Silicon-Photonics Hot-Electron Light Sources

ongoing

The aim of the SPOTLIGHT project is to design, build, measure, and explore a novel class of light sources based on hot-electron emission in silicon bowtie structures. We will pioneer hitherto unexplored light sources that use strongly enhanced light-matter interaction to dramatically increase the radiative decay rate of hot electrons, i.e., electrons injected in high-energy bands. These high-energy bands do not play a role in light sources today because electrons in solids couple so strongly to phonons that they decay rapidly by phonon emission before any appreciable light emission can occur. As a result, even if electrons are injected at energies high up in the conduction bands, they decay non-radiatively to the conduction band edge on a picosecond timescale. This implies that essentially all electronics and photonics today rely on physical processes occurring close to the band gap and this holds for transistors, resistors, lasers, light-emitting diodes, single-photon sources, and much more. My idea builds on a recent breakthrough in my group where we demonstrated a novel type of nanocavity, capable of confining light to optical mode volumes so small that they were considered fundamentally impossible just a few years ago. These unique concepts enable speeding up the radiative processes by orders of magnitude, turning hot electrons in any semiconductor into a bright light source whose wavelength will be determined by the cavity, not the band gap. Our material of choice will be silicon, not only because it is the most important material in micro- and nanoelectronics for which an integrated light source is a long-sought goal, but also because silicon offers the most advanced nanotechnology. This will be crucial for our exploration of this uncharted frontier of semiconductor devices with unprecedented dimensions and unprecedented light-matter interaction strengths where new insights may have profound impact on nanotechnology, photonics, and beyond.