Microluminescence depth profiles and annealing effects in porous silicon

Abstract
Cross‐sectional microluminescence measurements for 1 Ω cm 70 μm porous silicon samples show a continuous decrease of the photoluminescence band as a function of sample depth. No spectral shift is observed. For samples annealed at 390 °C, in addition to spectral intensity reduction, we observe the same redshift in all luminescence spectra independent of depth. A study of this luminescence redshift as a function of annealing temperature reveals a striking similarity to results observed for optical band gap shrinking of a‐Si:H as a function of hydrogen loss during annealing.