Investigation of optical properties of free-standing porous silicon films by absorption and mirage effect

Vincent, Gilbert; Leblanc, François; Sagnes, I.; Badoz, P. A.; Halimaoui, A.

doi:10.1016/0022-2313(93)90136-b

Cited by 35 publications

(24 citation statements)

References 11 publications

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“…Vincent et al [27] suggested that the red-shift of transmission curves may be explained by the formation of a hypothetical (Si, O, H) absorbing compound, which is less transparent than PS, instead of a pure oxide, or a change in the surface or near-surface state energy depending on H or O passivation. Kumar et al [30] obtained theoretically a conclusion that an increase in oxygen termination atoms produces a decrease in the energy gap of the NSP units.…”

Section: Resultsmentioning

confidence: 99%

“…Vincent et al [27] observed a red-shift of the transmission curve under thermal oxidation at 400 °C for 1 h. We have reported that the transmission curve red-shifts and then blue-shifts during thermal oxidation process [26]. In this paper, we present a detailed study of the evolution of the optical absorption of the free-standing PS films under thermal oxidization at 200 °C in air.…”

Section: Introductionmentioning

confidence: 82%

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Optical absorption property of oxidized free-standing porous silicon films

Guo

Liu

et al. 2000

Pure and Applied Chemistry

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Abstract:We have systematically studied the evolution of the optical absorption of freestanding PS films during thermal oxidation at 200°C in air. Our experiment results show the evolution of transmission curve is quite complicated, which red-shifts first and then blueshifts during thermal oxidation. At the same time, the transmission at the low energy decreases first and then increases. We propose an explanation as follows: (1) the energy gap associated with each crystallite should increase during thermal oxidation process, due to the quantum confinement effect; (2) the energy gap should decrease with an increase in oxygen termination atoms. Both the increasing of the gap due to the quantum confinement effect and the decreasing of the gap due to the Si-O bond formation cause a complicated evolution of optical absorption.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 82%

Optical absorption property of oxidized free-standing porous silicon films

Guo

Liu

et al. 2000

Pure and Applied Chemistry

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“…Given the distribution of pores and structure sizes always present in PS, the absorption spectrum is the sum of widely different microscopic absorption processes. The absorption coefficient α has been measured in PS by optical transmission [46], photoluminescence excitation (PLE) [47], and photothermal deflection spectroscopy (PDS) [48]. A quantitative evaluation has to take into account the quantity of matter present in the layer.…”

Section: What Is the Nature Of The Ps Fundamental Band Gap?mentioning

confidence: 99%

Porous Silicon

Ossicini¹,

Pavesi²,

Priolo³

2003

Springer Tracts in Modern Physics

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In 1990 it was proposed that Si when rendered porous can be an efficient light emitting system, as efficient as many III-V semiconductor systems [1]. The reason for this was attributed to the low dimensionality of the surviving Si skeleton. In addition other effects were recognized: (1) the large photon extraction efficiency due to the decrease in the effective refractive index and (2) the confinement of the carriers in regions free of recombination centers. After this very surprising report, a huge number of papers was published trying to understand the optical properties of porous silicon (PS) and the physical mechanism at the heart of the large luminescence efficiency. Soon it was realized that PS is a very fragile and highly reactive material so that many of its properties are age dependent and unstable. Over the years, sizeable progress was made both in terms of improvement of its stability and in term of efficiency of the device. Microelectronics compatibility of PS was demonstrated and integration of driving circuits with a light emitting element was performed [2]. At the same time microcavities with improved light emission properties were demonstrated [3]. At the end of 2000 another paper shocked the silicon community: the report on light amplification or optical gain in silicon nanocrystals [4]. This paper raises big hopes of the development of a silicon laser even though it is not yet clear whether PS can be used as an active material.In this chapter we will try to review the most important results about the exploitation and the understanding of the properties of PS. The chapter is divided into six parts. The first introduces how porous silicon is made. The second is aimed to demonstrate that the structure of PS is a collection of nanometric objects that contribute to the light emission process. The relevant role of the surface chemistry is underlined. The third and fourth parts discuss the essential features of the absorption and luminescence of PS in order to discriminate between the models of the recombination mechanisms. The fifth presents recent progress in the field of electrical properties of PS. The section six is an overview of the application of PS in light emitting diodes.In the last few years various conference proceedings [5], review articles [6] and edited books [7] have been published on PS.

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“…Another problem caused by voids is the determination of x. One way to deal with this is to multiply the actual thickness of a PS film by (1-P), 8 where porosity P is defined as the volume percentage of the voids in PS samples. This approximation may not be appropriate because it scales a one-dimensional quantity with a three-dimensional ratio.…”

Section: (A) Transmission Measurementmentioning

confidence: 99%

Photoluminescence Excitation Spectroscopy of Porous Silicon

Haegel¹,

Wang²

1994

Porous Silicon

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Photoluminescence excitation spectroseopy (PLE) has been used to study the absorption processes leading to the emission of visible luminescence in porous silicon (PS). In this review, we summarize the PLE data that have been presented and compare the results to the absorption properties obtained through direct transmission, synchrotron reflectivity, and other techniques. PLE results indicate a correlation between the primary absorption mechanism in PS and the one that leads to the emission of the visible luminescence. This absorption process has a exponential edge followed by a porositydependent increase at higher energies. Models for the interpretation of PLE data, based on recent calculations for silicon quantum wires, are reviewed. Additional work is required in the area of near-band-edge absorption and polarization effects in order to understand the absorption mechanisms in this material.

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Investigation of optical properties of free-standing porous silicon films by absorption and mirage effect

Cited by 35 publications

References 11 publications

Optical absorption property of oxidized free-standing porous silicon films

Optical absorption property of oxidized free-standing porous silicon films

Porous Silicon

Photoluminescence Excitation Spectroscopy of Porous Silicon

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