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金刚石具有一系列优于其他材料的极限特性, 应用领域十分广泛. 金刚石大单晶更能充分发挥其功能特性, 从而成为国内外研究的热点. 为此, 本文在介绍金刚石大单晶高温高压合成原理及工艺技术的基础上, 重点综述了四种类型的金刚石大单晶以及掺杂金刚石大单晶的研究现状和研究重点. Ia型金刚石大单晶可由Ib型金刚石通过高温高压退火处理得到, 其中氮的转变机制及效率研究十分重要; 对Ib型金刚石大单晶的表面分析表征、晶体缺陷控制、再结晶石墨析出、多晶种法批量化生产方面进行了综述; 对IIa型金刚石大单晶中除氮剂和触媒的选择、微晶石墨析出与抑制方面的研究进行了介绍; 研究了IIb型金刚石中硼元素的扇区存在及其对合成金刚石生长特性的影响; 掺杂金刚石大单晶主要从B, N, S, P等不同掺杂元素的不同掺杂源或与硼等协同掺杂的研究状况进行了介绍. 并提出金刚石大单晶需要在Ib及IIa型的批量化、IIb型的超导特性、掺杂n型半导体方面加强研究.Diamond has a series of extreme characteristics superior to other materials, and also very wide application scope. The large diamond single crystal can play a role in its functional characteristics, which has become a research hotspot. In this paper, we introduce the principle and process of synthesizing large diamond single crystal by temperature gradient method (TGM) under high pressure and high temperature (HPHT), and summarizes the research status and research directions of different types of and additives-doped large diamond single crystals respectively. The principle of the temperature gradient method is that the carbon source, driven by the temperature gradient, diffuses from the high concentration region at the high temperature end to the low concentration region at the low temperature end, and diamonds are grown on the seed crystal. The growth rate of diamond crystal is controlled by adjusting the axial temperature gradient at synthesis cell, and the shape growth of Ib-type large diamond is controlled by the distribution in the V-shaped growth area. We introduce different kinds of diamond large single crystals from five aspects. Firstly, the Ia-type diamond large single crystal can be obtained by the annealing treatment of Ib-type diamond under HPHT. The conversion rate of C centre to A centre for nitrogen in diamond is improved by optimizing the conditions of HPHT. Secondly, the Ib-type larger diamond is studied very much in the following areas: the analysis of its surface characteristic, the control of inclusions and cracks, the precipitation mechanism and the elimination measures of regrown graphite and the mass production technology of multiseed method. Thirdly, IIa-type large diamond single crystal is introduced in which the nitrogen getter is selected due to the ability Al and Ti (Cu) to getter nitrogen, the catalyst is selected because of its effect on the nitrogen content in the diamond synthesized with Fe or Ni based catalyst, and the elimination method of microcrystalline graphite precipitation is presented by analyzing its mechanism. Fourthly, the boron elements exist in IIb-type diamond and have influence on the growth characteristics of synthetic diamond. Fifthly, introduced is the research status of diamond synthesized with B, N, S, P doping elements, in which its individual substance or their compound is used as a doping source or boron and other elements with small radius are used as co-doping agent. Then S or P with B co-doping is more conducive to the improvement of the performance of n-type diamond large single crystal semiconductor. Therefore, it is proposed that the large diamond single crystal need strengthening in mass production of IIa-type large diamond single crystal, superconducting characteristics of IIb-type large diamond single crystal, and doping of n-type semiconductors.
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Keywords:
- high pressure and high temperature/
- temperature gradient method/
- large diamond single crystal
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合金触媒 除氮剂 除氮效果 晶体质量 FeNiCo Ti[59] 氮含量明显减少, 除氮效果好, 很难得到优质IIa型金刚石 金刚石晶体中存在夹杂物和表面蚀坑 Ti/Cu[15] 氮含量小于1 ppm, 除氮效果好 优质IIa型金刚石 NiMnCo Al[58] Al和N存在可逆反应, 除氮效果不好, 很难得到IIa型金刚石 金刚石晶体中存在夹杂物和表面蚀坑 Ti/Cu[15] 氮含量小于1 ppm, 除氮效果好 优质IIa型金刚石 FeCo Ti[61] 氮含量明显减少, 除氮效果好, 很难得到优质IIa型金刚石 表面出现夹杂物 Zr[61] 氮含量明显减少除氮效果好 需要严格控制其生长速度 -
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