Experimental study of the energy-band structure of porous silicon

Andersen, O. K.; Veje, E.

doi:10.1103/physrevb.53.15643

Cited by 59 publications

(53 citation statements)

References 47 publications

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“…There is bound to be a disagreement between theoretically calculated values and experimental values as the former are obtained by usually considering a single QD while experiments are usually carried out on an assembly of QDs. This has been noticed earlier in the context of photoluminescence spectra [7,8] and band gap discrepancies [9]. We are currently examining the experimental consequences of the calculations reported herein.…”

Section: Resultssupporting

confidence: 76%

A mean field approach to Coulomb blockade for a disordered assembly of quantum dots

2008

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The Coulomb blockade (CB) in quantum dots (QDs) is by now well documented. It has been used to guide the fabrication of single electron transistors. Even the most sophisticated techniques for synthesizing QDs (e.g. MOCVD/MBE) result in an assembly in which a certain amount of disorder is inevitable. On the other hand, theoretical approaches to CB limit themselves to an analysis of a single QD. In the present work we consider two types of disorders: (i) size disorder; e.g. QDs have a distribution of sizes which could be unimodal or bimodal in nature. (ii) Potential disorder with the confining potential assuming a variety of shapes depending on growth condition and external fields. We assume a Gaussian distribution in disorder in both size and potential and employ a simplified mean field theory. To do this we rely on the scaling laws for the CB (also termed as Hubbard U ) obtained for an isolated QD [1]. We analyze the distribution in the Hubbard U as a consequence of disorder and observe that Coulomb blockade is partially suppressed by the disorder. Further, the distribution in U is a skewed Gaussian with enhanced broadening.

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Section: Resultssupporting

confidence: 76%

A mean field approach to Coulomb blockade for a disordered assembly of quantum dots

2008

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“…We have to note that a similar temperature quenching activation energy (around 70 meV) was observed also in porous Si. 20 On the other hand the temperature dependence of the integrated continuous PL signal (black squares in Figure 5a) shows a stronger quenching with an activation energy of E a = 25 meV.…”

Section: Lettermentioning

confidence: 95%

Coexistence of 1D and Quasi-0D Photoluminescence from Single Silicon Nanowires

2011

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Single silicon nanowires (Si-NWs) prepared by electron-beam lithography and reactive-ion etching are investigated by imaging optical spectroscopy under variable temperatures and laser pumping intensities. Spectral images of individual Si-NWs reveal a large variability of photoluminescence (PL) along a single Si-NW. The weaker broad emission band asymmetrically extended to the high-energy side is interpreted to be due to recombination of quasi-free 1D excitons while the brighter localized emission features (with significantly variable peak position, width, and shape) are due to localization of electron-hole pairs in surface protrusions acting like quasi-0D centers or quantum dots (QDs). Correlated PL and scanning electron microscopy images indicate that the efficiently emitting QDs are located at the Si-NW interface with completely oxidized neck of the initial Si wall. Theoretical fitting of the delocalized PL emission band explains its broad asymmetrical band to be due to the Gaussian size distribution of the Si-NW diameter and reveals also the presence of recombination from the Si-NW excited state which can facilitate a fast capture of excitons into QD centers.

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“…In addition to the intensity variations, peak position of every spectrum shows a stoke shift with excitation energy from 1.8 to 1.91 eV, within the rage of our observation. The origin of the peak shift [14,15] is yet not well understood.…”

Section: Resultsmentioning

confidence: 99%