甲烷浓度和晶向偏离角对金刚石单晶生长影响的研究

发布时间：2019-01-28 18:15

【摘要】：金刚石具有硬度大、热导率高、热膨胀系数小等优异特性。在国防巩固、工业生产、科学技术等多个领域中都有广泛的应用。一直以来，制备高品质的金刚石是科研人员所关注的焦点问题，近些年金刚石单晶的研究更是备受瞩目，高速率生长高品质的金刚石单晶成为了人们共同追求的目标。本论文采用MPCVD方法，选取3×3mm2的HTHP（100）单晶金刚石为籽晶，进行单晶制备。发现氧气对金刚石单晶生长有明显的影响，对样品进行Raman、PL光谱测试，结果表明氧气可以抑制非金刚石相的生成，提高单晶金刚石的结晶质量，，同时降低了单晶的生长速率。在生长过程中，固定其它生长条件不变，探究甲烷浓度对金刚石单晶生长的影响，随着甲烷浓度的增加，等离子体中分解出的含碳基团增加，生长速率增大。PL测试结果表明通入不同流量的甲烷会影响CVD金刚石中氮的浓度。随着甲烷浓度的增加，外延层厚度的增厚，晶体内N原子逐渐积累，氮含量呈增加的趋势。但当甲烷浓度为10%时，含碳基团增多，单晶生长速率加快，氮的扩散速度相对降低，外延层中氮含量下降。由SEM和金相显微表面观察可知，随甲烷浓度的增大台阶密度增加。但甲烷浓度增加至10%时，N含量降低，晶体内杂质减少，结晶质量有所提升，台阶密度减少。晶向偏离角对高速率高品质金刚石单晶的生长有一定的影响。在生长前，将籽晶表面分别抛光成与籽晶[100]方向成0°、1.72°、2.63°、3.95°偏离角。实验发现，偏离角为3.95°的样品生长速率最快，结晶质量最好，说明偏离角的引入提高了单晶的外延生长速率。加入0.5sccm氮气后，发现偏离角为0°时，生长速率有所提高，但偏离角为3.89°时，生长速率无明显提高。
[Abstract]:Diamond has excellent properties such as high hardness, high thermal conductivity and low coefficient of thermal expansion. In national defense consolidation, industrial production, science and technology and other fields have a wide range of applications. The preparation of high quality diamond has always been the focus of attention of researchers. In recent years, the research of diamond single crystal has attracted much attention, and high rate growth of high quality diamond single crystal has become the common goal of people. In this paper, MPCVD method is used to prepare 3 脳 3mm2 HTHP (100) single crystal diamond as seed crystal. It is found that oxygen has an obvious effect on the growth of diamond single crystal. The Raman,PL spectra of the sample show that oxygen can inhibit the formation of non-diamond phase, improve the crystal quality of single crystal diamond, and decrease the growth rate of single crystal at the same time. The effect of methane concentration on the growth of diamond single crystal was investigated by immobilization of other growth conditions. With the increase of methane concentration, the carbon-containing groups decomposed in plasma increased. The PL results showed that the concentration of nitrogen in CVD diamond was affected by methane flux. With the increase of methane concentration, the thickness of the epitaxial layer increases, the N atom in the crystal gradually accumulates and the nitrogen content increases. However, when the methane concentration is 10, the carbon groups increase, the growth rate of single crystal increases, the diffusion rate of nitrogen decreases, and the nitrogen content in the epitaxial layer decreases. The results of SEM and metallographic observation show that the step density increases with the increase of methane concentration. However, when the concentration of methane increases to 10, the N content decreases, the impurity in the crystal decreases, the crystallization quality improves and the step density decreases. The deviation angle of crystal direction has certain influence on the growth of high speed and high quality diamond single crystal. Before growth, the seed surface was polished into a deviation angle of 0 掳, 1.72 掳, 2.63 掳and 3.95 掳with the direction of seed crystal [100]. It is found that the sample with a deviation angle of 3.95 掳has the fastest growth rate and the best crystallization quality, which indicates that the introduction of deviation angle increases the epitaxial growth rate of single crystal. When 0.5sccm nitrogen was added, it was found that the growth rate increased when the deviation angle was 0 掳, but the growth rate did not increase significantly when the deviation angle was 3.89 掳.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ163;O78

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