Ingenious techniques are needed to extend group IV photonics from near-infrared to mid-infrared wavelengths. If achieved, the reward could be on-chip CMOS optoelectronic systems for use in spectroscopy, chemical and biological sensing, and free-space communications.

Mid-infrared photonics in silicon and germanium

Photoelectric detectors are the central part of modern photodetection systems with numerous commercial and scientific applications. p-Type semiconductor materials play important roles in optoelectronic devices. Photodetectors based on p-type semiconductor materials have attracted a great deal of attention in recent years because of their unique properties. Here, a comprehensive summary of the recent progress mainly on photodetectors based on inorganic p-type semiconductor materials is presented. Various structures, including photoconductors, phototransistors, homojunctions, heterojunctions, p-i-n junctions, and metal-semiconductor junctions of photodetectors based on inorganic p-type semiconductor materials, are discussed and summarized. Perspectives and an outlook, highlighting the promising future directions of this research field, are also given.

Photoelectric Detectors Based on Inorganic p-Type Semiconductor Materials.

A surface-illuminated photoconductive detector based on Ge0.91Sn0.09 quantum wells with Ge barriers grown on a silicon substrate is demonstrated. Photodetection up to 2.2µm is achieved with a responsivity of 0.1 A/W for 5V bias. The spectral absorption characteristics are analyzed as a function of the GeSn/Ge heterostructure parameters. This work demonstrates that GeSn/Ge heterostructures can be used to developed SOI waveguide integrated photodetectors for short-wave infrared applications.

https://biblio.ugent.be/publication/3159522/file/4398481.pdf

GeSn/Ge heterostructure short-wave infrared photodetectors on silicon

We propose and analyze a strain-balanced GezSn1-z-SixGeySn1-x-y multiple-quantum-well (MQW) laser. By incorporating a proper amount of -Sn into Ge, a direct-bandgap GeSn alloy can be realized to achieve population inversion in the direct conduction band. The introduction of compressive strain into the GeSn QW can effectively modify the valence band structure to reduce the threshold carrier density. We calculate the electronic band structure and the polarization-dependent optical gain of the strained GezSn1-z-SixGeySn1-x-y MQW laser taking into account the effect of the L-conduction bands. We also present our waveguide design for index guidance and calculate the optical confinement factors of various regions. Our calculation indicates that the modal gain can reach the threshold condition and lead to lasing action.

Strain-Balanced ${\rm Ge}_{z}{\rm Sn}_{1-z}\hbox{--}{\rm Si}_{x}{\rm Ge}_{y}{\rm Sn}_{1-x-y}$ Multiple-Quantum-Well Lasers

In this paper, we present a brief history of silicon photonics from the early research papers in the late 1980s and early 1990s, to the potentially revolutionary technology that exists today. Given that other papers in this special issue give detailed reviews of key aspects of the technology, this paper will concentrate on the key technological milestones that were crucial in demonstrating the capability of silicon photonics as both a successful technical platform, as well as indicating the potential for commercial success. The paper encompasses discussion of the key technology areas of passive devices, modulators, detectors, light sources, and system integration. In so doing, the paper will also serve as an introduction to the other papers within this special issue.

/pdf/the-emergence-of-silicon-photonics-as-a-flexible-technology-206app3ej9.pdf

The Emergence of Silicon Photonics as a Flexible Technology Platform

The study of all-group-IV SiGeSn lasers has opened a new avenue to Si-based light sources. SiGeSn heterostructure and quantum well lasers have been successfully demonstrated in the past few years. It has been reported that, for multiple quantum well lasers, the optical confinement factor plays an important role in the net modal gain. In previous studies, adding a cap layer was proposed to increase the optical mode overlap with the active region and thereby improve the optical confinement factor of Fabry-Perot cavity lasers. In this work, SiGeSn/GeSn multiple quantum well (4-well) devices with various cap layer thicknesses, i.e., 0 (no cap), 190, 250, and 290 nm, are grown using a chemical vapor deposition reactor and characterized via optical pumping. While no-cap and thinner-cap devices only show spontaneous emission, the two thicker-cap devices exhibit lasing up to 77 K, with an emission peak at 2440 nm and a threshold of 214 kW/cm2 (250 nm cap device). The clear trend in device performance disclosed in this work provides guidance in device design for electrically injected SiGeSn quantum well lasers.

Investigation of the cap layer for improved GeSn multiple quantum well laser performance.

The aim of this paper is to analyze a single-crystal micro-ring gyroscope. It is found that Si(111) ring is in-plane isotropic but out-of-plane anisotropic, while Si(100) ring is fully anisotropic. Hamiltonian's principle is used to derive the equations of vibration, which is a set of partial differential equations with variable coefficients. The exact solutions for frequencies and mode shapes are found. It is also found that the degeneracy of frequencies for isotropic ring splits for anisotropic ring Then structure design and dynamic analysis of silicon resonant micro-ring gyroscope are presented. The perturbation method of multiple scales is used to find the explicit expression for the relationship between input (angular velocity) and output (nodal displacement of the ring). The effectiveness of phase-locking for enhancing the output signal is proved and quantitatively analyzed.

Single-Crystal Silicon Micro-Ring Gyroscopes-Attitude Sensors

We report on lateral p-i-n GeSn waveguide photodetector on silicon substrates for complementary metal-oxide-semiconductor (CMOS)-compatible mid-infrared silicon photonics.

Germanium-Tin Lateral p-i-n Waveguide Photodetectors for Mid-Infrared Silicon Photonics

The proposed technology employs gold nano particles (AuNPs) to enhance resolution and sensitivity. Sensor was successfully fabricated and characterized. RI sensing performance shows good resolution of 1.19×10-4 RIU and normalized sensitivity of 0.4892 RIU-1.

Guo-En Chang

Papers

Investigation of the cap layer for improved GeSn multiple quantum well laser performance.

Single-Crystal Silicon Micro-Ring Gyroscopes-Attitude Sensors

Germanium-Tin Lateral p-i-n Waveguide Photodetectors for Mid-Infrared Silicon Photonics

Real Time RI Sensing of Optofluidic Based Waveguide Particle Plasmon Resonance Sensor