal organic chemical vapor deposition (MOCVD) method to prepare Cu-doped ZnO thin films and its homojunction devices。The research was mainly devided into the following two parts:1. MOCVD method was used to prepare undoped and Cu doped ZnO films on C-Al2O3 substrates of. X-ray diffraction (XRD) tests showed that the films exhibited a good c-axis preferred orientation growth. XPS tests showed Cu elements content in the samples were very low, and didn't increase with increasing the temperature of Cu(tmhd)2 source bottle, which means that the solubility of Cu in ZnO is low. Photoluminescence (PL) test was used to analyse the optical properties of undoped and Cu doped ZnO thin films at room and low temperature. Cu incorporation into ZnO resulted in a new blue-violet (BV) light mession peak with strong intensity and a wide range between 2.8 to 3.3 eV. Further testing by temperature dependent PL analysis indicated that the BV emission originated from donor-acceptor pair (DAP) emission between the unknown shallow donor and Cu-related acceptor. The Cu acceptor ionization energy was also calculated.2. MOCVD method was used to prepare Cu doped ZnO homojunction device on n type 6H-SiC substrate. Unintentionally doped ZnO was used as n-type layer. ZnO:Cu/n-ZnO/n-SiC, ZnO:Cu/n-SiC and ZnO/n-SiC structures were prepared. TheⅠ-Ⅴcurves showed that the three structures all have rectifying behavior, wich could indicated that there was band offset between ZnO and SiC. PL spectra showed typical ZnO near band edge emission and deep level emission in ZnO:Cu/n-ZnO/n-SiC structure device. Electroluminescence (EL) spectra showed a new emission peak (at 2.36eV) appeared in ZnO:Cu/n-ZnO/n-SiC structure device, which would be originated from defect levels related recombination in ZnO.