Optical and electrical properties of porous silicon and stain-etched films

Transformation, Green to Orange-Red, of a Porous Silicon Photoluminescent Surface in Solution

“…Electrochemically etched porous silicon wafers have attracted considerable attention due to their room-temperature visible light emission observed as photoluminescence (PL) upon excitation (PLE) with a variety of visible and ultraviolet light sources. − Under the appropriate in situ conditions, PS first displays a green luminescence , which would appear to be excited during the early and intermediate stages of the etching process. The photoinduced green luminescence then transforms to a final orange-red photoluminescence (600−800 nm), although the precursor emission which is excited on the PS surface can be stabilized for extended periods with appropriate solvation. , Here, we evaluate this green to orange-red transformation and its potential correlation with an oxidation cycle involving the silanone-based silicon oxyhydrides. We thus correlate the observations of this transformation under specific experimental conditions with detailed quantum chemical calculations to suggest a source of the luminescent sites.…”

Electrochemical Methoxylation of an HF-Etched Porous Silicon Surface

“…Under the appropriate conditions, PS displays a “green” luminescence during the early and intermediate stages of the etching process. The green luminescence then transforms to a final “orange-red” luminescence (600−800 nm), although it can be stabilized for extended periods with appropriate solvation. − We have recently carried out a detailed quantum chemical study which, coupled with experiment, suggests that plausible sources of the PS green and orange-red photoluminescent emissions are the silanone-based silicon oxyhydrides strongly bound to the PS surface and that the transformation corresponds to an oxidation cycle involving these oxyhydrides. Here, we again use detailed quantum chemistry to examine the derivatization of the PS surface with the goal of enhanced stability, increased quantum yield for light emission, and the consideration of a protocol for sensor applications.…”

“…While the luminescence from PS is thought to occur near its surface, the source of the visible emission is controversial, as the efficiency and wavelength range of the emitted light can be affected by the physical and electronic structure of the surface, the nature of the etching solution, and the nature of the environment into which the etched sample is placed. − The stabilization of PS and the conservation of its luminescence efficiency represent challenges that might be solved through the derivatization of the surface. In fact, the methoxylations of the surfaces of flat silicon crystals are reported to be key factors accounting for long-term stability and low interfacial recombination characteristics in methanol-based photoelectrochemical cells .…”

Thermal Properties of Porous Silicon

“…Blue shift of PL. PL intensity change Youssef 2001 Cooled ethylene glycol Green PL retained Astrova et al 1995 Plastic and glass containment vessels Blue PL due to plastic boxes outgassing Loni et al 1997 Source small Si crystallites, in contrast to bulk silicon. One should note that this observation might be very important for nanoelectronics applications.…”