Injection and detection of ballistic electrical currents in silicon

摘要

Ballistic electrical currents are injected in Si at 80 K by the quantum interference between the indirect one-photon and two-photon absorptions of a pair of phase-locked harmonically related pulses. The average distance that the electrons and holes move (weighted by their respective free-carrier absorption cross sections) is detected using phase-dependent differential transmission techniques that have a sensitivity of ～ 10~7, nanometer spatial, and 100 fs temporal resolutions. The indirect, phonon-assisted injection process is approximately 50 times weaker than in GaAs, and it causes a relative shift in electron and hole profiles that decays in ~100 fs, but it also results in a shift in the center of mass that persists until it is destroyed by diffusion and recombination on longer time scales. Movement of the electrons or holes of at least 0.4 nm is observed and confirms that the current is an injection, not a rectification, current.