Photoluminescence spectra from porous silicon (111) microstructures: Temperature and magnetic-field effects

Visible and near-infrared (IR) photoluminescence emission spectra (0.9–3.0 eV) from p-type porous Si(111) microstructures are reported as a function of temperature and magnetic field. The visible peak located at 1.84 eV at 4 K shifted to ∼1.56 eV at 575 K where it disappeared; the intensity reached a maximum value at ∼150 K. The photoluminescence spectrum showed no measurable shift in the peak position with magnetic field from 0 to 15 T. Strong IR intrinsic band-to-band emission above and below the bulk silicon band gap at ∼1.09 eV at 300 K was observed. This luminescence was found to be enhanced by two orders of magnitude or more over the IR spectrum from an unanodized wafer.