Energy-Back-Transfer Process in Rare-Earth Doped AlGaN

2005 ◽  
Vol 866 ◽  
Author(s):  
A. Wakahara ◽  
T. Fujiwara ◽  
H. Okada ◽  
A. Yoshida ◽  
T. Ohshima ◽  
...  
Keyword(s):  
Rare Earth ◽  
Temperature Dependence ◽  
Transfer Process ◽  
Decay Time ◽  
Thermal Quenching ◽  
Rare Earth Ions ◽  
Transfer Model ◽  
Time Resolved ◽  
Peak Energy ◽  
Back Transfer

AbstractTemperature dependence of time-resolved photoluminescence (PL) properties for rare-earth ions (REIs: Eu, Tb, and Er) implanted AlxGa1-xN (x=0∼1) is investigated. Thermal quenching for RE-related PL becomes small when increasing the Al contents. The PL decay time of REIs used in the present work becomes shorter when increasing the temperature and/or PL peak energy. The temperature dependence of PL intensity and the decay time are analysed by assuming phonon assisted energy-back-transfer model, in which the energy in REIs escape to trap levels. From the results, the improvement of PL properties can be well explained by the model, in which the activation energy for energy-back-transfer process is increased as increasing the Al contents.

ENERGY-TRANSFER PROCESS IN RARE-EARTH-ION DOPED SrTiO3

2001 ◽  
Vol 15 (28n30) ◽  
pp. 3924-3927 ◽  
Author(s):  
SHINJI OKAMOTO ◽  
SHOSAKU TANAKA ◽  
HAJIME YAMAMOTO
Keyword(s):  
Energy Transfer ◽  
Rare Earth ◽  
Temperature Dependence ◽  
Oscillator Strength ◽  
Transfer Process ◽  
Emission Intensity ◽  
Energy Transfer Process ◽  
Rare Earth Ions ◽  
Rare Earth Ion ◽  
Pl Spectra

Enhancement of emission intensity of rare-earth-ion doped SrTiO 3 by Al addition has been investigated. In the case of Pr 3+ and Tb 3+, addition of 23-mol% Al intensifies emission by more than 200 times. In contrast, the addition of 20 mol% Al intensifies emission at most by three times in the case of other rare-earth ions. The temperature dependence of PL spectra shows that the energy transfer from carriers to Pr 3+ or Tb 3+ ions is much more efficient than that to other rare-earth ions in SrTiO 3. It can be speculated that the energy transfer in SrTiO 3: Pr 3 or Tb 3+ occurs from carriers to Pr 3+ or Tb 3+ ion via 4f-5d transitions, which are much higher in oscillator strength than 4f-4f transitions.

scholarly journals Dynamics of Anomalous Temperature-Induced Emission Shift in MOCVD-grown (Al, In)GaN Thin Films

2000 ◽  
Vol 5 (S1) ◽  
pp. 796-802 ◽  
Author(s):  
Yong-Hoon Cho ◽  
G. H. Gainer ◽  
J. B. Lam ◽  
J. J. Song ◽  
W Yang ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Stokes Shift ◽  
Energy Shift ◽  
Peak Position ◽  
Time Resolved ◽  
Temperature Range ◽  
Al Content ◽  
Peak Energy ◽  
Emission Behavior ◽  
Pl Intensity

We present a comprehensive study of the optical characteristics of (Al, In)GaN epilayers measured by photoluminescence (PL), integrated PL intensity, and time-resolved PL spectroscopy. For not only InGaN, but also AlGaN epilayers with large Al content, we observed an anomalous PL temperature dependence: (i) an “S-shaped” PL peak energy shift (decrease-increase-decrease) and (ii) an “inverted S-shaped” full width at half maximum (FWHM) change (increase-decrease-increase) with increasing temperature. Based on time-resolved PL, the S shape (inverted S shape) of the PL peak position (FWHM) as a function of temperature, and the much smaller PL intensity decrease in the temperature range showing the anomalous emission behavior, we conclude that strong localization of carriers occurs in InGaN and even in AlGaN with rather high Al content. We observed that the following increase with increasing Al content in AlGaN epilayers: (i) a Stokes shift between the PL peak energy and the absorption edge, (ii) a redshift of the emission with decay time, (iii) the deviations of the PL peak energy, FWHM, and PL intensity from their typical temperature dependence, and (iv) the corresponding temperature range of the anomalous emission behavior. This indicates that the band-gap fluctuation responsible for these characteristics is due to energy tail states caused by non-random inhomogeneous alloy potential variations enhanced with increasing Al content.

Application of Nitride and Oxynitride Compounds to Various Phosphors for White LED

2008 ◽  
Vol 403 ◽  
pp. 15-18 ◽  
Author(s):  
Kyota Uheda
Keyword(s):  
Rare Earth ◽  
Thermal Quenching ◽  
Rare Earth Ions ◽  
White Led ◽  
Green Phosphor ◽  
Strong Emission ◽  
Red Phosphor ◽  
Blue Phosphor ◽  
Uv Led ◽  
Intense Emission

Multiternary nitride and oxynitride compounds doped with rare earth ions, such as Eu2+ and Ce3+ have been enthusiastically applied as various phosphors to white LED. New red and green phosphors, CaAlSiN3:Eu and Ba3Si6O12N2:Eu, have been successfully synthesized, recently. The red phosphor has intense emission around 650 nm under two different irradiations at 405 and 455 nm from blue- and near UV-LED chips, respectively; while strong emission is observed around 520 nm from the green phosphor. Both phosphors also show small thermal quenching over the temperatures up to 150 °C. In addition, both LaSi3N5:Ce and La3Si8O4N11:Ce in lanthanum silicon nitride and oxynitride were examined as candidates for a blue phosphor in white LED with near UV-LED chip.

scholarly journals Влияние мультиплетных уровней Sm-=SUP=-3+-=/SUP=- и Eu-=SUP=-3+-=/SUP=- на теплоемкость мультиферроика BiFeO-=SUB=-3-=/SUB=-

2021 ◽  
Vol 63 (6) ◽  
pp. 763
Author(s):  
Р.Г. Митаров ◽  
С.Н. Каллаев ◽  
З.М. Омаров ◽  
О.М. Назарова ◽  
Л.А. Резниченко
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Rare Earth ◽  
Specific Heat ◽  
Temperature Dependence ◽  
Bismuth Ferrite ◽  
Rare Earth Ions ◽  
Phonon Thermal Conductivity ◽  
Additional Heat ◽  
Schottky Effect

The temperature dependence of the heat capacity of the multiferroics BiFeO3, Bi0.90Sm0.10FeO3, and Bi0.90Eu0.10FeO3 has been studied. It was found that the substitution of europium and samarium ions for bismuth ions in bismuth ferrite leads to the appearance of an additional heat capacity component due to transitions of 4f - electrons of rare earth ions to higher levels of the multiplet. A connection is established between the decrease in phonon thermal conductivity and the Schottky effect for the specific heat.

Elimination of the Intraion Spectral Interference between the 5D0 and 5D1 Emission Bands of Eu3+ in EuP5O14 by Using the Time-Resolved Spectroscopy Technique

1985 ◽  
Vol 39 (3) ◽  
pp. 546-549
Author(s):  
I. Laulicht ◽  
I. Peer
Keyword(s):  
Rare Earth ◽  
Spectral Interference ◽  
Rare Earth Ions ◽  
Emission Lines ◽  
Spectroscopy Technique ◽  
Time Resolved ◽  
Time Resolved Spectroscopy ◽  
Fluorescence Studies

The advantage of the time-resolved spectroscopy technique for reducing the spectral interference between the 5D0 and 5D1 emission lines of Eu3+ ions in EuP5O14 crystals is explained in detail. It is shown that this technique may be very helpful for rare earth ions fluorescence studies in general whenever a group of two or more neighboring levels emit photons to the same lower levels but their lifetimes are different. The wavelengths of many new lines of the 5D0 → 7Fj (j = 3–6) emission bands of Eu3+ in EuP5O14 are measured by this technique.

Sign in / Sign up

Export Citation Format

Share Document