Papers by Author: Jing Lu

Abstract: Single crystal SiC has been considered as a leading wide band gap semiconductor for its excellent properties even in severe environments. While the outstanding chemical and mechanical inertness also makes it a difficult to process material. In this work, a flexible machining method was proposed to polish 6H-SiC wafers with semi-consolidated diamond tools prepared by sol-gel technology. To confirm the machining mechanism of this newly developed method, free abrasive polishing slurry and fixed abrasive lapping film were also used for comparative experiments. The results indicated that high quality wafer surface with roughness of Ra 0.962 nm was achieved by using semi-consolidated polishing film with diamond grit size of 1 μm. And compared to the other two machining methods, the abrasive in this flexible tool would take a retraction when polishing, leading to a smoother and scratch-free surface of the work piece.

Abstract: In this paper, diamond abrasive SG films were prepared by means of sol-gel technology for polishing single-crystal SiC wafers. The effects of machining parameters on processing quality including pressure, rotating speed and polishing time were investigated, respectively. The results indicated that the surface roughness decreased with increasing polishing time. While for pressure and rotating speed, there were inflections existing. Polishing SiC wafer under optimized machining parameters, an ultra smooth surface with the roughness of 3.7 nm could be achieved using 40 μm diamond grits.

Abstract: The surface roughness and surface morphology of silicon wafers polished by three different polishing methods were analyzed in this paper. A polishing pad was prepared by means of sol-gel technology as semi-fixed abrasive tool. An electroplated polishing pad was chosen as fixed abrasive tool. And a polishing cloth was chosen as free abrasive tool. The results showed that the surface of silicon wafer polished by the sol-gel polishing pad was superior to the other two. It was easy to get mirror effect with few scratches while the free abrasive and fixed abrasive got lots of scratches on 23silicon wafers. The surface roughness of silicon wafer polished by the sol-gel polishing pad reached 1.41nm measured by atomic force microscope (AFM).

Abstract: Diamond-like B-C-N compounds have the excellent potential properties like diamond or cubic boron nitride. In this paper, diamond-like B₂(CN)₃ compound has been studied by first principle calculations. After geometry optimization, hexagonal and monoclinic B₂(CN)₃ models were obtained. According to the band structure and density of state calculated, they are conducting. The relative stability was proved using elastic constants calculated by Born criterion. The monoclinic B₂(CN)₃ is one of hard material with theoretical Vickers hardness 38 GPa.

Abstract: Quasi atomic layer deposition method has been successfully used to coat detonation nanodiamonds with ultrathin silicon film from decomposition of gaseous monosilane. Transmission electron microscopy observation indicates a continuous silicon coating could be obtained on every individual particle of nanodiamonds. The changes in the microstructural property of silicon thin films deposited at the temperatures of 400, 450, 500, 550, and 600 °C have been characterized by Raman spectroscopy, X-ray diffraction and Energy dispersive spectroscopy techniques. The results show the phase transition of as-deposited silicon from a crystalline to an amorphous then to a crystalline phase with the temperature increase.

Abstract: In SiC whisker reinforced Al matrix composite, the interface reaction significantly influences the property of the composite. Si films have been deposited on SiC whiskers by quasi atomic layer deposition from gaseous SiH4 to protect the whiskers from being eroded by Al matrix. The structure and morphology of the coating were characterized by X-ray diffraction and transmission electron microscope. The coating deposited on SiC whiskers is cubic phase polycrystalline silicon and this ultrathin Si film is even and continuous, completely covering every individual SiC whisker. The effect of the Si coating on improving the whisker/matrix interaction was also studied in this work. The interface layer, Si coating, could effectively protect the SiC whisker from erosion caused by Al matrix during the high temperature manufacturing process and improve the adhesion between the SiC whisker and the Al matrix.