Papers by Author: Anna Park

Abstract: The structure and electrical properties of ZrO2 dielectric thin films deposited by rf magnetron sputtering were investigated. The fixed oxide charge and interface trap density at the ZrO2/Si interface is substantially decreased by annealing at 500 C. Annealing treatment also enhances the quality of the film by reducing leakage current. The carrier transport mechanism in the ZrO2 film is dominated by thermionic emission.

Abstract: Effects of the O2/Ar flow ratio in the reactive sputtering process and the annealing temperature on the structure and surface roughness of ZrO2 films and the electric properties of Pt/ZrO2/Si MOS capacitors in which the ZrO2 film was deposited by magnetron sputtering have been investigated. The optimum process parameters of the Pt/ZrO2/Si capacitor based on reactively sputtered- ZrO2 determined in such a way as the capacitance is maximized and the leakage current, the oxide charge, and the interface trap density are minimized is the O2/Ar flow ratio of 1.5 and the annealing temperature of 800°C

Abstract: It is very desirable to grow ZnO epitaxial films on Si substrates since Si wafers with a high quality is available and their prices are quite low. Nevertheless, it is not easy to grow ZnO films epitaxially on Si substrates directly because of formation of an amorphous SiO2 layer at the interface of ZnO and Si. A Zn film and an undoped ZnO film were deposited sequentially on an (100) Si substrate by rf magnetron sputtering. The sample was annealed at 700°C in a nitrogen atmosphere. X-ray diffraction (XRD), photoluminescence (PL) and atomic force microscopy (AFM) analyses were performed to investigate the cristallinity and surface morphology of the ZnO film. According to the analysis results the crystallinity of a ZnO thin film deposited by rf magnetron sputtering is substantially improved by using a Zn buffer layer. The highest ZnO film quality is obtained with a 110nm thick Zn buffer layer. The surface roughness of the ZnO thin film increases as the Zn buffer layer thickness increases.

Abstract: This paper investigated the effects of annealing atmosphere on the carrier concentration, carrier mobility, electrical resistivity, and PL characteristics as well as the crystallinity of ZnO films deposited on sapphire substrates by atomic layer deposition (ALD). X-ray diffraction (XRD) and photoluminescence (PL) analyses, and Hall measurement were performed to investigate the crystallinity, optical properties and electrical properties of the ZnO thin films, respectively. According to the XRD analysis results, the crystallinity of the ZnO film annealed in an oxygen atmosphere is better than that of the ZnO film annealed in a nitrogen atmosphere. It was found that annealing undoped ZnO films grown by ALD at a high temperature above 600°C improves the crystallinity and enhances UV emission.