EXCITONIC SIDE BANDS OF INNER-SHELL EXCITATIONS IN RARE GAS SOLIDS

Valence-exciton luminescence under inner-shell excitation of the rare gas solids Xe, Kr, and Ar has been measured using time-resolved photoluminescence. Two different processes for exciton creation can be distinguished: creation of "prompt" excitons immediately after excitation (within the experimental time resolution), and creation of "delayed" excitons through electron–hole recombination. The decay structure of the exciton emission in the range of inner-shell excitation is characterized by the coexistence of the two processes. Time-resolved excitation spectra near the 2p edge in Ar, the 3d edge in Kr, and the 4d edge in Xe are discussed. The process of prompt exciton creation is strongly enhanced above an excitation threshold at the energy position of the ionization limit of the core state plus the energy of the valence free exciton.

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INNER-SHELL TRANSITIONS AND SECONDARY EXCITONS IN SOLID XE AND KR

International Journal of Modern Physics B ◽

10.1142/s0217979201008457 ◽

2001 ◽

Vol 15 (28n30) ◽

pp. 3695-3699 ◽

Cited By ~ 3

Author(s):

S. VIELHAUER ◽

E. GMINDER ◽

M. KIRM ◽

V. KISAND ◽

E. NEGODIN ◽

...

Keyword(s):

Time Window ◽

Free Exciton ◽

Threshold Energy ◽

Rare Gas ◽

Excitation Spectra ◽

Electron Hole ◽

Time Resolved ◽

Short Time Window ◽

Short Time ◽

Time Resolved Photoluminescence

Time-resolved photoluminescence of the exciton emission in rare gas solids has been measured for excitation in the range of inner-shell transitions. The excitons are created both 'promptly' (within the experimental time resolution) and 'delayed' through electron-hole recombination. Excitation spectra at the 4d edge in Xe and the 3d edge in Kr are discussed. An outstanding feature of the time resolved spectra is the strong resonance that appears in a short time window above a threshold energy, which is the sum of the ionisation energy of the core level and the energy of the (valence) free exciton.

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Optical Properties of Ingan/GaN Multi Quantum Well Structures

MRS Proceedings ◽

10.1557/proc-482-631 ◽

1997 ◽

Vol 482 ◽

Cited By ~ 12

Author(s):

J. P. Bergman ◽

N. Saksulv ◽

J. Dalfors ◽

P. O. Holtz ◽

B. Monemar ◽

...

Keyword(s):

Quantum Wells ◽

Multiple Quantum ◽

Recombination Rates ◽

Energy Position ◽

Electron Hole ◽

Time Resolved ◽

Quantum Well Structures ◽

Lower Energy Band ◽

Time Resolved Photoluminescence ◽

Multi Quantum Well

AbstractA set of GaN/InGaN multiple quantum wells (QWs) with well thickness 30 Å and barrier thickness 60 Å were grown by MOCVD on sapphire substrates. The n-type Si doping of the InGaN QWs was varied, in order to produce a different electron concentration in the QWs for the different samples. Optical spectra were obtained by time resolved photoluminescence spectroscopy. The data show weak excitonic spectra from the QWs as well as a broad deeper emission with a much stronger intensity. The spectral shape becomes narrower and the energy position shifts to higher energies with increasing doping. The two different emissions are not easily separated in CW or time integrated spectra, but are clearly observed in a time resolved spectral measurement due to their different recombination rates. The deeper emission has a long and non-exponential decay, with an average decay time in the order of several hundred nanoseconds. The higher energy exciton emission has a much faster decay of about 1 ns. The lower energy band is tentatively explained as due to separately localized electron-hole (e-h) pairs in the QW.

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AN ANALYSIS OF ELECTRON–HOLE RECOMBINATION IN SOLID KRYPTON USING TIME-RESOLVED VUV-LUMINESCENCE SECTROSCOPY

Surface Review and Letters ◽

10.1142/s0218625x02002956 ◽

2002 ◽

Vol 09 (02) ◽

pp. 783-788 ◽

Cited By ~ 2

Author(s):

V. KISAND ◽

M. KIRM ◽

S. VIELHAUER ◽

G. ZIMMERER

Keyword(s):

Free Exciton ◽

Band Gap Energy ◽

Electron Hole ◽

Time Resolved ◽

Detailed Model ◽

Model Calculations ◽

Exciton Decay ◽

Solid Krypton ◽

First Time ◽

Hole Recombination

For the first time, the free exciton (FE) VUV-luminescence decay curves were systematically investigated in solid Kr using photoexcitation in the energy region above band gap energy. Delayed electron–hole recombination and "prompt" (in terms of the time resolution of the experimental setup) creation of secondary excitons were separated using the time-resolved experimental technique. A detailed model for the dynamics of electron–hole recombination into the FE state was developed. The delayed component of the free exciton decay curve was reproduced with model calculations, including thermalization of the carriers via scattering on acoustic phonons, and the recombination cross-section, which depends on the actual carrier temperatures. A satisfactory agreement between experiment and theory was found.

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Robust single-mode lasers based on hexagonal CdS microflakes

Journal of Materials Chemistry C ◽

10.1039/d0tc02703k ◽

2020 ◽

Vol 8 (32) ◽

pp. 11201-11208

Author(s):

Yang Mi ◽

Yaoyao Wu ◽

Jinchun Shi ◽

Sheng-Nian Luo

Keyword(s):

Radiative Recombination ◽

Single Mode ◽

Whispering Gallery Mode ◽

Radiative Recombination Rate ◽

Electron Hole ◽

High Quality ◽

Time Resolved ◽

Whispering Gallery ◽

Electron Hole Plasma ◽

Time Resolved Photoluminescence

We have achieved single-mode whispering-gallery-mode lasing in CdS microflakes with sharp linewidth (∼0.12 nm) and high quality factor (∼4200). Such lasers are superior to previous CdS lasers in these lasing parameters. Through time-resolved photoluminescence measurements, electron–hole plasma recombination is established to be the lasing mechanism. The radiative recombination rate of CdS microflakes is enhanced by a factor of ∼4.7 due to the Purcell effect.

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Nanocrystalline Silicon for Optoelectronic Applications

MRS Bulletin ◽

10.1557/s0883769400030244 ◽

1998 ◽

Vol 23 (4) ◽

pp. 33-38 ◽

Cited By ~ 42

Author(s):

Leonid Tsybeskov

Keyword(s):

Binding Energy ◽

Light Emission ◽

Crystalline Silicon ◽

Free Exciton ◽

Nanocrystalline Silicon ◽

Momentum Conservation ◽

Exciton Binding Energy ◽

Electron Hole ◽

Energy Plus ◽

Hole Recombination

Light emission in silicon has been intensively investigated since the 1950s when crystalline silicon (c-Si) was recognized as the dominant material in microelectronics. Silicon is an indirect-bandgap semiconductor and momentum conservation requires phonon assistance in radiative electron-hole recombination (Figure 1a, top left). Because phonons carry a momentum and an energy, the typical signature of phonon-assisted recombination is several peaks in the photoluminescence (PL) spectra at low temperature. These PL peaks are called “phonon replicas.” High-purity c-Si PL is caused by free-exciton self-annihilation with the exciton binding energy of ~11 meV. The TO-phonon contribution in conservation processes is most significant, and the main PL peak (~1.1 eV) is shifted from the bandgap value (~1.17 eV) by ~70 meV—that is, the exciton binding energy plus TO-phonon energy (Figure 1a).

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Auger Recombination in Antimony-Based, Strain-Balanced, Narrow-Band-Gap Superlattics

MRS Proceedings ◽

10.1557/proc-484-83 ◽

1997 ◽

Vol 484 ◽

Cited By ~ 1

Author(s):

J. T. Olesberg ◽

Thomas F. Boggess ◽

S. A. Anson ◽

D.-J. Jan ◽

M. E. Flatté ◽

...

Keyword(s):

Auger Recombination ◽

Growth Direction ◽

Bandgap Energy ◽

Recombination Rates ◽

Electron Hole ◽

Time Resolved ◽

All Optical ◽

Semi Empirical ◽

The Impact ◽

Hole Recombination

AbstractTime-resolved all-optical techniques are used to measure the density and temperature dependence of electron-hole recombination in an InAs/GaInSb/InAs/AlGaInAsSb strain-balanced superlattice grown by molecular beam expitaxy on GaSb. This 4 μm bandgap structure, which has been designed for suppressed Auger recombination, is a candidate material for the active region of mid-infrared lasers. While carrier lifetime measurements at room temperature show unambiguous evidence of Auger recombination, the extracted Auger recombination rates are considerably lower than those reported for bulk materials of comparable bandgap energy. We find that the Auger rate saturates at carrier densities comparable to those required for degeneracy of the valence band, illustrating the impact of Fermi statistics on the Auger process. The measured results are compared with theoretical Auger rates computed using a band structure obtained from a semi-empirical 8-band K.p model. We find excellent agreement between theoretical and experimental results when Umklapp processes in the growth direction are included in the calculation. Measured recombination rates from 50 to 300 K are combined with calculated threshold carrier densities to determine a material To value for the superlattice.

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Time-resolved photoluminescence of dense electron–hole plasmas in InGaAsP films

10.1364/cleo.1985.thm42 ◽

1985 ◽

Author(s):

A. J. TAYLOR ◽

J. M. WIESENFELD

Keyword(s):

Electron Hole ◽

Time Resolved ◽

Time Resolved Photoluminescence

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Charge Separation Between Strain Coupled Quantum Dots in a Self-Assembled InAs Quantum Dot Structure

MRS Proceedings ◽

10.1557/proc-571-153 ◽

1999 ◽

Vol 571 ◽

Author(s):

W. V. Schoenfeld ◽

T. Lundstrom ◽

P. M. Petroff

Keyword(s):

Quantum Dots ◽

Quantum Dot ◽

Preliminary Data ◽

Charge Separation ◽

Electron Hole ◽

Coupled Quantum Dots ◽

Time Resolved ◽

Inas Quantum Dot ◽

Storage Times ◽

Time Resolved Photoluminescence

ABSTRACTWe present an InAs QDs structure designed to separate and store photo-generated electron-hole pairs. Charge separation in the structure is demonstrated using power dependent photoluminescence and biased photoluminescence. Preliminary data from time resolved photoluminescence suggest storage times in the device in the μsec range.

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