Current Search: Photoluminescence (x)
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- Title
- Photoluminescence study of zinc(1-x)manganese(x)sulfur.
- Creator
- Moreno, Miguel Angel, Florida Atlantic University, Medina, Fernando D.
- Abstract/Description
-
Zinc(1-x)manganese(x)sulfur is a ternary semiconductor compound which belongs to the family of diluted magnetic semiconductors (DMS). It has two crystalline phases: cubic for x
Show moreZinc(1-x)manganese(x)sulfur is a ternary semiconductor compound which belongs to the family of diluted magnetic semiconductors (DMS). It has two crystalline phases: cubic for x < 0.10, and hexagonal for 0.10 < x < 0.50. Its energy gap is temperature and x dependent. The gap, ranging from 3.7 to 3.8 eV, is the largest of the DMS. These properties allow studies of the energy levels of the Mn^2+ ions in ZnS and their internal or ion-to-band transitions, by using photoluminescence. Samples with x = 0.01-0.50 were excited with the 5145A line of an Ar+ laser. The spectra, taken at temperatures between 10 and 300K, showed three bands: a band peaking at 2.12 eV was related to the 4T1 to 6A1 internal transition; a band peaking at 1.95-2.10 eV (depending on T) was related to the 4T1 to Gamma 1 5 ion-to-band transition; the origin of the third band, peaking at 1.65 eV, was discussed. A partial fourth band in the IR region was detected. The position of the 6A1 state with respect to the valence band was established.
Show less - Date Issued
- 1989
- PURL
- http://purl.flvc.org/fcla/dt/14560
- Subject Headings
- Diluted magnetic semiconductors, Photoluminescence
- Format
- Document (PDF)
- Title
- Photoluminescence characterization of aluminum gallium arsenide/gallium arsenide quantum well interfacial quality.
- Creator
- Wan, Zhong, Florida Atlantic University, Liu, Da Wei
- Abstract/Description
-
A photoluminescence (PL) study of Al(x)Ga(1-x)As/GaAs quantum wells (QWs) was undertaken at low temperature by using the HeNe laser. The temperature dependence of heavy hole exciton peak energies indicated that the PL signals are contributed by the recombination of excitons bound to interface defects at low temperature and the recombination of free excitons at high temperature. The temperature dependence of the PL profile of a single QW sample with growth interruption at the interfaces was...
Show moreA photoluminescence (PL) study of Al(x)Ga(1-x)As/GaAs quantum wells (QWs) was undertaken at low temperature by using the HeNe laser. The temperature dependence of heavy hole exciton peak energies indicated that the PL signals are contributed by the recombination of excitons bound to interface defects at low temperature and the recombination of free excitons at high temperature. The temperature dependence of the PL profile of a single QW sample with growth interruption at the interfaces was successfully interpreted by the enlarged monolayer fluctuation. The linewidth of low temperature PL peaks was used to characterize the interfacial quality of QWs. The quality improvement of single QWs by tilting (001) substrate 4 degrees toward (111) Ga direction was observed.
Show less - Date Issued
- 1992
- PURL
- http://purl.flvc.org/fcla/dt/14835
- Subject Headings
- Quantum wells, Photoluminescence
- Format
- Document (PDF)
- Title
- Bioluminescence and the Pelagic Visual Environment.
- Creator
- Widder, Edith A., Harbor Branch Oceanographic Institute
- Date Issued
- 2002
- PURL
- http://purl.flvc.org/FCLA/DT/2796514
- Subject Headings
- Luminescent probes, Fluorescence microscopy, Cytofluorometry, Photoluminescence, Pelagiidae
- Format
- Document (PDF)
- Title
- Photoluminescence analysis of zinc(1-x) manganese(x) selenium.
- Creator
- Xue, Jun, Florida Atlantic University, Medina, Fernando D.
- Abstract/Description
-
Zn1-x is a ternary alloy belonging to a class of materials known as Diluted Magnetic Semiconductors (DMS's). Single-crystal samples of this material possesses a cubic (zinc-blende) structure for x 300 K. Three emission bands are detected and are named the YEL (centered ~2.12 eV), ORA (centered 1.91 --> 1.98 eV) and IR bands. The shift of the YEL band is observed and related to the d-d interaction of the Mn^+2 ions and to thermal lattice expansion. The electron-phonon interaction is used to...
Show moreZn1-x is a ternary alloy belonging to a class of materials known as Diluted Magnetic Semiconductors (DMS's). Single-crystal samples of this material possesses a cubic (zinc-blende) structure for x<0.30 and a hexagonal (wurtzite) structure for 0.30300 K. Three emission bands are detected and are named the YEL (centered ~2.12 eV), ORA (centered 1.91 --> 1.98 eV) and IR bands. The shift of the YEL band is observed and related to the d-d interaction of the Mn^+2 ions and to thermal lattice expansion. The electron-phonon interaction is used to explain the broadening of the YEL band. A model is proposed to explain the existence of the ORA band and the shift of its energy with temperature and Mn concentration. This model for the first time provides a detailed explanation of the anomalous behavior of the energy gap of this material for low Mn concentrations.
Show less - Date Issued
- 1997
- PURL
- http://purl.flvc.org/fcla/dt/15388
- Subject Headings
- Diluted magnetic semiconductors--Analysis, Photoluminescence
- Format
- Document (PDF)
- Title
- Spectroscopic studies of zinc(1-x) manganese(x) sulfur.
- Creator
- Chen, Xiaoming., Florida Atlantic University, Medina, Fernando D.
- Abstract/Description
-
The optical properties of the diluted magnetic semiconductor Zn1-x MnxS have been studied by using photoluminescence emission, lifetime and excitation spectroscopies. In photoluminescence spectroscopy three bands were found peaking at 585 nm (yellow band), 650 nm (orange band) and 750 nm (red band). For the yellow and red bands the peak position changes little with Mn concentration. For the orange band the peak energy decreases with increasing Mn concentration. The lifetimes of the yellow,...
Show moreThe optical properties of the diluted magnetic semiconductor Zn1-x MnxS have been studied by using photoluminescence emission, lifetime and excitation spectroscopies. In photoluminescence spectroscopy three bands were found peaking at 585 nm (yellow band), 650 nm (orange band) and 750 nm (red band). For the yellow and red bands the peak position changes little with Mn concentration. For the orange band the peak energy decreases with increasing Mn concentration. The lifetimes of the yellow, orange and red bands were found to be about 70, 50 and 7 mus. The results of the lifetime measurements support the assumption that there is energy transfer from the yellow to the red band through radiationless transitions. In the excitation spectroscopy of the yellow band four peaks were found peaking near 526, 487, 461 and 426 nm. These four bands have been ascribed to transitions from the four lowest excited states of Mn ++ to the ground state. (Abstract shortened with permission of author.)
Show less - Date Issued
- 1992
- PURL
- http://purl.flvc.org/fcla/dt/14790
- Subject Headings
- Diluted magnetic semiconductors, Photoluminescence, Spectrum analysis
- Format
- Document (PDF)