ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
We analyzed the photoluminescence (PL) mechanisms of porous silicon, and in particular, the origin of the PL high quantum efficiency (QE) at room temperature. For this we used postformation treatments, anodic oxidation, and hydrofluoric acid (HF) etching (known for their strong QE enhancement effect) correlated with a PL time resolved analysis. A third parameter was the temperature which, for heating above room temperature, gave a reversible quenching of the PL. All three parameters give a similar evolution of the PL decay shape, which we consider to originate from the same evolution of the carrier dynamics. Porous silicon is described as an undulating wire. The high QE at room temperature is attributed to carrier localization inside minima of the fluctuating potential along the wire; these considerations are extended to another porous material: amorphous porous silicon. Anodic oxidation and HF dissolution diminish the wire size, giving a reduction of the localization length of the carriers and progressive suppression of the nonradiative recombination channel. A simple model permits one to link the changes of the PL decay shape to the QE evolution. The nonexponential PL decay shape is interpreted as being due to a distribution of nonradiative recombination rates, the value of the nonradiative recombination rate being limited by a tunneling effect. This highly simplified model explains the origin of the nonexponential decay shape, its modification and gives a good description of the QE evolution as a function of temperature, oxidation level, or porosity. © 1996 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.363076
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