Light-Emitting Diodes. (Monographs in Electrical and Electronic Engineering.) By A. A. Bergh and P. J. Dean. Pp. viii+591. (Clarendon: Oxford; Oxford University: London, 1976.) £22.

/pdf/light-emitting-diodes-ubzde6g9qc.pdf

Light-emitting diodes

Lasing is experimentally demonstrated in a direct bandgap GeSn alloy, grown directly onto Si(001). The authors observe a clear lasing threshold as well as linewidth narrowing at low temperatures.

/pdf/lasing-in-direct-bandgap-gesn-alloy-grown-on-si-515b98x7i8.pdf

Lasing in direct-bandgap GeSn alloy grown on Si

Silicon photonics research can be dated back to the 1980s. However, the previous decade has witnessed an explosive growth in the field. Silicon photonics is a disruptive technology that is poised to revolutionize a number of application areas, for example, data centers, high-performance computing and sensing. The key driving force behind silicon photonics is the ability to use CMOS-like fabrication resulting in high-volume production at low cost. This is a key enabling factor for bringing photonics to a range of technology areas where the costs of implementation using traditional photonic elements such as those used for the telecommunications industry would be prohibitive. Silicon does however have a number of shortcomings as a photonic material. In its basic form it is not an ideal material in which to produce light sources, optical modulators or photodetectors for example. A wealth of research effort from both academia and industry in recent years has fueled the demonstration of multiple solutions to these and other problems, and as time progresses new approaches are increasingly being conceived. It is clear that silicon photonics has a bright future. However, with a growing number of approaches available, what will the silicon photonic integrated circuit of the future look like? This roadmap on silicon photonics delves into the different technology and application areas of the field giving an insight into the state-of-the-art as well as current and future challenges faced by researchers worldwide. Contributions authored by experts from both industry and academia provide an overview and outlook for the silicon waveguide platform, optical sources, optical modulators, photodetectors, integration approaches, packaging, applications of silicon photonics and approaches required to satisfy applications at mid-infrared wavelengths. Advances in science and technology required to meet challenges faced by the field in each of these areas are also addressed together with predictions of where the field is destined to reach.

https://iopscience.iop.org/article/10.1088/2040-8978/18/7/073003/pdf

Roadmap on silicon photonics

Hybrid silicon lasers based on bonded III–V layers on silicon are currently the best contenders for on-chip lasers for silicon photonics. On-chip silicon light sources are highly desired for use as electrical-to-optical converters in silicon-based photonics. Zhiping Zhou and Bing Yin of Peking University in China and Jurgen Michel of Massachusetts Institute of Technology assess the three main contenders for such light sources: erbium-based light sources, germanium-on-silicon lasers and III-V-based silicon lasers. They consider operating wavelength, pumping conditions, power consumption, thermal stability and fabrication process. The scientists regard the power efficiencies of electrically pumped erbium-based lasers as being too low and the threshold currents of germanium lasers as being too high. They conclude that III–V quantum dot lasers monolithically grown on silicon show the most promise for realizing on-chip lasers.

/pdf/on-chip-light-sources-for-silicon-photonics-ky23qv18q4.pdf

On-chip light sources for silicon photonics

Abstract The emergence of silicon photonics over the past two decades has established silicon as a preferred substrate platform for photonic integration. While most silicon-based photonic components have so far been realized in the near-infrared (near-IR) telecommunication bands, the mid-infrared (mid-IR, 2–20-μm wavelength) band presents a significant growth opportunity for integrated photonics. In this review, we offer our perspective on the burgeoning field of mid-IR integrated photonics on silicon. A comprehensive survey on the state-of-the-art of key photonic devices such as waveguides, light sources, modulators, and detectors is presented. Furthermore, on-chip spectroscopic chemical sensing is quantitatively analyzed as an example of mid-IR photonic system integration based on these basic building blocks, and the constituent component choices are discussed and contrasted in the context of system performance and integration technologies.

/pdf/mid-infrared-integrated-photonics-on-silicon-a-perspective-31psns51w2.pdf

Mid-infrared integrated photonics on silicon: a perspective

Growth Studies of Doped SiGeSn/Strained Ge(Sn) Heterostructures

We report the analysis of the electrical properties of Inx−1GaxP nanowires (NWs) grown by template-assisted selective epitaxy. The individual NW properties are investigated by means of electron beam induced current microscopy (EBIC) and current-voltage curves acquired on single nano-objects. First, a set of samples containing n-doped InGaP NWs grown on a p-doped Si substrate are investigated. The electrical activity of the hetero-junction between the NWs and the substrate is demonstrated and the material parameters are analyzed, namely, the n-doping level is determined in relation to the dopant flow used during the growth. These results were used to design and elaborate InGaP NWs containing a p-n homo-junction. The electrical activity of the homo-junction is evidenced using EBIC mapping on single NWs, and material parameters (namely, the doping and the minority carrier diffusion lengths) for the p- and n-doped InGaP segments are estimated. Finally, the first proof of a photovoltaic effect from the NW homo-junctions is obtained by photocurrent measurements of a contacted NW array under white light irradiation.

/pdf/nanoscale-analysis-of-electrical-junctions-in-ingap-10pxmcfizk.pdf

Nanoscale analysis of electrical junctions in InGaP nanowires grown by template-assisted selective epitaxy

The growth and characterization, including band structure and gain calculations, of strain engineered (Si)GeSn/GeSn heterostructures with large Sn content are presented and discussed in the view of the realization of a direct band gap semiconductor.

Strain engineering for direct bandgap GeSn alloys

The influence of Si-doping on the growth and material characteristics of InAs nanowires deposited by metal-organic vapor phase epitaxy (MOVPE) was investigated. It was observed that above a certain partial pressure ratio, doping has an influence on the morphology. The nanowires exhibit better uniformity but lower height vs. diameter aspect ratio as the supply of the dopant increases. It was consistantly found that the specific conductance of the nanowires also increases. Moreover the electrical measurements showed a transition from semiconducting to metallic behavior in the case of highly doped nanowires.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S1946427400003833

Influence of Silicon Doping on the SA-MOVPE of InAs Nanowires

As we increasingly move beyond conventional silicon CMOS towards more hybrid technology platforms there is a rising interest in integrating other materials on the Si substrate. Co-integrated III-V materials could strongly enhance electronic properties by providing increased electron mobility or tunable heterostructures or add additional functionality for silicon photonics via integrated direct bandgap materials [1], [2]. We have developed a method for monolithic III-V integration on Si, where we grow III-V material within lithographically defined oxide cavities [3]–[7]. This provides us with a high degree of control and versatility, while eliminating some of the constraints associated with either buffer layers or traditional selective area growth of nanowires. As shown in Fig. 1 this method has been employed to demonstrate various electronic devices ranging from high performance InGaAs nFET [7], ballistic transport in nanowires [8] to complementary III-V heterostructure Tunnel FETs (TFETs) where we have demonstrated a scalable platform for complementary TFETs [9], [10]. Recently we have also expanded this technology to optically active devices, enabling monolithically integrated micro-cavity GaAs [11], [12] and InGaAs lasers [13].

Stephan Wirths

Papers

Growth Studies of Doped SiGeSn/Strained Ge(Sn) Heterostructures

Nanoscale analysis of electrical junctions in InGaP nanowires grown by template-assisted selective epitaxy

Strain engineering for direct bandgap GeSn alloys

Influence of Silicon Doping on the SA-MOVPE of InAs Nanowires

Monolithic Integration of III -V on silicon for photonic and electronic applications