SiC layers were formed by implantation of C+ into silicon at 35keV to fluence of 1×1018cm-2. Thermal annealing was performed at 900℃ for various time intervals from 1h to 8h, and at various temperatures from 700℃ to 1200℃ for 2h in nitrogen ambient. The phase transformation characteristics in these SiC layers were studied using FTIR spectroscopy and a de-convolution scheme of the IR spectra into amorphous SiC and b-SiC components. Further evolution of the relative amount of the various SiC phases upon annealing could be well described by classical nucleation and growth theory using a three-dimensional growth model. The overall enthalpy of the transformation was determined to be 0.18eV/atom. A three-dimensional growth model was suggested according to the XPS experimental results of redistribution of the implanted carbon during annealing.

The electron field emission properties of planar SiC/Si heterostructures with various surface morphology formed by high dose C+ implantation into Si using a metal vapor vacuum arc ion source were investigated. An implant energy of 35keV was used with doses of 8×1017, 1×1018 and 1.2×1018 ions/cm22 with subsequent annealing in Ar at 1200℃ for various times. X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy showed that a thin stoichiometric SiC surface layer is formed and the surface work function is about 4.5eV. Atomic force microscopy indicated that the size and density of the densely distributed small protrusions formed on the surface vary with preparation conditions. Results showed that there is an optimum annealing time for the corresponding implant dose at which a remarkably low turn-on field of about 1V/mm is observed. The density and size of the small protrusions on the surface are believed to be the main factors affecting the field emission properties.

High dose carbon implantation into silicon to form a β-SiC buried layer has been performed by using a metal vapor vacuum arc ion source. The implantation energy and dose are 65 keV and 1=1018 ions cmy2, respectively. Post-implantation thermal annealing was carried out at 1250℃ for various time intervals in Ar ambient. The composition depth profile, chemical state of C and Si atoms, microstructure and optical properties of the samples have been studied using X-ray photoelectron spectroscopy, Fourier transform IR spectroscopy, cross-section transmission electron microscopy and spectroscopic ellipsometry. For the asimplanted sample, the carbon depth profile shows a Gaussian shape-like distribution with a maximum concentration exceeding the stoichiometric ratio. A clear redistribution of the implanted carbon from the Gaussian shape-like distribution to the two sides is observed during annealing. After annealing at 1250℃ for 10h, a stoichiometric SiC buried layer of approximately 150nm is formed. Results show the annealed sample is a multi-layered structure of SiO2 surface layerySi top layerydamaged Si layeryupper interface layeryb-SiC buried layerylower interface layer on Si substrate. The optical constants of theβ-SiC buried layer formed by ion beam synthesis are determined from simulation of the measured ellipsometric spectra (2.3-5.0eV) using an appropriate multi-layered model and the Bruggeman effective medium approximation.

Photoluminescence from β-SiC nanocrystals embedded in SiO2 films at room temperature has been studied. Theβ-SiC nanocrystals were formed by carbon implantation into Si substrate at 35 keV with various dose, followed by postimplantation annealing at 1200℃ for 30min in Ar ambient. Thermal dry-oxidation of the annealed samples at 1050℃ for 3h was performed to formβ-SiC nanocrystals embedded in SiO2 films. The composition and chemical state of C and Si atoms were characterized by non-Rutherford backscattering spectrometry and Fourier transform infrared spectroscopy, respectively. FTIR results show thatβ-SiC nanocrystals were formed in SiO2 films, and the amount ofβ-SiC nanocrystals in SiO2 films increases with increasing of implanted dose. The photoluminescent properties of the samples were measured at room temperature with a Hitachi F4010 fluorescence spectrophotometer using a xenon lamp as an excitation source (300nm). Two distinguishable PLbands located at around 460 and 535nm were observed in all the samples. The PLintensity significantly depends the implanted dose, and there is a critical implanted dose of 2×1017cm-2, at which the PLintensity reaches the largest value.

采用磁过滤真空溅射离子沉积技术，用氩气和氮气共溅射石墨靶，在不同氮气分压下，制备了一组不同氮含量的四配位非晶碳薄膜（ta-C∶N）。用X射线光电子能谱确定ta-C∶N薄膜中的氮含量；研究了氮含量对ta-C薄膜的拉曼光谱和表面形貌的影响。结果表明：不含氮的ta-C薄膜的拉曼光谱是中心在1580cm-1、范围从1200cm-1至2000cm-1的类高斯峰，表面均匀光滑；含氮的ta-C∶N薄膜，其拉曼光谱分裂为1360cm-1的D带和1580cm-1的G带，且D带与G带的最大强度比，以及薄膜的表面粗糙度随氮含量的增加而增大。最后讨论了氮含量对ta-C薄膜的微结构的影响。