Photoluminescence of erbium-doped silicon: Excitation power and temperature dependence

Photoluminescence measurements have been made on float-zone and Czochralski -grown silicon samples which were doped with erbium by ion implantation. Th e characteristic luminescence spectra in the wavelength range between 1.5 a nd 1.6 mu m were observed. Differences in the multiple line structure of th e spectra indicated that the active luminescent centers have different symm etries and atomic structure. The dependence of the photoluminescence intens ity on the laser excitation power and on the temperature was measured. Resu lts are discussed on the basis of a physical model which includes the forma tion of free excitons, the binding of excitons to erbium ions, the excitati on of 4f inner-shell electrons of the erbium ions, and their subsequent dec ay by light emission. To obtain a quantitative agreement between model anal ysis and experimental data the consideration of Auger processes by which er bium-bound excitons and erbium ions in excited state can decay by dissipati ng energy to conduction band electrons appears to be required. From the tem perature dependence two activation energies are derived which are associate d with the exciton binding energies and with an energy transfer process fro m excited erbium ions back to erbium-bound excitons, respectively. A good q uantitative agreement can be obtained for suitable values of the model para meters. The luminescent properties of the samples of the different types of crystalline silicon are remarkably similar. (C) 2000 American Institute of Physics. [S0021-8979(00)00415-1].