Electronic Properties and Their Relations to Optical Properties in Rare Earth Doped III-V Semiconductors

1993 ◽  
Vol 301 ◽  
Author(s):  
Akihito Taguchi ◽  
Kenichiro Takahei ◽  
Jyoji Nakata
Keyword(s):  
Optical Properties ◽  
Rare Earth ◽  
Chemical Vapor ◽  
Luminescence Spectra ◽  
Energy Transfer Mechanism ◽  
Relaxation Energy ◽  
Rutherford Back Scattering ◽  
Measurement Results ◽  
Electron Hole Pair ◽  
Er Doped

ABSTRACTWe discuss the energy transfer mechanism between rare-earth 4f-shells and III-V semiconductor hosts. For Yb-doped InP, we have proposed an excitation and relaxation model, which explains experimental results for the electronic and optical properties. The Yb 4f-shell is excited by a recombination of an electron and a hole at an electron trap formed by Yb, which is located near the bottom of the conduction band of InP. At high temperatures, the relaxation energy of the Yb 4f-shell is back transferred as a host electron-hole pair, resulting in Yb luminescence quenching. We have found that Er-doped GaAs samples grown by metalorganic chemical vapor deposition contain as much C as Er. Rutherford back scattering and electronic property measurement results suggested that most of the Er atoms form complexes with C atoms, and these complexes are not electrically active. Such samples showed complicated Er 4f-shell luminescence spectra. To obtain a simple Er luminescence spectrum with a high peak intensity, O was intentionally doped with Er. Er-O complexes seemed to be formed in GaAs and these are responsible for simple and strong 4f-shell luminescence.

scholarly journals Enhanced luminescence of rare-earth Tb (III) obtained by mixing of Gd (III) in a fumarate complex and intra-molecular energy transfer

2015 ◽  
Vol 33 (4) ◽  
pp. 685-691 ◽  
Author(s):  
M.D. Shah ◽  
B. Want
Keyword(s):  
Optical Properties ◽  
Energy Transfer ◽  
Rare Earth ◽  
Green Emission ◽  
Lanthanide Ions ◽  
Luminescence Spectra ◽  
Mixed Complex ◽  
Energy Transfer Mechanism ◽  
Terbium Complex ◽  
Diffusion Technique

AbstractTrivalent lanthanide ions display fascinating optical properties. Therefore, the rare-earth complexes of terbium fumarate heptahydrate and GdTb fumarate heptahydrate were grown by using a single gel diffusion technique. The crystals were characterized by different physicochemical techniques of characterization. UV-Vis and photoluminescence spectrophotometric experiments were carried out to study the optical properties of the grown crystals. Under various excitations (339 nm, 350 nm or 368 nm) the terbium fumarate complex emitted characteristic (4f-4f) green emission of Tb3+ (5D4-7FJ, J = 6, 5, 4 and 3, respectively). Luminescence spectra showed that Gd3+ ions in the mixed complex have not affected the luminescence emission peak positions, but remarkably increased the luminescent intensities of the terbium complex. The energy-transfer mechanism between the ligand and the central Tb3+ ions and from the Gd3+ to the Tb3+ was discussed.

scholarly journals Investigations on the Optical Properties of InGaN/GaN Multiple Quantum Wells with Varying GaN Cap Layer Thickness

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Xiaowei Wang ◽  
Feng Liang ◽  
Degang Zhao ◽  
Zongshun Liu ◽  
Jianjun Zhu ◽  
...  
Keyword(s):  
Optical Properties ◽  
Quantum Wells ◽  
Layer Thickness ◽  
Stark Effect ◽  
Chemical Vapor ◽  
Multiple Quantum ◽  
Three Samples ◽  
Measurement Results ◽  
Cap Layer ◽  
The Difference

Abstract Three InGaN/GaN MQWs samples with varying GaN cap layer thickness were grown by metalorganic chemical vapor deposition (MOCVD) to investigate the optical properties. We found that a thicker cap layer is more effective in preventing the evaporation of the In composition in the InGaN quantum well layer. Furthermore, the quantum-confined Stark effect (QCSE) is enhanced with increasing the thickness of GaN cap layer. In addition, compared with the electroluminescence measurement results, we focus on the difference of localization states and defects in three samples induced by various cap thickness to explain the anomalies in room temperature photoluminescence measurements. We found that too thin GaN cap layer will exacerbates the inhomogeneity of localization states in InGaN QW layer, and too thick GaN cap layer will generate more defects in GaN cap layer.

Crystal structure and optical properties of erbium- and neodymium-doped zirconia nanoparticles

2010 ◽  
Vol 25 (3) ◽  
pp. 500-509 ◽  
Author(s):  
Morgana M. Trexler ◽  
Dajie Zhang ◽  
Lisa Kelly ◽  
Jennifer Sample
Keyword(s):  
Crystal Structure ◽  
Optical Properties ◽  
Monoclinic Phase ◽  
Near Infrared ◽  
Annealing Temperature ◽  
Dopant Concentration ◽  
Luminescence Spectra ◽  
Novel Method ◽  
Er Doped ◽  
Zirconia Nanoparticles

We report the synthesis, characterization, and optical properties of high-temperature stable lanthanide-doped luminescent zirconia nanoparticles via a novel method using carbon black as template. Dopant concentrations were varied from 1 to 5% of Er3+ or Nd3+ and annealing temperatures were varied from 650 to 1100 °C. The effects of the dopant concentration on crystal structure and emission properties were evaluated using x-ray powder diffraction and fluorescence spectroscopy, respectively. The lanthanide cations were found to stabilize the tetragonal phase of zirconia over the monoclinic phase as dopant concentration was increased to 5%. Increasing the annealing temperature to 1100 °C had the opposite effect and was found to stabilize the monoclinic phase of zirconia. The luminescence intensity of the Nd-doped zirconia was enhanced by two orders of magnitude over the undoped or Er-doped zirconia. In all cases, the luminescence spectra revealed increasing intensity with increasing annealing temperature. Zirconia luminescence at near-infrared wavelengths is likely caused by oxygen vacancies. This work demonstrates that the spectral signatures of fluorescent zirconia nanoparticles can be modified with small lanthanide dopant concentration. These particles will have utility in fluorescent sensors and tags, as well as new in refractory materials.

Impact of the Growth Polar Direction on the Optical Properties of Gan Films Grown by Metalorganic Vapor Phase Epitaxy

2000 ◽  
Vol 639 ◽  
Author(s):  
A. Setoguchi ◽  
K. Yoshimura ◽  
M. Sumiya ◽  
A. Uedono ◽  
S. F. Chichibu
Keyword(s):  
Optical Properties ◽  
Vapor Phase ◽  
Secondary Ion Mass Spectrometry ◽  
Stokes Shift ◽  
Chemical Vapor ◽  
Vapor Phase Epitaxy ◽  
Luminescence Spectra ◽  
Broad Emission Band ◽  
Polar Direction ◽  
The Difference

ABSTRACTThe growth polar direction during metalorganic chemical vapor phase epitaxy of wurtzite GaN films was shown to affect the optical properties in terms of impurity and vacancy-type defect incorporation during the growth. The GaN film grown towards the Ga- face (0001) (+c polarity) exhibited clear excitonic features in its optical absorption and luminescence spectra up to room temperature. Conversely, the film with the N-face (000-1) (-c polarity) exhibited a broad emission band, which is located in the broadened absorption tail. The Stokes shift remained even at 300 K. The difference between the two was explained in terms of the presence of impurity-induced band tail states in –c GaN due to increased impurity density and enhanced incorporation of large volume vacancy-type defects, which were confirmed by secondary ion mass spectrometry [Sumiya et al., Appl. Phys. Lett. 76, 2098 (2000)] and monoenergetic slow positron annihilation technique.

scholarly journals Novel Multicomponent Titanate-Germanate Glasses: Synthesis, Structure, Properties, Transition Metal, and Rare Earth Doping

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4422
Author(s):  
Wojciech A. Pisarski ◽  
Karolina Kowalska ◽  
Marta Kuwik ◽  
Justyna Polak ◽  
Ewa Pietrasik ◽  
...  
Keyword(s):  
Optical Properties ◽  
Rare Earth ◽  
Transition Metal ◽  
Rare Earth Ions ◽  
Luminescence Spectroscopy ◽  
Luminescence Spectra ◽  
Rare Earth Doping ◽  
Stability Parameters ◽  
Dsc Measurements ◽  
Germanate Glasses

Novel multicomponent titanate-germanate glasses singly doped with transition metal (Cr3+) and rare earth ions (Eu3+) were synthesized and the glass transition temperatures and thermal stability parameters were determined using DSC measurements. X-ray diffraction analysis confirmed fully amorphous nature of the received samples. Their structural and optical properties were compared with germanate glasses without TiO2. Correlation between local structure and optical properties in titanate-germanate glasses is well evidenced by FT-IR, Raman, EPR, and luminescence spectroscopy. In particular, luminescence spectra and their decays are examined for glass samples, where GeO2 was partially substituted by TiO2.

scholarly journals Optical Properties of Lanthanide -Containing Halide-Modified Zinc Tellurite Glasses

1996 ◽  
Vol 453 ◽  
Author(s):  
D. L. Sidebottom ◽  
Michael A. Hruschka ◽  
B. G. Potter ◽  
Richard K. Brow ◽  
James J. Hudgens
Keyword(s):  
Optical Properties ◽  
Rare Earth ◽  
Optical Absorption ◽  
Tellurite Glasses ◽  
Oxide Glasses ◽  
Optical Absorption Spectra ◽  
Rare Earth Ion ◽  
Tellurium Oxide ◽  
Vibrational Characteristics ◽  
Er Doped

AbstractAs part of an ongoing investigation to characterize the properties and structure of zinc halide-tellurium oxide glasses, we report preliminary measurements of the optical properties of several Nd- and Er-doped tellurites. Measurements include florescence lifetimes and estimates of the theoretical radiative lifetimes (as obtained by traditional Judd-Ofelt analysis of optical absorption spectra) as well as phonon sideband studies sensitive to vibrational characteristics near the rare earth ion. The response of these optical features to the substitution of alternative halides is examined.

scholarly journals Influence of a Thermal Pad on Selected Parameters of Power LEDs

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3732
Author(s):  
Krzysztof Górecki ◽  
Przemysław Ptak ◽  
Tomasz Torzewicz ◽  
Marcin Janicki
Keyword(s):  
Optical Properties ◽  
Thermal Resistance ◽  
Optical Power ◽  
Junction Temperature ◽  
Operating Parameters ◽  
Cold Plate ◽  
Optical Efficiency ◽  
Forward Current ◽  
Measurement Results ◽  
Set Up

This paper is devoted to the analysis of the influence of thermal pads on electric, optical, and thermal parameters of power LEDs. Measurements of parameters, such as thermal resistance, optical efficiency, and optical power, were performed for selected types of power LEDs operating with a thermal pad and without it at different values of the diode forward current and temperature of the cold plate. First, the measurement set-up used in the paper is described in detail. Then, the measurement results obtained for both considered manners of power LED assembly are compared. Some characteristics that illustrate the influence of forward current and temperature of the cold plate on electric, thermal, and optical properties of the tested devices are presented and discussed. It is shown that the use of the thermal pad makes it possible to achieve more advantageous values of operating parameters of the considered semiconductor devices at lower values of their junction temperature, which guarantees an increase in their lifetime.

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