Two Meyer-Neldel Rules in Porous Silicon

International audienceWe observe that light soaking for short durations and thermal quenching in nanocrystalline porous silicon (PS) produce metastable states. These metastable states show higher dark current, higher and photo current, large photoluminescence and weaker electron spin resonance (ESR) signal. However, long exposures to light produce opposite effect. The metastable states are stable against sub band gap light exposures. These metastable states can be removed by annealing at 150 0C for 1 hour. ESR shows the presence of a-Si phase (g~2.0058, 6.4G) in PS sample, but it is not sufficient to explain all experimental results. Rather, our experiments suggest that light soaking causes more than one type of defects in porous silicon. The structural changes involving the movement of hydrogen present at the surface of PS or at PS/a-Si interface may be responsible for these effects

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“…This conclusion is in line with von-Bardeleben et al [18]. Table 1 [23,24]. A similar conclusion was also done by Ben-Chorin et al…”

Section: Resultssupporting

confidence: 81%

Light and thermally induced metastabilities in electrochemically etched nanocrystalline porous silicon

Mandal¹,

Awasthi²,

Konar³

et al. 2009

Philosophical Magazine

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“…This suggests anti MNR behavior is possible in this kind of ncSi-SiC:H alloy material also, which has not been reported previously, and certainly needs more exploration. It seems likely that the transport mechanism in the MNR regime in this material is not thermally activated hopping 49 as suggested in the Ref. [53].…”

Section: E a (Ev)mentioning

confidence: 78%

Influence of the statistical shift of Fermi level on the conductivity behavior in microcrystalline silicon

2008

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The electrical conductivity behavior of highly crystallized undoped hydrogenated microcrystalline silicon (µc-Si:H) films having different microstructures was studied. The dark conductivity is seen to follow Meyer Neldel rule (MNR) in some films and anti MNR in others, depending on the details of microstructural attributes and corresponding changes in the effective density of states distributions. A band tail transport and statistical shift of Fermi level are used to explain the origin of MNR as well as anti-MNR in our samples. We present the evidence of anti MNR in the various experimental transport data of µc-Si:H materials reported in literature and analyze these data together with ours to show the consistency and physical plausibility of statistical shift model. The calculated MNR parameters and other significant material parameters derived therefrom are tenable for a wide microstructural range of the µc-Si:H system.

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“…All the various experimental data about the temperature dependence of the DC conductivity have been represented and analyzed according to the Meyer-Neldel rule [97]:…”

Section: Conduction In Psmentioning

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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Two Meyer-Neldel Rules in Porous Silicon

Cited by 85 publications

References 28 publications

Light and thermally induced metastabilities in electrochemically etched nanocrystalline porous silicon

Light and thermally induced metastabilities in electrochemically etched nanocrystalline porous silicon

Influence of the statistical shift of Fermi level on the conductivity behavior in microcrystalline silicon

Porous Silicon

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