Abstract
The dynamics of the infrared photoluminescence (PL) in silicon powder grown by plasma-enhanced chemical-vapor deposition (PECVD) of silane is reported. A nonlinear dependence of PL intensity on laser power of the form I∝ with n as high as 7 has been found, indicating a multistep-multiphoton excitation process. To confirm this hypothesis a very detailed theoretical and experimental analysis has been performed. As a result, the lifetimes of several levels in the excitation chain have been determined, as well as the optical cross section (σ). For the slowest level σ=3× and the lifetime is as long as 400 ms. As the energy of the emitted photon is smaller than that of the excitation photon, a model involving a considerable nonradiative energy relaxation, together with a tunnel effect is proposed.
- Received 13 June 1994
DOI:https://doi.org/10.1103/PhysRevB.50.18124
©1994 American Physical Society