Using Light to Polarize and Detect Electron Spins in Silicon

Area of Science:

• Solid-state physics
• Quantum optics
• Materials science

Background:

• All-optical detection and control of electron spins in silicon is a long-standing challenge.
• Existing methods like transport techniques have limitations in probing spin properties.

Purpose of the Study:

• To directly probe free electron spin properties in bulk silicon using an all-optical approach.
• To determine optical selection rules for phonon-assisted transitions in silicon.
• To measure electron spin relaxation and exciton spin properties under novel conditions.

Main Methods:

• Circularly polarized light excitation of bulk silicon.
• Measurement of luminescence polarization.
• Experiments covering both direct and indirect band gap excitation.

Main Results:

• Successful all-optical probing of electron spin polarization in silicon.
• Experimental determination of optical selection rules for phonon-assisted transitions.
• Measurement of electron spin relaxation times in previously inaccessible regimes.
• Characterization of free exciton spin properties in silicon.

Conclusions:

• All-optical methods provide a powerful tool for investigating electron spin dynamics in silicon.
• This work overcomes limitations of transport techniques for spin property measurements.
• The study opens new avenues for exploring exciton spin physics in silicon.