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Structural and electrical evaluation of the influence of carbon delta layers for defect reduction on epitaxial growth of thin, relaxed germanium layers on silicon substrates

碳δ层对硅衬底上薄的松弛锗层外延生长缺陷减少影响的结构和电学评估

基本信息

批准号：
389061803
负责人：
Professor Dr. H. Jörg Osten
金额：
--
依托单位：
Institut für Materialien und Bauelemente der Elektronik
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2017
资助国家：
德国
起止时间：
2016-12-31 至 2020-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/389061803?language=en
关键词：
Structural electrical evaluation influence carbon

项目摘要

The interest in the integration of germanium into silicon-based semiconductor technology is driven by the idea to continue the miniaturization in silicon MOS technology by use germanium MOSFETs with enhanced channel mobility or to extend the application portfolio of said technology by the integration of optoelectronic circuits based on germanium. Moreover, relaxed germanium layers on silicon are suited as virtual substrates for III-V materials yielding additional benefits for photovoltaics.Direct growth of germanium on silicon for device applications is ruled out as the difference in lattice constant leads to three-dimensional islanding and generation of numerous crystal defects after only a few monolayers. Device capable film quality can still be obtained using graded buffer layers. A strong reduction of growth temperature also leads to smooth germanium films, which have to be annealed subsequently at higher temperatures. While the first approach suffers from the large buffer thickness, the second is afflicted with the onset of interdiffusion between silicon and germanium during post-growth annealing. Alternatively, the use of surfactants can suppress islanding during growth. Unfortunately, the best surfactants are also dopants for silicon and germanium, thus incorporation during growth ends up with background doping. This project aims at the use of carbon delta-layers as defect filters in the epitaxy of thin relaxed germanium films on silicon substrates. It originates in our recently developed method of carbon-mediated epitaxy, which combines low-temperature growth with an island-preventing submonolayer coverage of carbon. This method enables extremely thin smooth relaxed germanium films on silicon avoiding potential background doping. In addition, our recent results indicate that carbon delta-layers can block the vertical propagation of dislocations in the germanium film. This project focuses on the investigation of the fundamental mechanisms of this effect. An optimized number and distance of carbon delta-layers together with an optimum amount of carbon in each delta-layer will lead to germanium films with the best possible structural properties considering roughness and defect density. A second key aspect is the electrical characterization of germanium films grown by carbon-mediated epitaxy. In particular, we center on the impact of carbon on carrier mobility and recombination processes that could evoke additional leakage in pn-junctions. As final result, an evaluation of the achievable figures of merit and the application potential of relaxed germanium films grown by carbon-mediated epitaxy is aspired.

将锗集成到基于硅的半导体技术中的兴趣是由以下想法驱动的：通过使用具有增强的沟道迁移率的锗MOSFET来继续硅MOS技术的小型化，或者通过集成基于锗的光电电路来扩展所述技术的应用组合。此外，硅上的弛豫锗层适合作为III-V族材料的虚拟衬底，从而为光致发光提供额外的好处。由于晶格常数的差异导致三维岛化，并且仅在几个单层之后就产生大量晶体缺陷，因此排除了在硅上直接生长锗用于器件应用的可能性。使用渐变缓冲层仍然可以获得器件能力膜质量。生长温度的强烈降低也导致平滑的锗膜，其随后必须在更高的温度下退火。虽然第一种方法遭受大的缓冲厚度，第二种方法受到生长后退火期间硅和锗之间的相互扩散的影响。或者，表面活性剂的使用可以抑制生长期间的岛化。不幸的是，最好的表面活性剂也是硅和锗的掺杂剂，因此在生长过程中的掺入以背景掺杂结束。本计画旨在利用碳三角层作为缺陷过滤器，在矽基板上磊晶薄松弛锗薄膜。它起源于我们最近开发的碳介导外延方法，该方法将低温生长与碳的岛状防止亚单层覆盖相结合。该方法能够在硅上形成极薄的平滑弛豫锗膜，避免潜在的背景掺杂。此外，我们最近的研究结果表明，碳δ层可以阻止位错在锗膜中的垂直传播。该项目的重点是调查这种影响的基本机制。考虑到粗糙度和缺陷密度，碳三角层的优化数量和距离以及每个三角层中的最佳碳量将导致锗膜具有最佳可能的结构特性。第二个关键方面是通过碳介导外延生长的锗膜的电特性。特别是，我们集中在载流子迁移率和重组过程中，可能会引起额外的泄漏pn结的碳的影响。作为最终的结果，可实现的品质因数和应用潜力的碳介导外延生长的弛豫锗薄膜的评价是渴望。