Silicon LEDs : efficient emission depends on spin

Physicists have demonstrated the ability to produce efficient silicon LEDs by using an original manufacturing method. The device produced is very simple and provides a luminescence which is both strong and controllable at room temperature by a magnetic field.

In a perfect semi-conductor, the return to equilibrium of electrons brought into an excited state ideally takes place through light emission, thus making it possible to manufacture electroluminescent diodes. As for silicon, the archetypal and essential material of the microelectronics industry, this mechanism is prevented by the nature of its band gap: energy is quite simply lost through dissipation, thereby depriving silicon-based electronic circuits of much functionality.

Recently, physicists at the Nanoscience and Nanotechnology Centre C2N (CNRS/Univ. Paris-Sud) and the Laboratory of Solid-state Materials – LPS (CNRS / Univ. Paris-Sud), together with the Optoelectronics group at the University of Cambridge have taken up this challenge and managed to make an all-silicon device emit light.

They have demonstrated the ability to produce efficient silicon LEDs by means of an original manufacturing method based on GILD (Gas Immersion Laser Doping) laser doping. Besides, observation of the electroluminescence mechanism, a dramatic increase of more than 300% in intensity emitted at room temperature was reported when the device was placed in an appropriately oriented magnetic field. This characteristic was made possible due to laser doping, which enables the production of ultra-doped devices with a well-defined planar geometry, which is an essential prerequisite for being able to align the magnetic and electric field in these LEDs and thus overcome classical magnetoresistance effects.

These studies, published in the journal Nature Communication, open up new opportunities and create a new versatile system to produce large-scale quantum spintronics.

Reference
Room temperature magneto-optic effect in silicon light-emitting diodes
F. Chiodi, S.L. Bayliss, L. Barast, D. Débarre, H. Bouchiat, R.H. Friend and A.D. Chepelianskii
Nature Communications (January 2018)
DOI: https://www.nature.com/articles/s41467-017-02804-6
Contact: Francesca Chiodi, Lecturer Université Paris-Sud (francesca.chiodi@c2n.upsaclay.fr)   
Further information
•    Nanoscience and Nanotechnology Centre – C2N (CNRS/Université Paris-Sud) - https://www.c2n.universite-paris-saclay.fr/fr/
•    Laboratory of Solid-state Physics – LPS (CNRS / Univ. Paris-Sud) - www.lps.u-psud.fr/
•    Cavendish Laboratory, University of Cambridge, UK