Sunday, December 22, 2024

The Last Missing Piece of Silicon Photonics

Good news! This could be a breakthrough!

"International research team presents first electrically pumped continuous-wave semiconductor laser suitable for seamless silicon integration

Scientists from Forschungszentrum Jülich, FZJ, the University of Stuttgart, and the Leibniz Institute for High Performance Microelectronics (IHP), together with their French partner CEA-Leti, have developed the first electrically pumped continuous-wave semiconductor laser composed exclusively of elements from the fourth group of the periodic table – the “silicon group”. Built from stacked ultrathin layers of silicon germanium-tin and germanium-tin, this new laser is the first of its kind directly grown on a silicon wafer, opening up new possibilities for on-chip integrated photonics. ...

Key components, including high-performance modulators, photodetectors, and waveguides have been developed. However, a long-standing challenge has been the lack of an efficient, electrically pumped light source using only Group IV semiconductors. Until now, such light sources have traditionally relied on III-V materials, which are difficult and therefore expensive to integrate with silicon. ...

For the first time, the researchers have demonstrated continuous-wave operation in an electrically pumped Group IV laser on silicon. Unlike previous germanium-tin lasers that relied on high-energy optical pumping, this new laser operates with a low current injection of just 5 milliamperes (mA) at 2 volts (V), comparable to the energy consumption of a light-emitting diode. With its advanced multi-quantum well structure and ring geometry, the laser minimizes the power consumption and the heat generation, enabling stable operation up to 90 Kelvin (K) or minus 183.15 degrees Celsius (°C). ...

further optimizations are needed to further reduce the lasing threshold and achieve room-temperature operation. However, the success of earlier optically pumped germanium-tin lasers, which have evolved from cryogenic to room-temperature operation in only few years, suggests a clear path forward. ..."

From the abstract:
"Over the last 30 years, group-IV semiconductors have been intensely investigated in the quest for a fundamental direct bandgap semiconductor that could yield the last missing piece of the Si Photonics toolbox: a continuous-wave Si-based laser. Along this path, it has been demonstrated that the electronic band structure of the GeSn/SiGeSn heterostructures can be tuned into a direct bandgap quantum structure providing optical gain for lasing. In this paper, we present a versatile electrically pumped, continuous-wave laser emitting at a near-infrared wavelength of 2.32 µm with a low threshold current of 4 mA. It is based on a 6-periods SiGeSn/GeSn multiple quantum-well heterostructure. Operation of the micro-disk laser at liquid nitrogen temperature is possible by changing to pulsed operation and reducing the heat load. The demonstration of a continuous-wave, electrically pumped, all-group-IV laser is a major breakthrough towards a complete group-IV photonics technology platform."


Credits: Neuer Halbleiterlaser löst zentrales Problem der Silizium-Photonik "Erster elektrisch gepumpter Laser für Siliziumchips entwickelt: Neue Lichtquelle aus Silizium-Germanium-Zinn optimiert die On-Chip-Photonik."


Fig. 1: SiGeSn/GeSn multi-quantum-well structure.



Scanning electron micrograph


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