Synthesis of formamidinium lead iodide perovskite bulk single crystal and its optical properties

2017 ◽  
Vol 31 (16-19) ◽  
pp. 1744066 ◽  
Author(s):  
Hongge Zheng ◽  
Junjie Duan ◽  
Jun Dai
Keyword(s):  
Single Crystal ◽  
Orthorhombic Phase ◽  
Near Band Edge ◽  
Cubic Phase ◽  
Band Edge Emission ◽  
Bulk Single Crystal ◽  
Lead Iodide ◽  
Temperature Dependent ◽  
Recombination Mechanism ◽  
Pl Spectra

Formamidinium lead iodide (FAPbI3) is a promising hybrid perovskite material for optoelectronic devices. We synthesized bulk single crystal FAPbI3 by a rapid solution crystallization method. X-ray diffraction (XRD) was performed to characterize the crystal structure. Temperature-dependent photoluminescence (PL) spectra of the bulk single crystal FAPbI3 were measured from 10 to 300 K to explain PL recombination mechanism. It shows that near band edge emission blueshifts with the temperature increasing from 10 to 120 K and from 140 K to room temperature, a sudden emission band redshift demonstrates near 140 K because of the phase transition from orthorhombic phase to cubic phase. From the temperature-dependent PL spectra, the temperature coefficients of the bandgap and thermal activation energies of FAPbI3 perovskite are fitted.

Effect of Remote Hydrogen Plasma Treatment on ZnO Single Crystal Surfaces

2002 ◽  
Vol 744 ◽  
Author(s):  
Yuri M. Strzhemechny ◽  
John Nemergut ◽  
Junjik Bae ◽  
David C. Look ◽  
Leonard J. Brillson
Keyword(s):  
Single Crystal ◽  
Plasma Treatment ◽  
Hydrogen Plasma ◽  
Free Exciton ◽  
Chemical Vapor Transport ◽  
Near Band Edge ◽  
Band Edge Emission ◽  
Exciton Transition ◽  
Near Surface ◽  
Pl Spectra

ABSTRACTWe have studied the effects of hydrogen plasma treatment on the defect characteristics in single crystal ZnO grown at Eagle-Picher by chemical vapor transport. Depth-dependent cathodoluminescence (CL) spectra, temperature-dependent (9–300 K) and excitation intensity-dependent photoluminescence (PL) spectra reveal significant changes resulting from unannealed exposure of n-type ZnO to a remote hydrogen plasma. Low temperature PL spectra show that this hydrogen exposure effectively suppresses the free-exciton transition and redistributes intensities in the bound-exciton line set and two-electron satellites with their phonon replicas. The resultant spectra after hydrogenation exhibit a new peak feature at 3.366 eV possibly related to a neutral donor bound exciton. A simple thermal analysis of the activation energy for the 3.366 eV line yields 5–10 meV. Hydrogenation also produces a violet 100 meV-wide peak centered at 3.16 eV. Remote plasma hydrogenation produces similar changes in room-temperature CL spectra: near-band edge emission intensity increases with hydrogenation. Furthermore, this new emission increases with proximity to the free ZnO surfaces, i.e., with decreasing the energy of the incident electron beam from 3.0 down to 0.5 keV. Subsequent annealing at 450 °C completely restores both the PL and CL spectra in the sub-band gap range. The appearance of a new bound-exciton feature at 3.366 eV with H plasma exposure, the near-surface nature of the spectral changes, and the reversibility of spectral features with annealing indicate a direct link between H indiffusion and appearance of a shallow donor.

Temperature-dependent Cl2/Ar plasma etching of bulk single-crystal ZnO

2003 ◽  
Vol 83 (15) ◽  
pp. 3105-3107 ◽  
Author(s):  
W. T. Lim ◽  
I. K. Baek ◽  
J. W. Lee ◽  
E. S. Lee ◽  
M. H. Jeon ◽  
...  
Keyword(s):  
Single Crystal ◽  
Plasma Etching ◽  
Bulk Single Crystal ◽  
Temperature Dependent ◽  
Ar Plasma

Temperature-dependent shifts of near band-edge emission and their second-order diffraction for ZnO nanorods

2012 ◽  
Vol 34 (11) ◽  
pp. 1917-1920 ◽  
Author(s):  
Jianguo Lv ◽  
Changlong Liu ◽  
Wanbing Gong ◽  
Zhenfa Zi ◽  
Xiaoshuang Chen ◽  
...  
Keyword(s):  
Zno Nanorods ◽  
Second Order ◽  
Band Edge ◽  
Near Band Edge Emission ◽  
Near Band Edge ◽  
Band Edge Emission ◽  
Temperature Dependent ◽  
Edge Emission ◽  
Order Diffraction

scholarly journals Nanocrystalline Oxides: CdS nanowires synthesized by solvothermal method

2014 ◽  
Vol 70 (a1) ◽  
pp. C1414-C1414
Author(s):  
Nomery Hadia ◽  
Santiago Garcia-Granda ◽  
Jose Garcia
Keyword(s):  
Metal Oxide ◽  
Single Crystal ◽  
Research Programme ◽  
Building Blocks ◽  
Mediterranean Area ◽  
Near Band Edge ◽  
Band Edge Emission ◽  
One Dimensional ◽  
Wide Range ◽  
Cds Nanowires

Recent advances in the field of nanotechnology produced an assortment of one-dimensional (1D) structures, such as nanowires and nanorods. These fascinating materials are the potential building blocks for a wide range of nanoscale electronics, optoelectronics, magnetoelectronics, or sensing devices [1]. Parallel to the success with group IV and groups III–V compounds semiconductor nanostructures, semiconducting metal oxide materials with wide band gaps are attracting attention [2-3]. The main aim of this communication is to report our results on the application of several new techniques, particularly the use of hydrothermal synthesis, to fabricate single crystal one-dimensional nanostructured materials, study their growth processes, understand the growth mechanisms and investigate their physical properties. A wide range of remarkable features are then presented, to cover a number of metal oxides, such as ZnO, Sb2O3, CdS, MgO, α-Fe2O3, or TiO2, describing their structures, optical, magnetic, mechanical and chemical sensing properties. These studies constitute the basis for developing versatile applications based on metal oxide 1D systems as well as highlighting the current progress in device development. To exemplify, the as-prepared CdS nanowires have average 28 nm in diameter and length up to several micrometres. The direct band gap of the CdS nanowires is 2.56 eV calculated by the UV-vis absorption spectra. The PL spectrum has two distinct emission bands at 502 nm and 695 nm, which are associated with the near-band-edge emission and defect emission, respectively. These synthesized single-crystal CdS nanowires have a high potential in the optoelectronic applications of nanolasers, solar cells, lighting-emitting diodes or photodetectors. Acknowledgments: Erasmus Mundus MEDASTAR (Mediterranean Area for Science, Technology and Research) Programme, 2011–4051/002–001-EMA2, Spanish MINECO (MAT2010-15094, Factoría de Cristalización – Consolider Ingenio 2010) and ERDF.

Photoluminescence of ZnO Nanocrystals Embedded in BaF2 Matrices by Magnetron Sputtering

2008 ◽  
Vol 8 (3) ◽  
pp. 1160-1164
Author(s):  
C. H. Zang ◽  
Y. C. Liu ◽  
R. Mu ◽  
D. X. Zhao ◽  
J. Y. Zhang ◽  
...  
Keyword(s):  
Magnetron Sputtering ◽  
Raman Scattering ◽  
Free Exciton ◽  
Wide Band ◽  
Zno Films ◽  
Near Band Edge ◽  
Band Edge Emission ◽  
Ultraviolet Emission ◽  
Pl Spectra ◽  
Zno Nanocrystals

This paper describes ZnO nanocrystals embedded in BaF2 matrices by the magnetron sputtering method in an attempt to use fluoride as a shell layer to embed ZnO nanocrystals core. BaF2 is a wide-band gap material, and can confine carriers in the ZnO films. As a result, the exciton emission intensity should be enhanced. The sample was annealed at 773 K, and X-ray diffraction (XRD) results showed that ZnO nanocrystals with wurtzite structure were embedded in BaF2 matrices. Raman-scattering spectra also confirmed the formation of ZnO nanoparticles. Abnormal longitudinal-optical (LO) phonon-dominant multiphonon Raman scattering was observed in the sample. Room-temperature photoluminescence (PL) spectra showed an ultraviolet emission peak at 374 nm. The origin of the ultraviolet emission is discussed here with the help of temperature-dependent PL spectra. The ultraviolet emission band was a mixture of free exciton and bound exciton recombination observed in the low temperature PL spectra (at 77 K). Abnormal temperature dependence of ultraviolet near-band-edge emission-integrated intensity of the sample was observed. The band tail state was observed in the absorption spectra, illustrating that the impurity-related defects were caused by the shell of the BaF2 grain layer. For comparison, ZnO films on BaF2 substrates were also fabricated by the magnetron sputtering method, and the same measurement methods were used.

Variable-temperature single-crystal X-ray diffraction study of tetragonal and cubic perovskite-type barium titanate phases

2016 ◽  
Vol 72 (1) ◽  
pp. 151-159 ◽  
Author(s):  
Tomotaka Nakatani ◽  
Akira Yoshiasa ◽  
Akihiko Nakatsuka ◽  
Tatsuya Hiratoko ◽  
Tsutomu Mashimo ◽  
...  
Keyword(s):  
Single Crystal ◽  
Diffraction Study ◽  
Variable Temperature ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
M Phase ◽  
The Mean ◽  
Perovskite Type

A variable-temperature single-crystal X-ray diffraction study of a synthetic BaTiO3perovskite has been performed over the temperature range 298–778 K. A transition from a tetragonal (P4mm) to a cubic (Pm \overline 3 m) phase has been revealed near 413 K. In the non-centrosymmetricP4mmsymmetry group, both Ti and O atoms are displaced along thec-axis in opposite directions with regard to the Ba position fixed at the origin, so that Ti4+and Ba2+cations occupy off-center positions in the TiO6and BaO12polyhedra, respectively. Smooth temperature-dependent changes of the atomic coordinates become discontinuous with the phase transition. Our observations imply that the cations remain off-center even in the high-temperature cubic phase. The temperature dependence of the mean-square displacements of Ti in the cubic phase includes a significant static component which means that Ti atoms are statistically distributed in the off-center positions.

The compositional and optical characterizations of InGaAsN alloy semiconductor grown by MOVPE

2002 ◽  
Vol 744 ◽  
Author(s):  
Sakuntam Sanorpim ◽  
Fumihiro Nakajima ◽  
Ryuji Katayama ◽  
Kentaro Onabe ◽  
Yashihiro Shiraki
Keyword(s):  
Room Temperature ◽  
Excitation Power ◽  
Band Edge ◽  
Near Band Edge Emission ◽  
Near Band Edge ◽  
Band Edge Emission ◽  
Optical Investigation ◽  
Edge Emission ◽  
Alloy Films ◽  
Pl Spectra

ABSTRACTWe report on the compositional and optical investigation of InGaAs(N) alloy films grown on GaAs (001) substrates by low-pressure (60 Torr) metalorganic vapor phase epitaxy (MOVPE). The alloy films with the room-temperature photoreflactance (PR) signal (Eo transition) wavelength range of 0.98–1.36 m have been grown. The variation in PL characteristics of the InGaAs(N) alloy films has been investigated as a function of alloy composition, excitation power and temperature. At low temperatures (T<100K), the PL spectra with several sub-peaks include localization emission as well as near-band-edge emission. On the other hand, the room-temperature PL properties for InxGa1-xAs1-yNy (x = 10.5% and 17.0% and y < 2%) are excellent with a single near-band-edge emission peak corresponding to their own Eo transition. The evolution of PL spectra with excitation power and temperature led to an insight into the nature of the near-band-edge states. The temperature dependence of integrated PL intensity indicates the presence of a large density of non-radiative recombination centers, showing a behavior characterized by two activation energies. Our results suggest that the origin of localization in InGaAsN alloy films is the alloy inhomogeneities of both In and N, which may results in the characteristic carrier dynamics.

scholarly journals Annealing Behavior of The Photoluminescence Lines in CdTe and Znx Cd1−x Te Single Crystals

1989 ◽  
Vol 161 ◽  
Author(s):  
J. Gonzalez-Hernandez ◽  
A. Reyes-Mena ◽  
Elias Lopez-Cruz ◽  
D.D. Allred ◽  
Worth P. Allred
Keyword(s):  
Single Crystals ◽  
Mixed Crystals ◽  
Band Edge ◽  
Near Band Edge ◽  
Band Edge Emission ◽  
Photoluminescence Spectra ◽  
Edge Emission ◽  
Annealing Behavior ◽  
Pl Spectra ◽  
Compositional Range

ABSTRACTThe main lines in the photoluminescence spectra of Zn1Cd1−xTe single crystals grown by a modified Bridgman method in the compositional range of 0 ≤ X ≤ 0.25 have been identified. All crystals show only near-band-edge emission. To assist in the identification, various samples with different compositions were annealed under a Cd atmosphere. In the pure crystals, the prominent (A°,X) bound exciton line, as well as the doublet at longer wavelengths, disappear after the annealing. In contrast, the treatments do not change significantly the PL spectra of the mixed crystals.

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