Tang K, Kim H S, Ramanayaka A N R, Simons D S, Pomeroy J M
Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20740, USA.
National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8423, USA.
Rev Sci Instrum. 2019 Aug;90(8):083308. doi: 10.1063/1.5097937.
An ultrahigh vacuum (UHV) compatible Penning ion source for growing pure, highly enriched Si epitaxial thin films is presented. Enriched Si is a critical material for quantum information due to the elimination of nuclear spins. In some cases, the material must be grown by low temperature molecular beam epitaxy, e.g., scanning tunneling microscopy hydrogen lithography-based devices. Traditional high-purity physical vapor methods typically deliver a very small fraction of source material onto the target substrate, making the cost for use with highly enriched source materials very high. Thus, directed beam sources provide an efficient alternative. This UHV Penning source uses all metal or ceramic parts and a removable electromagnet to allow bake-out. The source gas is a commercial (natural isotope abundance) silane gas (SiH), an inexpensive source material. High enrichment levels up to 99.999 87% (8.32 × 10 mol/mol Si) and high chemical purity of 99.965% are shown without postprocessing. We present and discuss the discharge properties of this new source, the ion mass spectrum when coupled to our mass filter, and the secondary ion mass spectroscopy of the grown films.
本文介绍了一种用于生长纯净、高富集硅外延薄膜的超高真空（UHV）兼容潘宁离子源。由于消除了核自旋，富集硅是量子信息的关键材料。在某些情况下，该材料必须通过低温分子束外延生长，例如基于扫描隧道显微镜氢光刻的器件。传统的高纯度物理气相方法通常只能将极少量的源材料输送到目标衬底上，这使得使用高富集源材料的成本非常高。因此，定向束源提供了一种有效的替代方案。这种超高真空泵宁源使用全金属或陶瓷部件以及一个可拆卸的电磁铁，以便进行烘烤除气。源气体是一种商业（天然同位素丰度）硅烷气体（SiH），是一种廉价的源材料。在无需后处理的情况下，展示了高达99.999 87%（8.32×10摩尔/摩尔硅）的高富集水平和99.965%的高化学纯度。我们展示并讨论了这种新源的放电特性、与我们的质量过滤器耦合时的离子质谱以及生长薄膜的二次离子质谱。
