Monolithic Infrared Silicon Photonics: The Rise of (Si)GeSn Semiconductors

TL;DR

(Si)GeSn semiconductors are emerging as promising materials for integrated infrared photonics, but face challenges in growth quality, defect control, and device design that must be addressed for scalable applications.

Contribution

This paper reviews recent advancements and identifies key strategies to overcome current limitations in (Si)GeSn semiconductor development for infrared photonics.

Findings

Demonstration of device-quality epi-layers and heterostructures

Identification of growth and defect control challenges

Proposed strategies for material and device optimization

Abstract

(Si)GeSn semiconductors are finally coming of age after a long gestation period. The demonstration of device quality epi-layers and quantum-engineered heterostructures has meant that tunable all-group IV Si-integrated infrared photonics is now a real possibility. Notwithstanding the recent exciting developments in (Si)GeSn materials and devices, this family of semiconductors is still facing serious limitations that need to be addressed to enable reliable and scalable applications. The main outstanding challenges include the difficulty to grow high crystalline quality layers and heterostructures at the desired Sn content and lattice strain, preserve the material integrity during growth and throughout device processing steps, and control doping and defect density. Other challenges are related to the lack of optimized device designs and predictive theoretical models to evaluate and simulate the fundamental properties and performance of (Si)GeSn layers and heterostructures. This Perspective highlights key strategies to circumvent these hurdles and bring this material system to maturity to create far-reaching new opportunities for Si-compatible infrared photodetectors, sensors, and emitters for applications in free-space communication, infrared harvesting, biological and chemical sensing, and thermal imaging.