Luminescence degradation in porous silicon

Abstract

We have studied the stability of the luminescence from porous Si in the presence of a variety of ambient gases (e.g., N2, H2, forming gas, and O2). Although the optical properties are fairly stable under most conditions, illumination in the presence of O2 causes a substantial decrease in luminescence efficiency. Infrared measurements show that the surfaces of degraded samples are oxidized. The luminescence lifetime of the degraded material is found to be substantially reduced, and the density of Si dangling bonds increases by more than two orders of magnitude, which suggests that oxidation of the surface introduces nonradiative recombination channels. These observations indicate that the electronic properties at the surface of the porous Si play a key role in obtaining efficient luminescence from this material.

Unusual Photoluminescence Decay of Porous Silicon Prepared by Rapid Thermal Oxidation and Quenching in Liquid Nitrogen

“…Although we could not follow the decay more exactly, the fast-decay is qualitatively in accord with the decay of the blue luminescence of the PS reported in the literatures. 11,17) In contrast to the unquenched RTO sample, the decay of the RTOQN sample is quite slow (>1 s). To the best of our knowledge, such a slow-decay photoluminescence has not been reported in the past.…”

UV (hν=8.43 eV) photoelectron spectroscopy of porous silicon near Fermi level

“…Also UV illumination with an energy exeeding 3 eV may cause hydrogen loss from porous Si in a nonoxidizing ambient [15]. In addition thermally and optically induced oxidation is known to rapidly degrade the photoluminescence intensity [16]. This coinsides with re-sults of electron paramagnetic resonance measurements [17] showing formation of disordered dangling bond centers in porous Si annealed thermally in oxygen at temperatures between 420÷770 K. We can assign the red luminescence with process es induced by diffusion of photogenerated electrons from bulk to the surface and subsequent recombination on the surface states.…”

Влияние погружения слоев пористого кремния в водные растворы Fe(NO-=SUB=-3-=/SUB=-)-=SUB=-3-=/SUB=- на фотолюминесценцию в процессе длительного хранения

“…Старение слоев PS индуцирует нестабильность сигнала PL, поскольку под воздействи-ем атомов кислорода происходит разрушение кремний-водородных (Si−H) связей в нанокристаллах (NC) крем-ния, а кислород может оставаться на поверхности или диффундировать вглубь кремниевых NC. Последнее при-водит к уменьшению размеров NC и, следовательно, к сдвигу максимума пика PL в область больших энергий фотонов ( " голубому" сдвигу) [17,18]. Для стабилизации интенсивности PL PS и в дальней-шем для их внедрения в приборные структуры необ-ходимо модифицировать поверхностную структуру PS.…”