This thesis investigates the effects of varying the crystallographic orientations of epitaxial ZnO thin films to produce functional ZnO P-N diodes. First, with the atomic layer deposition (ALD), a p-type m-oriented ZnO epitaxial layer is deposited onto an also m-oriented Al2O3 substrate. Then an n-type ZnO layer, mostly textured along the c-axis, is grown atop to form a P-N diode by RF sputtering method. The Hall Effect of the m-ZnO thin film is measured separately at various temperatures and magnetic fields in Quantum Design¡¦s Physical Property Measurement System (PPMS) to determine the nature of the charge carriers. The m-oriented ZnO films are found to be p-type semiconductors, with carrier concentration approximately ~ 1021 1/cm3, which falls in the category of highly-doped degenerate semiconductor. In order to further prove that these films are indeed p-type, naturally n-type c-textured ZnO films are put on the m-films at room temperature by magnetron sputtering to see if the current-voltage (I-V) curves do follow the P-N junction characteristics. In optimizing the c-ZnO film quality and reducing the effects of the junction defects, the gas-mixture ratio between argon and oxygen was varied to compare for the changes in the performance of the resulted materials and devices. X-ray diffraction was used to characterize the crystallographic orientations and the general qualities of the samples by 2£c-£s scan, rocking scan, £p-scan and pole figure measurement. Understanding of the P-N diode is acquired through the analysis of the leakage current and the quantum tunneling phenomena as manifested in the I-V characteristics.

In this study, the reactive rf magnetron sputtering was used to deposit zinc oxide (ZnO) thin films on SiO2/Si substrate at room temperature. The thermal treatment procedure was carried out to improve the luminescence characteristics of ZnO thin films. The physical characteristics of ZnO thin films with different post annealing process were obtained by the analyses of XRD and SEM. The electron spectroscopy for chemical analysis (ESCA) was used to analyze the chemical states of ZnO thin films. In optical properties, the photoluminescence spectrometer was used to measure the photoluminescence characteristics (PL). According to the results of experiments, the chemical states of ZnO thin films were changed after different post annealing. The photoluminescence characteristics were obtained at different wavelength, and the results indicated that they were affected by the chemical states of ZnO thin films. With 900¢J annealing, the strongest green emission and UV emission intensity can be obtained under the air ambient and the oxygen ambient, respectively. The reason was due to the variation of the proportion of oxygen vacancies and O-Zn bond within the ZnO thin films.

By integrating Nanotechnology and MEMS technology, this thesis aims to research a flexural-plate wave (FPW) sensor for testing Immunoglobulin E (IgE) concentration in blood serum, a significant index for the diagnosis of allergies. The traditional methods of blood assay are time-consuming and costly, and its average accuracy of only 60-70 percent. After compare the major four kinds of acoustic sensor, the FPW sensor demonstrates a high accuracy, high sensitivity, low operation frequency, low diagnosis time and low cost. This thesis utilizes a reactive RF sputter system to deposite the piezoelectric ZnO thin film. To obtain the high C-axis orientation (002) characteristic of ZnO membrane, many parameters such as substrate temperature, Ar/O2 ratio and RF power have been adjusted and optimized during the sputtering process. The effects of varied parameters will be investigated and analysis by using SEM or XRD facilities. In this study, we combined the high figure-of-merits ZnO deposition techniques and single-side anisotropic silicon etch process to implement the process integration of FPW device. Finally, this research has demonstrated a 50-60MHz center frequency can be extracted from such silicon-based FPW microsensor.