Photoluminescene study of radiative recombination in porous Si

by Chun Wang

Publisher: National Library of Canada in Ottawa

Written in English
Published: Downloads: 866
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Thesis (M.A.Sc.)--University of Toronto, 1993.

The visible photoluminescence originates from radiative recombination between discrete energy levels in quantum well. Photoluminescence time resolved spectra (PL-TRS) and decay curves of photoluminescence (PL-DC) in micro- and nanosecond range at different temperatures (10 K-room) on anodically etched boron-doped silicon are presented. The main radiative recombination, which generates the PL signal, proceeds by band-to-band transitions involving an e-h pair, i.e. it is a bi-molecular process. Thus, the radiative recombination rate reflects the bi-molecular character of the process: 𝑅 ()= 𝑡 𝑡()𝑝𝑡 𝑡() (2). With HfO 2 filled into the microcavities of the porous single-crystal silicon, the blue photoluminescence was greatly enhanced at room temperature. On one hand, HfO 2 contributes to the light emission with the transitions of the defect levels for oxygen vacancy. On the other hand, the special filling-into-microcavities structure of HfO 2 leads to the presence of ferroelectricity, which greatly. This paper reports a study of Shockley-Read-Hall, radiative, and Auger recombination processes in a series of molecular beam epitaxy grown InAs/InAsSb mid-wavelength infrared and long-wavelength infrared type-II superlattice samples using temperature- and excitation-density-dependent photoluminescence measurements, which are carried out from 12 to 77 K with excitation densities .

Photoluminescence spectra in the near‐band‐gap region of Si 1-x Ge x alloys (x= and ) grown on Si() substrates by molecular beam epitaxy have been measured at and 12 K. Takeoka S., Fujii M. & Hayashi S. Size-dependent photoluminescence from surface-oxidized Si nanocrystals in a weak confinement regime. Phys. Rev. B 62, – (). Ondič L. et al.. A complex study of the fast blue luminescence of oxidized silicon nanocrystals: the role of the core. Nanoscale 6, – (). High-intensity photoluminescence (PL) was obtained for as-prepared porous Si, which was produced by anodization at high concentrations of ethanol. When the porous Si was exposed to ambient air, oxygen rapidly oxidized the surface of the porous Si, and the PL showed a blue shift in wavelength with a slight decrease in intensity within a short time. Photoluminescence Recombination mechanisms The return to equilibrium, also known as "recombination," can involve both radiative and nonradiative processes. The amount of PL emission and its dependence on the level of photo- excitation and temperature are directly related to the dominant recombination process. Material quality.

  We applied photoacoustic (PA), photoluminescence (PL), photoluminescence excitation (PLE), and atomic force microscopy (AFM) techniques on porous silicon (PS) layers to study the influence of chemical etching by low-concentration hydrofluoric acid. The photoluminescence spectra of porous silicon and their temperature dependences and transformations on aging are studied. It is shown that the infrared band prevailing in the spectra of as-prepared samples is due to exciton recombination in silicon crystallites. On aging, a well-pronounced. Porous silicon is excited using near-infrared femtosecond pulsed and continuous wave radiation at an average intensity of {approx}10{sup 6} W/cm{sup 2} (8x10{sup 10} W/cm{sup 2} peak intensity in pulsed mode). Our results demonstrate the presence of micron-size regions for which the intensity of the. To explain our results we assumed a model in which the multibarrier structure is formed by larger Si crystallites or wires (quantum well) surrounded by Si crystallites with diameters in the nanometer range (barrier region). The visible photoluminescence originates from radiative recombination between discrete energy levels in a quantum well.

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Photoluminescence Study of Radiative Recombination in Porous Silicon - Volume - Chun Wang, Franco Gaspari, Stefan Zukotynski. Photoluminescence study of radiative recombination in porous silicon Article (PDF Available) in Applied Physics Letters 62(21) - June with 64 Reads How we measure 'reads'.

Photoluminescence in porous Si films has been studied in the temperature range from 15 to K. The luminescence peak is found to shift to higher frequency with increasing temperature.

Above K the luminescence intensity shows strong thermal quenching with an activation energy of 60 meV. Below K photoluminescence decay data obtained using quadrature frequency resolved spectroscopy Cited by:   We have measured photoluminescence (PL) and Raman spectra of porous silicon (PS) thin films subjected to irradiation with 30 keV He + ion beams.

Fluence has been changed between 10 14 and 10 16 ions/cm results show a decrease of the photoluminescence intensity by increasing the ion fluence, probably due to the formation of induced non-radiative recombination by: 8. In order to study radiative and non-radiative recombination centers and their role in PL formation on the surface of porous silicon samples in more details kinetic curves of luminescence degradation were obtained for the case of samples irradiation with a continuous laser irradiation at the wavelength of Photoluminescene study of radiative recombination in porous Si book.

Xu YK, Adachi S () Multiple-peak structure in porous Si photoluminescence. J Appl Phys (12), Artn doi/ CrossRef Google Scholar Yamada M, Kondo K () Comparing effects of vacuum annealing and dry oxidation on the photoluminescence of porous Si.

Request PDF | Kinetics of photoluminescence of porous silicon studied by photo-luminescence excitation spectroscopy and time-resolved spectroscopy | Photoluminescence. The PSi layers were produced using an electrochemical etching process in an aqueous solution of HF (48%) and ethanol, in a volume ratio ofrespectively, on p-type Si substrate of Ω cm −2 and [] crystalline orientation, from Polish Corporation of America-USA.

Several samples of 14 × 14 mm were cut and cleaned using the standard RCA method.Cited by: 4. The other component of PL is shown to be sensitive to the strength of the Si-O-Si bond related absorption.

Based on the previous reports and the results shown here, a possible PL mechanism in porous silicon is emerged. The eV band is the lowest energy state among radiative recombination.

By varying the laser excitation density from 60 to W/cm 2, we shed the light on the radiative recombination modes occurring within the Si nanocrystals (SiNCs) generated along the pSiNWs. We study as well the temperature-dependent PL of the pSiNWs in the range 10 to K.

Based on both laser excitation density and temperature-dependent PL. The analysis of XPS and SEM demonstrate that the high oxidization of HNO 3 makes more O atoms absorption on the surface, and non-radiative recombination centers decrease in this way.

As a result, photoluminescence intensity enhances, and a good stable luminescence of porous silicon is obtained. We study the recombination mechanism of the visible photoluminescence (PL) S-band in p-doped porous Si layers by time-resolved photoluminescence.

From the observed ``stretched-exponential'' PL decays we present a simple yet accurate evaluation method for lifetime distributions G(τ) and average recombination lifetimes. The average lifetimes feature a strong temperature dependence and a. The photoluminescence (PL) response of porous Si has potential applications in a number of sensor and bioimaging techniques.

However, many questions still remain regarding how to stabilize and enhance the PL signal, as well as how PL responds to environmental factors. Regenerative electroless etching (ReEtching) was used to produce photoluminescent porous Si directly from Si powder.

Photoluminescence (abbreviated as PL) is light emission from any form of matter after the absorption of photons (electromagnetic radiation). It is one of many forms of luminescence (light emission) and is initiated by photoexcitation (i.e.

photons that excite electrons to a higher energy level in an atom), hence the prefix photo. Following excitation various relaxation processes typically. The photoluminescence (PL) study in porous silicon (PS) with decreasing Si crystallites size among the pores was reported.

The PL appearance is attributed to electronic confinement in columnar-like (or dotlike) structures of porous silicon. Three different pore diameter PS samples were prepared by electrochemical etching in HF-based solutions.

Changes in porous silicon and Si crystallite size. Abstract. The photoluminescence of mesoporous silicon and silicon nanocrystals has received enormous study over the last 25 years. The spectroscopic nature and efficiency of various emission bands from the near-infrared to the ultraviolet are briefly reviewed, as are mechanistic studies on individual nanocrystals.

CONFERENCE PROCEEDINGS Papers Presentations Journals. Advanced Photonics Journal of Applied Remote Sensing. Highlights We attain ultrafast recombination lifetimes of and ns in the Se-treated Si porous structure. The fast recombination rate is considered to origin from the direct radiative recombination induced by surface modification.

Excitation wavelength- and temperature-dependent PL spectra are carried out. A near-infrared emission band with wavelength around the optimal energy region. A significant enhancement of the photoluminescence (PL) efficiency is observed for aqueous suspensions of porous silicon nanoparticles (PSiNPs) coated by bioresorbable polymers, i.e., polylactic-co-glycolic acid (PLGA) and polyvinyl alcohol (PVA).

PSiNPs with average size about nm prepared by mechanical grinding of electrochemically etched porous silicon were dispersed in water. Luminescent PSi consists of a network of silicon nanocrystals (nc-Si) with typical sizes of 2 to 5 nm separated by nanometer-sized pores.

The origin of PL is assumed to be the radiative recombination of charge carriers, i.e., electrons and holes coupled in excitons in nc-Si. The quantum confinement for change carriers in nc-Si leads to a.

External radiative quantum efficiency vs. the rate of electron–hole pair generation and recombination in steady state. The solid line is a fit to the data that accounts for interface, radiative. Photoluminescence in the visible.

A typical PL spectrum observed for a layer of ~ nm octahedral Si NP’s under eV continuous wave excitation is shown in Fig. 2(a) – black curve – with the corresponding power dependence of its intensity in Fig. 2(b), depicted in double logarithmic the latter, we conclude that the PL intensity increases superlinearly with the.

The temperature dependence and the temporal decay of photoluminescence from thermally-oxidized porous silicon have been studied under or eV excitation which is below or above the optical bandgap value of eV determined from the luminescence excitation spectrum.

No significant difference between luminescence spectra under the subgap and the overgap excitation is observed at. Photoluminescence mechanisms in porous oxidized Si were investigated.

We observed marked enhancement in the photoluminescence intensity of porous Si when it was oxidized at high temperatures from to °C in dry oxygen. The photoluminescence decay of both as‐prepared and dry‐oxidized porous Si was intrinsically nonexponential.

As reported by other groups, the photoluminescence. silicon electron-hole recombination elemental semiconductors interface electron states luminescence of inorganic solids photoluminescence porous materials porous Si photoluminescence interface states type II like recombination mechanism model radiative recombinations energy levels quantum confinement energy threshold Si-SiO/sub 2/ Charge.

The structural, optical, and photoluminescence properties of porous silicon (PSi)/titanium dioxide (TiO2) nanostructures were investigated. PSi structures consisting of macro- and mesoporous layers were fabricated by metal-assisted chemical etching, and then TiO2 was introduced inside the PSi matrix using the atomic layer deposition technique.

We performed scanning electron microscopy. The results of an experimental study of Raman scattering, photoluminescence, and light absorption and reflection in porous silicon layers obtained by electrochemical etching of single-crystal wafers are presented.

It is concluded on the basis of an analysis of the experimental data that the centers responsible for radiative and nonradiative recombination in this material are of a multiple. The discovery of visible photoluminescence (PL) from porous silicon and then silicon nanocrystals (Si-NCs) has stimulated a great deal of interest in this material mainly due to a number of promising potential applications, like, for instance, light emitting diodes [] or silicon-based lasers [].Although the quantum efficiency of Si-NCs emission gives hope for future device applications, it.

We have used anodization techniques to process porous surface regions in p‐type Czochralski Si and in p‐type Si Ge epitaxial layers grown by molecular beam epitaxy. The SiGe layers were unrelaxed before processing. We have observed strong near‐infrared and visible light emission from both systems.

Analysis of the radiative and nonradiative recombination processes indicate that. The Letter proposes a model to explain the PL mechanism in porous silicon. It was inspired by type II semiconductor interface PL behaviour. In this model, the PS radiative recombinations involve energy levels in the silicon oxide layer.

This model takes into account quantum confinement and the energy threshold above which PS PL is observed. values which will ultimately die out through recombination Recombination Processes in Semiconductors Typical recombination processes which can occur m semiconductors are free excitons (Fx), band-to-band (e-h), carrier to localised impurity states (e-A, D-h) and carriers bound to other impurities (D-A), these are illustrated in.The paper is concerned with the study of the photoluminescence (PL) lifetime distribution of a-Si: H and a-Ge: H, down to the nanosecond (ns) region using a newly developed dual-phase, double.Temperature variation of radiative recombination rate of electron–hole pairs in hydrogenated amorphous silicon (a-Si:H) films has been obtained from measurements of photoluminescence (PL) by means of frequency resolved spectroscopy (FRS).

The radiative recombination rate increases with increasing temperature.