M1 INTERNSHIP : Towards electrical control of photon emission from optically active defects in silicon

Le stage se déroulera dans le laboratoire INL (Institut des Nanotechnologies de Lyon) sur le campus de La Doua, dont l'INSA de Lyon est l'une des tutelles.

IMPORTANT : this offer is for a M1 level internship, not M2. The provisional dates are therefore between May and July 2025.

Over the last few decades, the silicon material platform has come to dominate the microelectronics industry, forming the basis for information processing and telecommunications technologies. In the aim to increase data security and transmission rates, whilst reducing the energy needed per bit of information transferred, optical communication systems are being increasingly explored. Naturally, efforts are being made to transpose the technological processes refined for silicon for electronics applications and make them applicable for a future generation of all-silicon photonic devices.

In order to overcome the constraint of silicon’s indirect bandgap and to increase the efficiency of light absorption and emission processes, Silicon Emission Centers (SECs) are being explored as single photon emitting candidates. SECs are local modifications of the crystalline lattice of bulk silicon, in the form of interstitial or substitutional atoms, that can emit light in or close to the near-infrared telecom wavelength bands.

Efficient emission of photons from silicon and their coupling into optical components relies on (i) clearing the silicon of residual charges that may inhibit the radiative emission processes of SECs, and (ii) tuning the emission wavelength of the SECs to the designed operation wavelength of the photonic circuit. Both of these goals may be achieved by imposing an electric field across the spatial region containing the SECs in order to (i) evacuate accumulated charge, and (ii) employ the well-known Stark effect to modify the electronic bands of the SECs. To achieve these goals, ongoing efforts are being made at INL to locally dope thin films of silicon containing SECs, so as to position the latter inside the space-charge region of a p-n junction, that may be polarized by the application of an external bias voltage.

The intern’s work will consist of:

- Refining the doping protocol of a silicon thin film so as to create a p-n junction featuring a space-charge region with appropriate dopant concentrations with sub-micron lateral positioning around single or multiple SEC sites. The junction will be created using an innovative, implantation-free process mastered at INL, involving the thermal diffusion of dopants applied onto the surface of the sample by spin-coating. This work will be carried out in a cleanroom environment and will require successive technological steps : selective masking around the region to be doped, thermal diffusion of dopants into silicon, characterization of the dopant profile obtained using the ECV (electro capacitance voltage) technique. The intern may also participate in the simulation of the electrical structures envisaged in order to determine optimal dimensions and dopant concentrations.

- Positioning of metallic contacts on the surface of the aforementioned samples to allow for polarization of the junction under external bias.

- Assisting with low temperature photoluminescence measurements seeking to characterize the response of the SECs’ emission properties (principal wavelength, Debye-Waller factor…) to the application of an external bias voltage. 

The internship student will receive a monthly gratification of 633 euros if the duration exceeds 8 weeks.

Etudiant inscrit en master (niveau M1).