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采用化学气相沉积(CVD)技术,以高温高压(HTHP)合成的(100)金刚石和p型(100)Si为衬底制备了硫掺杂和硼-硫共掺杂金刚石薄膜,利用原子力显微镜(AFM)、扫描隧道显微镜(STM)及隧道电流谱(CITS)等手段分析同质和异质外延CVD掺杂金刚石薄膜的结构和性能.结果表明:异质Si衬底上CVD金刚石的形核密度低,薄膜表面比较粗糙,粗糙度达到18.5nm;同质HTHP金刚石衬底上CVD金刚石薄膜晶粒尺寸约为10—50nm,表面平整,表面粗糙度为1.8nm.拉曼测试和电阻测量的结果显示,在HTHP金刚石衬底上制备的金刚石薄膜晶格完整性更好,薄膜中的缺陷浓度及应力比Si衬底上合成的金刚石薄膜中的低,薄膜的导电性能也高于在Si衬底上制备的金刚石薄膜.扫描隧道电流谱(CITS)测试结果显示,Si衬底上制备的金刚石薄膜晶界处及晶界附近的晶粒表面为高电子发射区,而在HTHP金刚石上制备的金刚石薄膜表面电流分布较均匀;电流-电压(I-V)特性表明在Si和HTHP金刚石衬底制备的硫掺杂金刚石薄膜均具有n型导电结构特征.
Sulfur-doped and boron-sulfur co-doped diamond films were prepared by chemical vapor deposition (CVD) technique using (100) diamond and p-type (100) Si synthesized at high temperature and pressure (HTHP) (AFM), scanning tunneling microscope (STM) and tunneling current spectroscopy (CITS) were used to analyze the structure and properties of homogeneous and heteroepitaxial CVD-doped diamond films.The results show that the nucleation density of CVD diamond on heterogeneous Si substrate Low, the surface of the film is rough, the roughness reaches 18.5nm; CVD diamond film on the homogeneous HTHP diamond substrate has a grain size of about 10-50nm, the surface is smooth and the surface roughness is 1.8nm. The results of Raman test and resistance measurement Shows that diamond films prepared on HTHP diamond substrates have better crystal lattice integrity with lower defect concentration and stress in the films than in diamond films synthesized on Si substrates and also have higher conductivity than thin films grown on Si substrates The results of scanning tunneling current spectroscopy (CITS) showed that the surface of the diamond film prepared on the Si substrate and the grain boundary near the grain boundary were high electron-emitting regions, while the diamond prepared on the HTHP diamond Film surface current The current-voltage (I-V) characteristics show that the S-doped diamond films prepared on Si and HTHP diamond substrates all have n-type conductive structure.