Papers by Author: Shuo Hou

Abstract: Fe nano-films deposited on pure Si wafer by metal vapor vacuum arc (MEVVA) ion deposition system were annealed in hydrogen and then treated by ammonia at 750 °C for the catalyzed growth of aligned carbon nanotube (CNT) arrays. Influence of ammonia on the microstructures of Fe nano-films was analyzed by a field emission scanning electron microscopy (FESEM) and image analysis software. The microstructures of the post-processed Fe nano-films were found depending on the processing time of ammonia and the film thickness. Comparing the growth results of CNTs from 10 nm Fe films, we found that when the processing temperature was 750 °C, the optimum processing time of ammonia was about 10 to 12 min for 10 nm Fe films to catalyze the growth of aligned CNT arrays.

Abstract: Keeping deposition temperature and oxygen pressure constant at 300°C and 4.0×10^-2Pa, respectively, deposition of ZnO thin films with c-axis oriented (002) hexagonal wurtzite crystal structure was achieved by pulsed filtered cathodic vacuum arc deposition (PFCVAD) system at various negative substrate bias on Si(100). The surface morphology was characterized using AFM, and crystallographic structure was studied by means of X-ray diffraction. Based on the biaxial strain model, Strain properties of the ZnO films were investigated by calculation from XRD data. The calculated results revealed that the as-deposited ZnO films exhibited only tensile stress and the tensile stress increased with the elevation of the negative substrate bias. Occurrence of the tensile stress is suggested to be the result of relatively high deposition temperature and the improved deposition rate by elevating the negative substrate bias. It provides a potential method to control the intrinsic stress in the ZnO films by modulation of deposition temperature and the negative substrate bias of PFCVAD system.

Abstract: Dry and wet oxidation silica films doped with silicon ions were prepared using metal vapor vacuum arc (MEVVA) ion source implanter. The does of Si ion beams were kept constant at 3×1016 /cm2 and the energy varied from 42KeV to 70KeV. Five photoluminescence (PL) bands at the wavelength of 560nm, 580nm, 620nm, 650nm and 730nm have been observed at room temperature in all samples. The results of XRD showed none of Si nanocrystals were formed in the as-implanted silica films and originations of the PL bands were defects introduced by implantation. The 560nm PL band originated from oxygen surplus defect small peroxy radical (SPR), whereas the PL bands which ranges from the wavelength of 620nm to 730nm were attributed to non bridge oxygen hole center (NBOHC). Elevating implantation energy resulted in intensity increasing of 560nm PL band of dry oxidation samples but had inverse effects on wet oxidation samples. Influence mechanism of implantation energy on the defect photoluminescence was discussed in this article.