MPCVD法同质外延生长单晶金刚石

摘要

利用微波等离子体化学气相沉积(MPCVD)法在高温高压(HPHT)下制备的单晶片上进行单晶金刚石同质外延生长,研究了甲烷浓度和衬底温度对金刚石生长的影响.利用扫描电子显微镜与激光拉曼光谱仪对生长前后的样品进行表征.结果表明,利用HPHT单晶片上生长时,主要为层状生长和丘状生长模式,丘状生长易出现多晶结构.降低甲烷浓度能够降低丘状生长密度,提高金刚石表面平整度;金刚石生长速率随甲烷浓度、工作气压和衬底温度的增加而提高,但过高的甲烷浓度(72%)和衬底温度(1150℃)会降低金刚石的质量.所生长出的单晶金刚石质量较为理想,衬底与生长层之间过渡比较自然,金刚石结晶度高,缺陷密度小,但随膜层增厚,非晶碳含量有所增加.%Homoepitaxial growth of single crystal diamond on a diamond substrate prepared by the high pressure high temperature method was carried out by microwave plasma chemical vapor deposition and the effects of methane concentration and substrate tem-perature on the quality of the as-grown diamond were investigated. The diamond was characterized by scanning electron microscopy and Raman spectroscopy. Results show that step growth and hillock growth are two main homoepitaxial growth modes, where a polycrystalline structure appears to form easily in the latter case. The surface roughness of the diamond is effectively improved by decreasing the methane concentration because it suppresses hillock growth. The homoepitaxial growth rate increases with increasing methane concentration, pressure and substrate temperature. However, the quality of the diamond is decreased by increasing the methane concentration and substrate temperature above 2% and 1150 ℃, respectively. The content of amorphous carbon increases with growth layer thickness. A diamond with a high crystallinity and low defect concentration is obtained under optimal conditions.