摘要
金刚石具有最宽的禁带宽度、高载流子迁移率、最高的热导率、良好的化学惰性和优异的抗辐射性能。因此金刚石器件极具应用潜力,但合成金刚石条件苛刻、难以加工并且成本高昂,要使得金刚石器件进一步应用,甚至取代硅器件必须降低生产成本,提高金刚石的生长质量。本文采用6 kW圆柱形谐振腔式微波等离子体化学气相沉积(MPCVD)设备,在输入功率、气体压力和生长温度等工艺条件不变的情况下,考察自行设计的样品台几何结构(圆柱形样品台和梯形样品台)对同质外延单晶金刚石生长的影响;基于此,在梯形样品台上,探索了不同甲烷浓度对外延单晶金刚石的生长特征影响。利用等离子体发射光谱(OES)诊断分析等离子体放电环境的特征,同时通过激光拉曼光谱(Raman)、X射线衍射(XRD)、光学显微镜(OM)和原子力显微镜(AFM)的测试手段对外延金刚石的表面形貌和晶体质量进行分析。结果表明:在3%的甲烷浓度下,平面圆柱样品台生长的金刚石生长速率为4μm·h^(-1),表面形貌光滑,拉曼半峰宽为3.6 cm^(-1),晶体质量较高;梯形样品台生长的金刚石生长速率为1.8μm·h^(-1),表面出现较多刻蚀坑,形貌较粗糙,拉曼半峰宽为4.5 cm^(-1),晶体质量较差。此外,在梯形样品台上,增加甲烷浓度至5%时,金刚石的生长速率提高至3.8μm·h^(-1),表面形貌较光滑,刻蚀坑消失,拉曼半峰宽为3.7 cm^(-1),金刚石质量明显改善。以上结果证实样品台几何结构可以对金刚石生长的等离子体环境产生影响,进而影响同质外延金刚石的生长质量。
Diamond has the widest band gap,high carrier mobility,highest thermal conductivity,good chemical inertness,and excellent radiation resistance.Therefore,diamond devices have great application potential,but synthetic diamond has harsh conditions,is difficult to process and expensive.To make diamond devices be further used,or to replace silicon devices,it is necessary to reduce production costs and improve the growth quality of diamond.In this article,the effect of geometric structure of a self-made substrate holder(cylindrical and trapezoidal shape)on the growth of a homoepitaxial single-crystal diamond was investigated using the 6kW cylinder-type resonator microwave plasma chemical vapor deposition(MPCVD)equipment,while keeping the same experimental conditions such as microwave power,chamber pressure,and deposition temperature.On this basis,the homoepitaxial single-crystal diamond was also deposited on the trapezoid-shaped substrate holder when the different methane concentration was used.The characteristics of the plasma discharge were diagnosed during the diamond deposition via plasma optical emission spectroscopy(OES),and the surface morphology and crystal quality of homoepitaxial single-crystal diamond were characterized by laser Raman spectroscopy(Raman),X-ray diffraction(XRD),optical microscope(OM)and atomic force microscope(AFM).The results suggested that when the methane concentration was set to be 3%,the single-crystal diamond grown on the cylinder-shaped substrate exhibited smooth morphology with a growth rate of about 4μm·h^(-1) and the Raman FWHM of 3.6 cm^(-1),indicating high crystal quality.However,the diamond deposited on the trapezoid-shaped substrate is rough and has some etched pits,along with a low growth rate of about 1.8 μm·h^(-1) and a large Raman FWHM of 4.5 cm^(-1).Furthermore,the growth rate of diamond on the trapezoid-shaped substrate holder reached 3.8 μm·h^(-1) when increasing the methane concentration to 5%.The resulting single-crystal diamond exhibited a smooth surface and the etched holes had disappeared.Its Raman FWHM became narrower,only about 3.7 cm^(-1).These results strongly suggested that the geometric structure of the substrate holder had obvious influence on the plasma environment for the deposition of diamond,and further affected the quality of the homoepitaxial single-crystal diamond,which in turn affects the growth rate,crystal morphology and crystal quality of homoepitaxial single crystal diamond.By optimizing the geometrics structure of the substrate holder,the growth rate,surface morphology,and crystal quality of single crystal diamond grown by MPCVD method could be improved.
作者
王国欣
熊鹰
王兵
陈卓
杨森
Wang Guoxin;Xiong Ying;Wang Bing;Chen Zhuo;Yang Sen(School of Material Science and Engineering,Southwest University of Science and Technology,Mianyang 621010,China;State Key Laboratory for EnvironmentalFriendly Energy Materials,Mianyang 621010,China)
出处
《稀有金属》
EI
CAS
CSCD
北大核心
2021年第9期1095-1102,共8页
Chinese Journal of Rare Metals
基金
国家自然科学基金项目(51572229)
四川省科技计划重点研发项目(2019YFG0065)资助。
关键词
同质外延
金刚石
样品台结构
微波功率密度
甲烷浓度
homoepitaxy
single-crystal diamond
geometricstructure of substrate holder
microwave power density
methane concentration
