Study on the doping properties of wide band-gap oxide semiconductor films

• Main Authors: Chia-Hsien Tseng, 曾家賢
• Other Authors: Wu-Yih Uen
• Format: Others
• Language: en_US
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/7352v9

碩士 === 中原大學 === 電子工程研究所 === 101 === Ag-doped ZnO (ZnO:Ag) thin film have been fabricated by atmospheric pressure metal-organic chemical vapor deposition (AP-MOCVD). Diethylizinc (DEZn) and water vapor were used as the precursors of Zn and O, respectively, and Ag was as p-type doping source. The p-type conduction was achieved through the following processes. First, a 10-nm-thick Ag film was evaporated on Si(100) substrate by electron beam evaporation. Then, an undoped ZnO thin film of 0.4 m thick was deposited on top, followed by an annealing performed at 550°C in O2 ambient for 40 min. The annealing process would enhance the thermal diffusion behavior of Ag atoms in ZnO lattice, produce enough quantities of AgZn and activate them to result in p-type conductivity of ZnO:Ag film. X-ray diffraction measurements show the dominance of (002) peak for the ZnO:Ag specimen with annealing treatment, demonstrating a polycrystalline film of wurtzite structure with a highly c-axis preferred orientation. Moreover, Hall effect measurements indicated the p-type conductivity of the ZnO:Ag film with the hole concentration of about 1021 cm-3 and mobility of 2.47 . Low temperature photoluminescence spectroscopy conducted at 4.8 K exhibited an emission line at 3.03 eV, typifying the free electron to acceptor (FA) recombination mechanism, and therefore the doping effect of Ag is recognized. Cl-doped Cu2O (Cu2O:Cl) thin film have been fabricated by chemical bath deposition (CBD). The samples in this study were grown on poly copper substrates by chemical bath deposition system. Copper sulfate (CuSO4．5H2O) and Cupric chloride (CuCl2) were used as the source Cu and doping source Cl, respectively. The polycrystalline copper plates (200um thick, 99.96% purity, 2cm × 2cm size ) were used as substrates. The beakers containing the solution were maintained at 100 °C for 1hr in order to obtain the proposed films. About the deposition solution, we controlled various quantities about CuSO4 and CuCl2. Besides, we defined 10M-2 as 1 unit. The solution containend CuSO4 dissolved in 500ml deionized water. The XRD results show that peak at (111) plane is the most prominent peak in the sample. The optical properties of Cu2O films were investigated by low temperature PL measurements. There are two obvious peaks about 1.72eV and 1.88eV on PL spectra. The band at 1.72 eV is produced by the recombination of excitons bound to a double charged oxygen vacancies (VO2+). Beside, the band at 1.34eV is produced by the recombination of bound excitons at copper vacancies (VCu), but in our study no VCu recombination emission, we think it cause by Cu+ rich and fill vacancy. we measure the Cu2O:Cl sample, there are obvious at 1.88eV produce, it may Cl- caused to dopant level emission. Besides, various quantities of CuCl2 being added the 1.88eV emission produce regularity.