MPCVD法在基片边缘生长大颗粒金刚石的研究

Study on Growth of Large-sized Diamonds at the Substrate Edge by MPCVD

本研究在自制的5 kW大功率MPCVD装置中,利用边缘效应成功的在基片边缘处以50μm/h的沉积速率沉积出晶粒尺寸达500μm左右的大颗粒金刚石并以70μm/h的沉积速率同质外延修复长大了一颗天然的单晶金刚石。在实验中,利用SEM和Ram an光谱对基片边缘区域和中央区域所沉积的金刚石颗粒进行了表征。结果表明,边缘处沉积的金刚石颗粒与中央区域沉积的金刚石颗粒相比,具有更大的晶粒尺寸和更好的质量。通过仔细观察实验条件,对边缘效应产生的原因进行了分析,发现由于基片边缘放电,使得基片表面的电场强度和温度分布发生变化,从而导致基片边缘区域的等离子体密度和温度高于中央区域,高等离子体密度和温度的综合作用是使得在基片边缘能以较高的沉积速率沉积出大尺寸金刚石颗粒的主要原因。

Large-sized diamond crystal with the size of 500 μm was deposited on Si substrate in a home-made microwave plasma assisted CVD reactor（2.45 GHz,5 kW,water-cooled stainless steel chamber） using edge effect,and the deposition speed was 50 μm/h.Meanwhile,a nature diamond with flaw on its surface was used to be homoepitaxial growth at the deposition speed of 70 μm/h.The diamonds deposited on the edge region and the center region of the substrate and the surface morphology of the grown diamond were characterized by scanning electron microscopy（SEM） and micro-Raman spectroscopy.The results show that the diameter and the quality of diamonds deposited on the edge of the substrate is larger and higher than the diamonds deposited on the center of the substrate.The main reason for the edge effect is concluded that the temperature and the electric field intensity on the edge region are higher than the center of region of the substrate after a series of analysis and experiments.