Our vision is to integrate light-emitting devices, based on hexagonal silicon-germanium (Hex-SiGe), with existing Si electronics and passive Si-photonics circuitry. This establishes a silicon-compatible technology platform, with full opto-electronic functionality. This new technology promises strongly improved performance in computing and sensing, while simultaneously reducing cost by mass production in existing silicon foundries.
Silicon dominates the electronics industry for more than half a century. However, with their standard cubic-diamond crystal structure silicon, germanium and SiGe-alloys are all indirect band gap semiconductors. Their inability to efficiently emit light has adversely shaped the semiconductor industry we know today. It subdivided the industry into an electronics industry based on silicon and a communication industry established on III/V semiconductor light sources. While III-V technology is lacking advanced electronic processing capabilities on-chip, the Si-electronics industry is severely lacking a light source for data transfer and communication. Accordingly, achieving efficient light emission from SiGe has been a holy grail in silicon technology for decades.
The hexagonal crystal polytype SiGe (Hex-SiGe), as pioneered by the project members, recently emerged as a new direct bandgap semiconductor with excellent light emission capabilities as shown in our Nature paper (Nature 580, 205–209 (2020)). Hex-SiGe is therefore the essential brick that was missing in the silicon industry for opto-electronics capabilities. It will provide additional functionality like light generation (light emitting diode, laser), light amplification (semiconductor optical amplifier) and efficient light detection to silicon technology. These opto-electronic functionalities will expand Si-technology with novel possibilities like intra and inter-chip photonics networks. Last but not least, the fabrication of opto-electronic components in high volume silicon foundries will significantly reduce fabrication cost compared to existing solutions based on expensive III-V materials. By doing so, Hex-SiGe technology will be highly disruptive for both the existing electronics and the integrated photonics industry, since it has the potential to seamlessly merge them into a new SiGe-based opto-electronics industry.
