Structural and Optical Characterization of CuxGaySe2Thin Films under Excitation with Above and Below Band Gap Laser Light

2002 ◽  
Vol 730 ◽  
Author(s):  
C. Xue ◽  
D. Papadimitriou ◽  
Y.S. Raptis ◽  
T. Riedle ◽  
N. Esser ◽  
...  
Keyword(s):  
Band Gap ◽  
Raman Spectra ◽  
Laser Light ◽  
Film Surface ◽  
Shallow Donor ◽  
Acceptor Pair ◽  
Donor And Acceptor ◽  
Donor Acceptor ◽  
Donor Acceptor Pair

AbstractCuxGaySe2MOCVD and PVD grown films were structurally and optically characterized by Raman, Micro-Raman and photoluminescence spectroscopy. Defect related photoluminescence excitation with wavelengths varying across the material band gap reveals: a) in Cu-rich CuGaSe2films, three band edge splitting due to the spin-orbit interaction and the crystal field, and donor-acceptor pair recombination between a shallow donor and two different acceptor levels, and b) in Ga-rich CuGaSe2films, donor-acceptor pair transitions between quasi-continua of donor and acceptor levels related to potential fluctuations. Raman spectra of CuxGaySe2films, excited by laser light near and below the material band gap, show intense modes at 197cm-1, 187cm-1, and 277cm-1, which can be used as indicators of crystallinity and Ga-content of the films. Polarization- and angular- dependent micro-Raman spectra of MOCVD CuGaSe2indicate that CuxSey-crystallites, dispersed on the surface of Cu-rich films, are grown oriented with their c-axis perpendicular to the film surface.

EL2-Induced Upconversion Luminescence In GaAs

1996 ◽  
Vol 442 ◽  
Author(s):  
V. Alex ◽  
T. Iino
Keyword(s):  
Band Gap ◽  
Upconversion Luminescence ◽  
Hot Electrons ◽  
Complete Disappearance ◽  
Acceptor Level ◽  
Acceptor Pair ◽  
Step Process ◽  
Regeneration Mechanism ◽  
Donor Acceptor ◽  
Donor Acceptor Pair

AbstractNear band gap luminescence in bulk-grown semi-insulating GaAs is excited in a two step process via the EL2 defect. While the conventionally excited photoluminescence of our samples is dominated by conduction band to acceptor transitions, the upconversion process selectively excites donor acceptor pair transitions. Illumination near the maximum of the EL2- photoquenching band at 1064 nm leads to a complete disappearance of the so called upconversion photoluminescence (UPL). Excitation with light of shorter wavelengths however only partially quenches the UPL. Excitation between 850nm and 900nm completely regenerates the UPL. The characteristic photorecovery transients of the UPL are described by the EL2 regeneration mechanism via the population of the acceptor level of the metastable EL2 by hot electrons. The recovery of the EL2 by simultaneous illumination with above and below band gap light enables the observation of UPL at wavelengths, where the EL2-defect would otherwise be rapidly quenched. Under these conditions we observe a remarkable increase of the UPL-efficiency.

scholarly journals Cyan-emitting and orange-emitting fluorescent proteins as a donor/acceptor pair for fluorescence resonance energy transfer

2004 ◽  
Vol 381 (1) ◽  
pp. 307-312 ◽  
Author(s):  
Satoshi KARASAWA ◽  
Toshio ARAKI ◽  
Takeharu NAGAI ◽  
Hideaki MIZUNO ◽  
Atsushi MIYAWAKI
Keyword(s):  
Energy Transfer ◽  
Fluorescence Resonance Energy Transfer ◽  
Fluorescent Proteins ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Acceptor Pair ◽  
Donor And Acceptor ◽  
Donor Acceptor ◽  
Donor Acceptor Pair ◽  
Fluorescence Resonance

GFP (green fluorescent protein)-based FRET (fluorescence resonance energy transfer) technology has facilitated the exploration of the spatio-temporal patterns of cellular signalling. While most studies have used cyan- and yellow-emitting FPs (fluorescent proteins) as FRET donors and acceptors respectively, this pair of proteins suffers from problems of pH-sensitivity and bleeding between channels. In the present paper, we demonstrate the use of an alternative additional donor/acceptor pair. We have cloned two genes encoding FPs from stony corals. We isolated a cyan-emitting FP from Acropara sp., whose tentacles exhibit cyan coloration. Similar to GFP from Renilla reniformis, the cyan FP forms a tight dimeric complex. We also discovered an orange-emitting FP from Fungia concinna. As the orange FP exists in a complex oligomeric structure, we converted this protein into a monomeric form through the introduction of three amino acid substitutions, recently reported to be effective for converting DsRed into a monomer (Clontech). We used the cyan FP and monomeric orange FP as a donor/acceptor pair to monitor the activity of caspase 3 during apoptosis. Due to the close spectral overlap of the donor emission and acceptor absorption (a large Förster distance), substantial pH-resistance of the donor fluorescence quantum yield and the acceptor absorbance, as well as good separation of the donor and acceptor signals, the new pair can be used for more effective quantitative FRET imaging.

Spectroscopic Characterization of Ion-Implanted GaN

2002 ◽  
Vol 743 ◽  
Author(s):  
L. Chen ◽  
B. J. Skromme
Keyword(s):  
Low Temperature ◽  
High Purity ◽  
Spectroscopic Characterization ◽  
Acceptor Pair ◽  
Donor Acceptor ◽  
Optical Activation ◽  
Donor Acceptor Pair ◽  
Low Temperature Photoluminescence ◽  
Do So

ABSTRACTWe investigate implantation of high purity HVPE GaN with Mg, Be, C, Zn, Cd, Ca, N, O, P, As, Ne, and Ar. After annealing at 1300 °C, the material is characterized using low temperature photoluminescence (PL). The Mg acceptors exhibit much better optical activation than Be, C, Zn, Cd, or Ca acceptors implanted and annealed under the same conditions. Acceptor-bound exciton peaks and well-resolved donor-acceptor pair bands are observed for both Mg and Zn. A broad peak centered near 2.78 eV is obtained for Cd, confirming that it is deeper than Zn. Isoelectronic As or P exhibit sharp no-phonon bound exciton lines at 2.952 and 3.200 eV, respectively. Defect-related bands centered at 2.2 and 2.35 eV are studied. Both Be and C strongly enhance the yellow (2.2 eV) PL band, but no other impurities do so, including O.

A novel complementary absorbing donor–acceptor pair in block copolymers based on single material organic photovoltaics

2014 ◽  
Vol 2 (9) ◽  
pp. 2993-2998 ◽  
Author(s):  
Sermet Koyuncu ◽  
Hsin-Wei Wang ◽  
Feng Liu ◽  
Kamil Bugra Toga ◽  
Weiyin Gu ◽  
...  
Keyword(s):  
Block Copolymer ◽  
Block Copolymers ◽  
Band Gap ◽  
Organic Photovoltaics ◽  
Acceptor Pair ◽  
Low Band Gap ◽  
Donor Acceptor ◽  
Donor Acceptor Pair ◽  
Single Material

We report on the first synthesis of a highly crystalline donor–acceptor low band gap block copolymer by using diketopyrrolopyrrole (DPP) as a low band gap block and perylenebisimide (PDI) as a strong acceptor block.

scholarly journals Characterization of donor–acceptor-pair emission in fluorescent 6H-SiC

2012 ◽  
Vol T148 ◽  
pp. 014003 ◽  
Author(s):  
Yiyu Ou ◽  
Valdas Jokubavicius ◽  
Margareta Linnarsson ◽  
Rositza Yakimova ◽  
Mikael Syväjärvi ◽  
...  
Keyword(s):  
Acceptor Pair ◽  
Donor Acceptor ◽  
Donor Acceptor Pair

Sharp line donor–acceptor pair luminescence in silicon

1981 ◽  
Vol 59 (6) ◽  
pp. 784-801 ◽  
Author(s):  
U. O. Ziemelis ◽  
R. R. Parsons
Keyword(s):  
Broad Band ◽  
High Energy ◽  
Near Band Edge ◽  
Acceptor Pair ◽  
Sharp Line ◽  
Line Structure ◽  
Donor And Acceptor ◽  
Decay Times ◽  
Donor Acceptor ◽  
Donor Acceptor Pair

New sharp line structure observed in the near-band-edge (1030 to 1135 meV) photoluminescence of Si(P, In) and Si(B, In) at temperatures ranging from 1.6 to 20 K, has been identified as due to radiative recombination of electrons bound to phosphorus donors with holes bound to indium acceptors. This is the first study of sharp line, donor–acceptor pair luminescence in silicon. Straightforward analysis, assuming only Coulomb and van der Waals interactions between otherwise isolated donor and acceptor centres indicates that recombination involving P and In centres separated by distances ranging from 7.7 to 20 Å is responsible for the observed sharp line structure. This structure is superimposed on the high energy shoulder of the broad band luminescence associated with recombination involving distant (average separation: 55 Å) P–In pairs. Transient measurements indicate decay times ranging from 70 to 100 μs for the most prominent sharp lines and an overall decay pattern consistent with that expected for donor–acceptor pair recombination.

High quantum efficiency of photoluminescence in GaN and ZnO

2005 ◽  
Vol 892 ◽  
Author(s):  
Michael A. Reshchikov ◽  
Xing Gu ◽  
Bill Nemeth ◽  
Jeff Nause ◽  
Hadis Morkoç
Keyword(s):  
Quantum Efficiency ◽  
Molecular Beam ◽  
Shallow Donor ◽  
Nonradiative Recombination ◽  
Acceptor Pair ◽  
High Quantum Efficiency ◽  
Donor Acceptor ◽  
Si Doped ◽  
Donor Acceptor Pair ◽  
Zno Crystal

AbstractThe quantum efficiency (QE) of photoluminescence (PL) has been estimated in GaN and ZnO samples. A Si-doped GaN layer grown by molecular beam epitaxy (MBE) exhibited the highest QE of about 90% at low temperatures. Recombination via the shallow donor-acceptor pair transitions dominated in this sample. In contrast, a bulk ZnO crystal with the QE of PL of about 85% contained almost no defect- or impurity-related PL signatures besides the emission attributed to free and bound excitons. The sources of radiative and nonradiative recombination in GaN and ZnO are discussed.

Optimizing Band Gap of Inorganic Halide Perovskites by Donor–Acceptor Pair Codoping

2020 ◽  
Vol 59 (9) ◽  
pp. 6053-6059
Author(s):  
Atef Iqbal ◽  
Zijuan Sun ◽  
Gang Wang ◽  
Jun Hu
Keyword(s):  
Band Gap ◽  
Acceptor Pair ◽  
Donor Acceptor ◽  
Halide Perovskites ◽  
Donor Acceptor Pair
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