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Posted by Okachinepa on 01/17/2025 @


Courtesy of SynEvol
Credit: Forschungszentrum Julich / Jhonny Tiscareno
Researchers from the Leibniz Institute for High Performance Microelectronics (IHP), the University of Stuttgart, Forschungszentrum Jülich (FZJ), and their French partner CEA-Leti have successfully created the first electrically pumped continuous-wave semiconductor laser composed solely of group IV elements, also known as the "silicon group" in the periodic table.
Germanium-tin and silicon-germanium-tin are stacked in ultrathin layers to create this novel laser. Its remarkable direct growth on a silicon wafer makes it the first laser of its kind, opening the door for further developments in on-chip integrated photonics. The esteemed publication Nature Communications has published the research findings.
The need for more potent, energy-efficient hardware is being driven by the Internet of Things' (IoT) and artificial intelligence's (AI) explosive expansion. With its capacity to transmit large volumes of data with minimal energy loss, optical data transmission is already the technique of choice for distances more than one meter and is showing benefits even for shorter distances.

Courtesy of SynEvol
Credit: Forschungszentrum Julich / Jhonny Tiscareno
This advancement suggests that low-cost photonic integrated circuits (PICs), which provide notable cost reductions and enhanced performance, may be found in future microchips.
Monolithically integrating optically active components on silicon chips has advanced significantly in recent years. Important parts have been developed, such as waveguides, photodetectors, and high-performance modulators. However, the absence of an effective electrically pumped light source that solely uses Group IV semiconductors has long been a problem.
Historically, these light sources have been based on III-V materials, which are costly and challenging to integrate with silicon. By filling that gap, this novel laser can be seamlessly integrated into current silicon production methods and is compatible with traditional CMOS technology for chip manufacture. Thus, it might be considered the "final missing piece" in the toolbox of silicon photonics.
The researchers have shown continuous-wave operation in an electrically pumped Group IV laser on silicon for the first time. This new laser uses a low current injection of only 5 milliamperes (mA) at 2 volts (V), which is equivalent to the energy consumption of a light-emitting diode, in contrast to earlier germanium-tin lasers that depended on high-energy optical pumping.
By reducing power consumption and heat generation through its sophisticated multi-quantum well structure and ring geometry, the laser can operate steadily up to 90 Kelvin (K), or minus 183.15 degrees Celsius (°C).

Courtesy of SynEvol
Credit: Forschungszentrum Julich / Jhonny Tiscareno
It is the first completely "usable" Group IV laser, grown on common silicon wafers similar to those used for silicon transistors, however more refinements are required to lower the lasing threshold even more and enable room-temperature operation. A clear route forward is suggested by the success of previous optically pumped germanium-tin lasers, which have transitioned from cryogenic to room-temperature operation in a matter of years.
Whereas an electrically pumped laser produces light when an electrical current flows through the diode, an optically pumped laser needs an external light source to produce the lasing light. Since electrical power is converted directly into laser light, electrically pumped lasers are typically more energy-efficient.
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