Indirect Optical Injection of Carriers and Spin in Silicon*

Degenerate two-photon indirect absorption in silicon is an important limiting effect on the use of silicon structures for all-optical information processing at telecommunication wavelengths. Optical injection of spins in silicon is potentially important for spintronics applications. We theoretically investigate one- and two-photon indirect absorption in silicon, using a pseudopotential description of energy band and the adiabatic bond charge model to describe phonon dispersion and polarization. Spin injection is calculated as well. We compare our results with experiments.