Enrichment of silicon for a better kilogram
Enrichment of silicon for a better kilogram
复制标题
DOI：
10.1002/pssa.200925148
复制
发表时间：
2010-01-01
影响因子：
2
通讯作者：
Abrosimov, N.
中科院分区：
文献类型：
--
作者：
Becker, P.;Pohl, H. -J.;Abrosimov, N.
目前正在进行一项艰巨的挑战，即用一定数量的硅原子的质量来取代目前对千克的定义。其先决条件是阿伏伽德罗常数N-A，它定义了摩尔中原子的数量，其相对不确定度优于2 × 10（-8）。硅晶体用于该测定，由此产生的困难是测量天然Si的平均摩尔质量。因此，全球范围内的合作已经启动，以生产类似于5公斤的Si-28单晶，其富集因子大于0.99985，并且具有足够的化学纯度，以便其可以用于确定NA，具有上述目标相对测量不确定度。在下文中，报告了所有工艺步骤的开发和首次成功的试验，并描述了用于生产富集度不低于0.9999的高纯Si-28的新设备。所有步骤都由所有合作伙伴必须遵守的技术路线图（TRM 28）定义，所有关键结果都通过校准和认证的方法测量，例如，最终材料的碳含量低于10（15）原子/cm（3），电阻率在400至1000 Ω cm范围内。简要介绍了基于这种高富集和纯化的Si-28以及并行生产的Si-29和Si-30单晶在固态光谱学、自旋电子学、量子计算、高负载超导光学器件的冷却、超晶格结构（SLS）、太赫兹激光器等领域的新应用。0 2010 WILEY-VCH Verlag GmbH & Co. KGaA，魏因海姆
A metrological challenge is currently underway to replace the present definition of the kilogram by the mass of a certain number of silicon atoms. A prerequisite for this is that the Avogadro constant, N-A, which defines the number of atoms in a mole, is determined with a relative uncertainty of better than 2 x 10(-8). Silicon crystals are used for this determination, the difficulty arising thereby is the measurement of the average molar mass of natural Si. Consequently, a worldwide collaboration has been launched to produce similar to 5kg of Si-28 single crystal with an enrichment factor greater than 0.99985 and of sufficient chemical purity so that it can be used to determine NA with the targeted relative measurement uncertainty mentioned above. In the following, the development and first successful tests of all technological steps are reported, and the new equipment for the production of high-purity Si-28 with an enrichment of not less than 0.9999 is described. All steps are defined by a Technical Road Map (TRM28) mandatory for all partners, and all key results are measured by calibrated and certified means, e.g. the C content of the final material is less than 10(15) atoms/cm(3) and the specific resistance is in the range from 400 to 1000 Omega cm. New applications based on this highly enriched and purified Si-28, and on Si-29 and Si-30 monocrystals produced in parallel, are reported briefly in the fields of solid state spectroscopy, spintronics, quantum computing, cooling of highly loaded SYS optics, superlattice structure (SLS), terahertz laser. 0 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim