掺硼金刚石薄膜的制备与研究

Preparation and study of boron-doped diamond films

采用微波等离子体化学气相沉积技术在单晶硅、钛、钼、铌、钽基体上制备掺硼金刚石薄膜。分别采用X射线衍射仪、扫描电子显微镜、激光拉曼光谱仪、四探针电阻率测试仪研究其物相组成、表面形貌、晶体结晶性和电阻率。硼原子代替碳原子进入金刚石晶格中,产生更多的缺陷形核中心,导致掺硼金刚石薄膜的金刚石晶粒尺寸和电阻率随着掺硼浓度增加而减小。金刚石薄膜和基体间形成碳化物,金刚石在石墨层上形核生长。碳原子在不同基体中的扩散系数不同,导致硅基掺硼金刚石薄膜的晶粒尺寸更小且更加均匀,金属基体上的部分金刚石出现了异常长大的现象。采用该方法制备的掺硼金刚石薄膜的结晶性较好,由于基体热膨胀系数较金刚石大从而导致薄膜内部产生压应力,使得金刚石薄膜的D峰均向高波数偏移。

Boron-doped diamond thin films were deposited on single crystal silicon,titanium,molybdenum,niobium and tantalum substrates by microwave plasma chemical vapor deposition.The phase composition,surface morphology,crystal crystallinity and electrical resistivity were investigated by X-ray diffractometer,scanning electron microscope,laser Raman spectrometer and four-probe resistivity tester.The boron atom replaced the carbon atom into the diamond lattice and produced more defect nucleation centers,which led to the diamond grain size and resistivity of boron-doped diamond films both decreasing as the boron doping concentration increasing.Carbide was formed between the diamond film and the substrate,and the diamond was nucleated on the graphite layer.The diffusion coefficients of carbon atoms in different substrates varied,which contributed to a smaller and more uniform grain size of the silicon-based boron-doped diamond film and the abnormally grown diamonds on parts of the the metal substrates.The boron-doped diamond film prepared by the method had good crystallinity.The thermal expansion coefficient of the matrix was larger than that of the diamond,which caused compressive stress inside the film and made the diamond peak of the diamond film shift to high wavenumbers.