Intense wide-band photoluminescence (PL) was observed at room temperature from both SiC thin films grown on silicon substrates by hot-filament chemical vapor deposition and anodized SiC thin films formed by electrochemical anodization in HF-ethanol solution. It was found that prolonged irradiation with ultraviolet light from a He-Cd laser (325nm, 10mW) generally enhanced the PL intensity of as-grown SiC but induced a new PL band in anodized SiC at room temperature. The light-induced PL emission in anodized SiC was centered at the energy between 2.1 and 2.2eV in comparison with the initial peak position of about 1.9eV. These effects were also temperature dependent.

Nanocrystalline cubic silicon carbide (3C-SiC) films embedded in an amorphous SiC matrix were fabricated by the hot-filament chemical-vapor-deposition technique using methane and silane as reactance gases. High-resolution transmission electron micrographs clearly showed that these films contain naoncrystallites, with an average dimension of about 7 nm, embedded within an amorphous matrix: X-ray photoelectron spectroscopy, x-ray diffraction, infrared absorption, and Raman scattering studies revealed the nanocrystallites as having the structure of that of 3C-SiC. In contrast to 3C-SiC, where no photoluminescence could be observed at room temperature, strong visible emission with a peak energy of 2.2 eV could be seen from the nanocrystalline films at room temperature. The presence of nanocrystalline cubic SiC in these films is believed to result in a change in their energy-band structure, compared to that of 3C-SiC, which promotes radiative recombination of electron-hole pairs.

Intense photoluminescence (PL) was observed at room temperature from porous SiC samples prepared in electrochemical anodization from nano-crystalline SiC thin films grown on Si (100) substrates by hot filament chemical vapor deposition. Raman scattering spectroscopy and high-resolution transmission electron microscopy confirmed the nano-crystalline structure of the host films. For the porous samples formed under weaker anodization conditions, it was found that prolonged irradiation with ultraviolet (UV) light from a He-Cd laser (325nm, 10mW) can induce an enhanced new PL band and change the peak energy from 1.9eV to 2.1eV at room temperature. A defect model is suggested to explain the UV light induced PL change in porous SiC.

A novel technique has been developed to lithographically make fine patterns on PZT films. Employing chemical modification in acetylacetone (AcAc), we have obtained an UV photosensitive PZT sol from which the PZT films to be patterned can be prepared. With methanol as solvent and AcAc as chemical modifier, three sols used to compose the PZT coating sol are obtained from Zirconium oxynitrate (ZrO(NO3)2), lead acetate (Pb (CH3COO)2), and tetrabutyl titanate ((C4H9O)4Ti), respectively. By means of UV-vis and FT-IR spectrophotometers we have found that AcAc can associate with Zr, Pb, and Ti ions to form three chelate complexes, the UV absorption peaks of which are located at wavelength 304, 315 and 329 nm, respectively. However, the photosensitive PZT coating sol has UV absorption peak at around 312 nm. Both the chelate complexes in sol and the UV absorption peak can be remained in the gel films. When the photosensitive PZT gel film is irradiated by UV light containing 312 nm wavelength, its solubility in solvents such as alcohol, acetone and so on is reduced remarkably, while the UV absorption peak disappears with the dissociation of the chelate complexes correspondingly. Utilizing the characteristics, a fine pattern can be obtained by irradiation of UV light on the PZT gel film through a pattern mask and dissolving the non-irradiated area in suitable solvent. After annealing at 680

In this paper, our work is reported on heteroepitaxial monocrystalline SiC films deposited on single-crystalline (111) silicon by hot filament chemical vapor deposition (HFCVD) with a gas mixture of methane, silane and hydrogen at a low temperature of 780℃. The surface micrography and thickness of SiC films on Si (111) substrate were analyzed by scanning electron microscopy (SEM). The characteristics and crystallinity of the SiC film were examined by X-ray diffrac tometer (XRD), transmission electron microscopy (TEM) and auger electron spectrum (AES). The peaks of Si (111), SiC (111) and SiC (222) planes were observed on the X-ray diffraction spectrum, but not the peaks of the SiC (200) or SiC (220) planes. The diffraction pattern of TEM also indicates that the SiC films are single-crystalline structure. AES shows that the element ratio of silicon and carbon in the SiC film is 1:1.004. The preparation conditions were as follows: a filament temperature of 2100℃, substrate temperature of 780°C, hydrogen flow rate of 100 sccm, methane concentration of 8.0%, silane concentration of 1.0% and a reaction pressure of 150 Pa.