Determination of the free exciton energy in ZnO nanorods from photoluminescence excitation spectroscopy

2007 ◽  
Vol 102 (1) ◽  
pp. 013511 ◽  
Author(s):  
H. P. He ◽  
Z. Z. Ye ◽  
S. S. Lin ◽  
H. P. Tang ◽  
Y. Z. Zhang ◽  
...  
Keyword(s):  
Free Exciton ◽  
Zno Nanorods ◽  
Photoluminescence Excitation ◽  
Exciton Energy

Photoluminescence Excitation Spectroscopy of Carbon-Doped Gallium Nitride

1998 ◽  
Vol 537 ◽  
Author(s):  
E. E. Reuter ◽  
R. Zhang ◽  
T. F. Kuech ◽  
S. G. Bishop
Keyword(s):  
Complete Characterization ◽  
Photoluminescence Excitation ◽  
Yellow Luminescence ◽  
Broad Excitation Band ◽  
Carbon Doped ◽  
Sapphire Substrates ◽  
Red Luminescence ◽  
Unusual Shape

AbstractWe have done a comparative study of carbon-doped GaN and undoped GaN utilizing photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopies in order to investigate deep levels involved in yellow luminescence (YL) and red luminescence (RL). When the GaN was excited by above-bandgap light, red luminescence (RL) centered at 1.82 eV was the dominant below-gap PL from undoped GaN, but carbon-doped GaN below-gap PL was dominated by yellow luminescence (YL) centered at 2.2 eV. When exciting PL below the band-gap with 2.4 eV light, undoped GaN had a RL peak centered at 1.5 eV and carbon-doped GaN had a RL peak centered at 1.65 eV. PLE spectra of carbon-doped GaN, detecting at 1.56 eV, exhibited a strong, broad excitation band extending from about 2.1 to 2.8 eV with an unusual shape that may be due to two or more overlapping excitation bands. This RL PLE band was not observed in undoped GaN. We also demonstrate that PL spectra excited by below gap light in GaN films on sapphire substrates are readily contaminated by 1.6-1.8 eV and 2.1-2.5 eV chromium-related emission from the substrate. A complete characterization of the Cr emission and excitation bands for sapphire substrates enables the determination of the excitation and detection wavelengths required to obtain GaN PL and PLE spectra that are free of contributions from substrate emission.

Free Exciton Energy Transfer in KrAu Sandwiches

1981 ◽  
Vol 106 (1) ◽  
pp. 183-192 ◽  
Author(s):  
N. Schwentner ◽  
G. Martens ◽  
H. W. Rudolf
Keyword(s):  
Energy Transfer ◽  
Free Exciton ◽  
Exciton Energy

STUDY OF NANOSTRUCTURES OF ZINC OXIDE SYNTHESIZED BY LOW-TEMPERATURE HYDROTHERMAL METHOD

2018 ◽  
Vol 20 (4) ◽  
pp. 209-217
Author(s):  
S.S. Kurbanov ◽  
Sh.Z. Urolov ◽  
Z.Sh. Shaymardanov ◽  
R.R. Jalolov
Keyword(s):  
Low Temperature ◽  
Hydrothermal Method ◽  
Emission Band ◽  
Free Exciton ◽  
Zno Nanorods ◽  
Growth Direction ◽  
Orange Emission ◽  
Yellow Orange ◽  
Violet Band ◽  
Vertically Aligned

Room temperature photoluminescence (PL) properties of vertically aligned and spindle-shaped, randomly oriented ZnO nanorods synthesized by using a low temperature hydrothermal method are studied. In air, the vertically aligned ZnO nanorods oriented mainly parallel to the luminescencerecording axis exhibited only one, very strong UV emission peak at 382 nm. This band is assigned to emission of free excitons. A new violet PL band near 400 nm arises with increasing angle between the nanorod growth direction and the luminescence-recording axis. The violet band also appears under UV illumination in vacuum and vanishes after exposure to air. The randomly oriented ZnO nanorods along with free exciton related PL band reveal a broad yellow-orange emission band around 590 nm. The violet band is attributed to Zn vacancy related defects or their complexes, while the yellow-orange emission band is ascribed to oxygen interstitial related defects.

Photoluminescence of 10H-SiC

2016 ◽  
Vol 858 ◽  
pp. 269-273
Author(s):  
Anne Henry ◽  
Hiroshi Yano ◽  
Tomoaki Hatayama
Keyword(s):  
Electron Microscope ◽  
Band Gap ◽  
Transmission Electron Microscope ◽  
Lower Energy ◽  
Free Exciton ◽  
Binding Energies ◽  
Photoluminescence Spectra ◽  
Transmission Electron ◽  
First Time

The photoluminescence of the near band gap emission of 10H-SiC is revealed for the first time and detected just below 3.0 eV. The crystallinity thus polytype of the sample is controlled with transmission electron microscope analyses and Laue diffraction. On the photoluminescence spectra up to eight sharp lines are associated to the non-phonon lines of the nitrogen bound exciton even if ten are expected in 10H-SiC. Phonon replicas of these non-phonon lines are observed at lower energy with energy separations similar than those in other hexagonal SiC polytypes. At moderate temperature free-exciton replicas are also observed which allow the determination of the excitonic band gap at 3020.6 meV, value in agreement with the hexagonality of 10H-SiC of 40%. The binding energies associated to the nitrogen bound-excitons are determined as well as the ionization energies of the nitrogen donors in the 10H-SiC polytype.

PHOTOLUMINESCENCE OF A HIGH MOBILITY 2DEG IN THE FRACTIONAL QUANTUM HALL EFFECT REGIME

2007 ◽  
Vol 21 (08n09) ◽  
pp. 1455-1459
Author(s):  
D. SMIRNOV ◽  
V. V. RUDENKOV ◽  
B. M. ASHKINADZE ◽  
E. COHEN ◽  
P. C. M. CHRISTIANEN ◽  
...  
Keyword(s):  
Quantum Hall Effect ◽  
Free Exciton ◽  
Quantum Hall ◽  
High Mobility ◽  
Fractional Quantum Hall Effect ◽  
Exciton Energy ◽  
Fractional Quantum ◽  
Fractional Quantum Hall ◽  
Circularly Polarized ◽  
Spectral Changes

The magneto-PL spectra of modulation-doped, ultra-high mobility GaAs/AlGaAs single heterojunctions (HJs) were studied under a perpendicularly applied magnetic field up to 33 T and at temperatures of 0.3 and 1.2 K. The spectra show remarkable intensity redistribution between free (bulk) exciton and 2DEG-hole PL channels occurring at electron filling factors, ν = 2 and 1. At 0.3 K, significant 2DEG-hole PL spectral changes are observed near ν = 2/3 and 1/3. Several heterojunctions with 2DEG density in the range of n2D - (1 - 2.7) · 1011 cm -2 display similar features. These spectral peculiarities are attributed to the modification of the 2DEG energy spectrum caused by the e-e interaction, in particular, the recombination of valence hole with the composite (fractionally-charged) particles of the magnetized 2DEG. In HJs with lower n2D < 1011 cm -2, the observed PL evolution at ν < 1 is mainly determined by an intensity redistribution between the σ+ and σ- circularly-polarized free exciton PL components. In this case, the exciton energy is lower than the energy of the 2DEG-hole system, so that the free excitons do not dissociate near the magnetized 2DEG and thus, the 2DEG-hole PL is barely observed.

Resonant Photoluminescence Excitation in GaAs Grown Directly on Si

1988 ◽  
Vol 116 ◽  
Author(s):  
S. Zemon ◽  
C. Jagannath ◽  
S. K. Shastry ◽  
W. J. Miniscalco ◽  
G. Lambert
Keyword(s):  
Ground State ◽  
Heavy Hole ◽  
Laser Excitation ◽  
Free Exciton ◽  
Light Hole ◽  
The Other ◽  
Organometallic Vapor Phase Epitaxy ◽  
Photoluminescence Excitation ◽  
Excitation Spectra ◽  
Excitation Line

AbstractWe describe new results observed during resonant excitation in the excitonic region of GaAs grown directly on Si by organometallic vapor phase epitaxy. Two resolved features were found in the light hole photoluminescence (PL) region, one identified with a free exciton process and the other with donor-related transitions. Features which track the laser excitation line were observed and identified with a process in which a donor is excited from the n=l ground state to an n=2 excited state. The PL excitation spectra associated with these features have spectral widths as narrow as 1.5 meV. PL spectral widths of ~3 meV have been attained for the heavy hole exciton band, representing the narrowest value obtained for OMVPE material and an improvement of about 30% over our best previous results.

PHOTOPHYSICAL OVERVIEW OF EXCITATION ENERGY TRANSFER IN ORGANIC MOLECULAR ASSEMBLIES — A ROUTE TO STUDY BIO-MOLECULAR ARRAYS —

2001 ◽  
Vol 15 (28n30) ◽  
pp. 3857-3860 ◽  
Author(s):  
A. H. MATSUI ◽  
M. TAKESHIMA ◽  
K. MIZUNO ◽  
T. AOKI-MATSUMOTO
Keyword(s):  
Energy Transport ◽  
Free Exciton ◽  
Excitation Energy Transfer ◽  
Molecular Crystals ◽  
Chemical Species ◽  
Systematic Change ◽  
Bulk Crystals ◽  
Exciton Energy ◽  
Two Parameters ◽  
Constituent Molecule

Excitonic processes in organic molecular crystals are discussed in terms of two parameters, the crystal size and the constituent molecule size. From the luminescence and absorption spectra of a series of aromatic molecular crystals we find a systematic change in exciton energy transport as functions of the size of crystal and its constituent molecule size. Characteristic features of bulk crystals and microcrystallites are as follows. (1) In bulk crystals exciton energy transport depends on the constituent molecule size. When molecules are small, the exciton energy transport occurs by free excitons, but when molecules are large free exciton transport disappears because excitons get self-trapped. (2) In microcrystallites, exciton energy transport depends on the crystallite size. When the size is larger than a critical one, excitons travel as quantum mechanical waves but when the size is smaller than the critical one the exciton waves get confined within the crystallite. The results are independent of the chemical species of constituent molecules and thus applicable to novel molecular arrays such as biological molecular arrays.

scholarly journals Determination of the direct band-gap energy of InAlAs matched to InP by photoluminescence excitation spectroscopy

1997 ◽  
Vol 81 (10) ◽  
pp. 6916-6920 ◽  
Author(s):  
P. Roura ◽  
M. López-de Miguel ◽  
A. Cornet ◽  
J. R. Morante
Keyword(s):  
Band Gap ◽  
Band Gap Energy ◽  
Photoluminescence Excitation ◽  
Direct Band Gap ◽  
Gap Energy ◽  
Direct Band
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