Silicon-Based Light Emitting Devices

Silicon’s prominence in microelectronics contrasts with its weak light emission owing to an indirect bandgap that favours non-radiative recombination. Over the past decade, researchers have pursued diverse strategies to overcome this limitation, including impurity doping, nanostructuring and integration of optical resonators. Doping with rare-earth or transition-metal ions introduces radiative centres, while nanoscale cavities and resonators enhance emission via the Purcell effect. Avalanche electroluminescence in reverse-biased p–n junctions yields broad-spectrum infrared output, and whispering gallery mode resonators produce narrowband, polarised lines. Crucially, all approaches strive for compatibility with standard complementary metal-oxide-semiconductor (CMOS) processes to enable on-chip photonic interconnects, lab-on-a-chip sensors, quantum light sources and integrated microscopes, promising to bridge the electronic–photonic divide within a single silicon platform.

Research from Nature Portfolio

Recent studies have demonstrated a sub-wavelength silicon light-emitting diode fabricated on a CMOS platform with an emission area below 0.14 µm² and peak output around 1100 nm, achieving spatial coherence sufficient for lensless in-line holographic microscopy. Investigations of copper-doped silicon in high-Q photonic crystal nanocavities have accelerated spontaneous emission rates by a factor of thirty through strong Purcell enhancement. Work on erbium-oxygen codoping in silicon-on-insulator structures has yielded a forty-fold increase in 1.54 µm luminescence, offering a realistic route to efficient infrared emitters for optical communications and sensing in integrated photonic circuits.

Research from all publishers

A monolithic optical link in silicon-on-insulator technology combined a vertically coupled silicon LED and photodiode separated by shallow trench isolation, exploring both forward and avalanche modes; integrated heat sinks reduced thermal crosstalk, enabling wide-spectrum on-chip data transmission. Micro optical sensors built around avalanching silicon LEDs have been developed for label-free biochemical detection, exploiting high photon flux and sub-micrometre coherence for enhanced sensitivity. All-silicon electrically driven light sources using inversely tapered photonic resonators have realised whispering gallery modes at room temperature, producing narrow linewidths (down to 0.33 nm) and strong polarisation in a footprint of about 1 µm, demonstrating low-voltage, high-spectral-power density operation suitable for dense photonic integration.

Silicon-Based Light Emitting Devices publication trend

The graph below shows the total number of articles in silicon-based light emitting devices across all publications each year (not limited to Nature Index journals).

Technical terms

Indirect bandgap: A semiconductor band structure where conduction-band minima and valence-band maxima occur at different crystal momenta, reducing radiative recombination efficiency.

Purcell effect: Enhancement of an emitter’s spontaneous emission rate when placed inside an optical cavity, proportional to the cavity’s quality factor divided by its mode volume.

Avalanche electroluminescence: Light emission generated by carrier multiplication in a reverse-biased p–n junction under high electric field.

Whispering gallery modes (WGMs): Optical resonances confined by continuous total internal reflection along curved interfaces, characterised by high quality factors and low mode volumes.

Complementary metal-oxide-semiconductor (CMOS): A standard microfabrication technology for integrated circuits, offering process compatibility for monolithic electronic and photonic devices.

References

1. A sub-wavelength Si LED integrated in a CMOS platform. Nature Communications (2023).
2. Micro optical sensors based on avalanching silicon light-emitting devices monolithically integrated on chips. Optical Materials Express (2019).
3. Monolithic optical link in silicon-on-insulator CMOS technology.. Optics Express (2017).
4. Ultrafast spontaneous emission of copper-doped silicon enhanced by an optical nanocavity. Scientific Reports (2014).
5. Super-enhancement of 1.54 μm emission from erbium codoped with oxygen in silicon-on-insulator. Scientific Reports (2016).
6. All-silicon polarized light source based on electrically excited whispering gallery modes in inversely tapered photonic resonators. APL Materials (2020).