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Periodic Reporting for period 1 - SiLAS (SiliconLaser)

Reporting period: 2017-01-01 to 2018-12-31

The electronic industry is currently lacking an efficient light emitter enabling chip-to-chip or core-to-core optical communication within a processor chip. The SiLAS project aims to demonstrate efficient light emission from SiGe alloys which are compatible with the electronics industry. The key point is that we study SiGe alloys within a hexagonal crystal phase, which are predicted to feature a direct bandgap, which is a key point for demonstrating efficient light emission. The project will also study approaches for CMOS compatible fabrication. The final objective of the project is to demonstrate a hexagonal SiGe nanolaser.
The primary objective of this project is to provide a pathway for green ICT, in which energy consumption is considerable reduced by replacing copper wiring by optical interconnects which are powered by silicon compatible light emitters. A silicon compatible light source for silicon photonic integrated circuits will not only find applications for optical interconnects, but might also provide a lightsource for silicon photonics. As a final possible application, we like to mention an integrated SiGe lightsource for disposable sensors. When the expensive III/V laser can be replaced by a SiGe lightsource, these sensors might find applications for medical diagnostics, remote sensing and food safety.
Major achievements after 2 years:
• It has been unambiguously determined that hexagonal silicon-germanium (Hex-SiGe) is a direct bandgap semiconductor for Ge-compositions above approximately ~70%.

• We strongly improved the crystal quality of our Hex-SiGe nanowire shells.

• We demonstrated tuning of the direct bandgap emission between 3.5 µm and < 2.0 µm. The experimental results are perfectly in agreement with our theoretical calculations.

• We experimentally obtained substantial evidence for direct bandgap emission.

• We realized room temperature emission of Hex-Ge.

• Preliminary results indicate amplified spontaneous emission in Hex-Ge
This is the first project ever heading towards optical quality hexagonal SiGe. The project intend to first demonstrate direct bandgap SiGe, followed by the demonstration of a hexagonal SiGe nanoLED, an optically pumped SiGe nanolaser and finally an electrically pumped SiGe nanolaser. The long-term objective of this project is to merge the electronics industry based on Si with the telecommunication industry based on III/V compound semiconductors into a new industry, solely based on both cubic and hexagonal SiGe.
Tunability of the emission of Hex-SiGe
Hexagonal SiGe nanowire shells