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.

人们对将锗集成到硅基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，或者通过集成基于硅的光电电路来扩展所述技术的应用组合。关于锗。此外，硅上松弛的锗层适合作为 III-V 族材料的虚拟基板，为光伏发电带来额外的好处。用于器件应用的硅上直接生长锗被排除，因为晶格常数的差异导致三维孤岛和产生仅几个单层后就出现了许多晶体缺陷。使用分级缓冲层仍然可以获得器件能力的薄膜质量。生长温度的大幅降低也会产生光滑的锗薄膜，随后必须在更高的温度下进行退火。第一种方法受到缓冲厚度较大的影响，而第二种方法则受到生长后退火期间硅和锗之间开始相互扩散的影响。或者，使用表面活性剂可以抑制生长过程中的孤岛现象。不幸的是，最好的表面活性剂也是硅和锗的掺杂剂，因此生长过程中的掺入最终导致背景掺杂。该项目旨在使用碳δ层作为硅基板上松弛锗薄膜外延的缺陷过滤器。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防止岛状碳的亚单层覆盖相结合。这种方法可以在硅上形成极薄、光滑的松弛锗薄膜，避免潜在的背景掺杂。此外，我们最近的结果表明碳δ层可以阻止锗薄膜中位错的垂直传播。该项目的重点是研究这种效应的基本机制。考虑到粗糙度和缺陷密度，碳δ层的优化数量和距离以及每个δ层中碳的最佳量将导致锗薄膜具有最佳的结构性能。第二个关键方面是碳介导外延生长的锗薄膜的电特性。我们特别关注碳对载流子迁移率和复合过程的影响，这些影响可能会在 pn 结中引起额外的泄漏。作为最终结果，我们希望对碳介导外延生长的弛豫锗薄膜可实现的品质因数和应用潜力进行评估。