Germanium for next generation photonic and microelectronic devices

随着持续的指数增长，到2020年，全球互联网流量预计将达到2.3 ZB(2.3x270)[2016思科]。然而，主流的短距离通信和片上互连一直由金属线主导，金属线速度慢得多，能源效率低，尺寸难以扩展。通过硅(Si)光子学的光互连被广泛认为是克服这一瓶颈的潜在解决方案。锗(Ge)作为硅相容程度最高的半导体材料，一直是硅光子学的基础和使能材料。GE已被广泛用于提供50 Gbps数据速率的光电探测器和调制器[2015 Chen，2016斯里尼瓦桑]。对于硅兼容激光器，Ge可以用作1)InGaAs和AlGaAs等激光材料和Si[2012 Lee，2016B Lin，2016 Liu，2016 Nakao]之间的过渡层，因为它与它们的晶格失配很小，并且易于与Si集成；2)由于带隙工程，Ge是一种激光材料[2010 Liu，2012 C-A]。在微电子方面，Ge已被广泛应用于用于无线通信的SiGe异质结双极晶体管(HBT)。 我们对硅光子学和微电子学中的Ge提出了以下主题。 1.人们非常希望在硅上制备低缺陷密度的Ge薄膜作为III-V过渡层和Si过渡层。纵横比陷阱技术(ART)可以产生高质量的Ge。然而，它需要额外的制造步骤，而且导热性能较差。低温/高温(LT/HT)生长方法在这两个方面都优于ART生长方法。然而，通用电气的质量并不是那么好。砷掺杂已经被证明可以极大地提高Ge的质量[2016 Lee]，而其他掺杂剂的影响还没有研究。为了在硅上生长高质量的Ge薄膜，我们提出用LT/HT法研究掺杂对Ge质量的影响。 2.提出了通过器件建模和模拟来研究Ge-on-Si激光器的潜力和优化。 3.随着HBT衬底中Ge浓度的增加，Si-Ge互扩散问题变得更加突出。我们建议研究PNP型HBT中的互扩散行为，特别是磷和碳的影响，并对这些影响进行建模，以实现更快、更节能的无线通信系统。 这项拟议的研究将使光电子集成电路(OEIC)能够在硅平台上实现，例如单芯片光收发器，它能够在几秒钟内下载电影，而且比目前使用外部激光器的技术便宜得多，也更小。研究成果将有助于光纤通信的更深入渗透、更快的无线通信以及当前信息技术硬件行业的重大进步。我们坚信，拟议中的研究处于研究前沿，将使加拿大作为光通信和信息技术的世界领先者受益匪浅。

With sustained exponential growth, global internet traffic is expected to reach 2.3 zettabytes (2.3x270) by 2020 [2016 Cisco]. However, mainstream short-reach communications and on-chip interconnects have been dominated by metal wires, which are much slower, less energy efficient and hard to scale in size. Optical interconnections via silicon (Si) photonics have been widely recognized as a potential solution to overcome this bottleneck. Germanium (Ge) as the most Si-compatible semiconductor has been the underlying and enabling material for Si photonics. Ge has been widely used in photodetectors and modulators providing a data rate of > 50 Gbps [2015 Chen, 2016 Srinivasan]. For Si-compatible lasers, Ge can be used as 1) transition layers between lasing materials such as InGaAs and AlGaAs and Si [2012 Lee, 2016B Lin, 2016 Liu, 2016 Nakao] due to its small lattice mismatch to them and the ease of integration with Si and 2) a lasing material thanks to bandgap engineering [2010 Liu, 2012 C-A]. On the microelectronics side, Ge has been widely used in SiGe heterojunction bipolar transistors (HBTs) for applications in wireless communications. We propose the following topics on Ge in Si photonics and microelectronics. 1. It is highly desired to have low defect density Ge films on Si to serve as III-V and Si transition layers. Aspect ratio trapping technology (ART) can produce high quality Ge. However, it needs additional fabrication steps and is inferior in thermal conduction. A low/high temperature (LT/HT) growth method is advantageous over ART in these two aspects. However, the Ge quality is not as good. Arsenic doping has been shown to greatly improve Ge quality [2016 Lee], while impacts from other dopants have not studied. We propose to study doping impacts on Ge quality using LT/HT method for high quality Ge film growth on Si. 2. We propose to study the potential and the optimizations of Ge-on-Si lasers by device modeling and simulations. 3. As higher concentration of Ge is used in HBT base layer, Si-Ge interdiffusion is becoming more problematic. We propose to study the interdiffusion behavior in PNP type HBTs, especially the impacts from phosphorus and carbon and the modeling of these impacts for faster and more energy efficient wireless communication systems. The proposed research will enable optoelectronic integrated circuit (OEIC) on Si platforms such as a single-chip optical transceiver, which provides the ability to download movies in seconds and are much cheaper and smaller than the current technology with external lasers. The research outcomes can lead to deeper penetration of optical fiber communications, faster wireless communications and significant advancements in the current information technology hardware industry. We truly believe that the research proposed is at the research frontier and will benefit Canada as a world leader in optical communications and information technology greatly.