Extensions of Handel’s 1/<i>f</i>-noise equations and their semiclassical theory

Ziel, A. van der; Rheenen, Arthur D. van; Birbas, A. N.

doi:10.1103/physrevb.40.1806

Cited by 15 publications

(5 citation statements)

References 8 publications

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“…This result is much lower than the values compared to the other phosphors. [18][19][20] As can be seen from Table I, the diffusion constant changes gradually, increasing with Eu 3ϩ concentration. At these high concentrations the energy transfer is dominated by the nearest neighbor Eu 3ϩ -Eu 3ϩ transfer time.…”

Section: ͓8͔mentioning

confidence: 82%

Photoluminescence Properties of Eu[sup 3+]-Activated Y[sub 2]GeO[sub 5] Phosphors

Park¹,

Ahn²,

Lim³

et al. 2003

J. Electrochem. Soc.

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The luminescence and energy transfer properties of Eu 3ϩ in Y 2 GeO 5 have been investigated. The critical concentration at which the concentration quenching occurred under UV excitation were x ϭ 0.4 in (Y 1Ϫx Eu x ) 2 GeO 5 . To investigate the distinction of photoluminescence behavior of two transitions ͑i.e., 5 D 0 → 7 F 1 and 5 D 0 → 7 F 2 transition͒ for the Eu 3ϩ ion, the decay curves for both 5 D 0 → 7 F 1 and 5 D 0 → 7 F 2 transition have been analyzed. Furthermore the energy migration process of this sample was investigated using Yokota and Tanimoto's formula based on diffusion limited quenching.The (Y 2 O 3 -GeO 2 ) phosphor has recently found an oxide phosphor as a phosphor material for the emitting layer of thin-film electroluminescent ͑TFEL͒ devices. 1,2 Because of high luminous efficiency, (Y 2 O 3 -GeO 2 ):Mn phosphor has been studied as a promising material for TFEL displays as well as plasma display panels and field emission displays. 3 In this view, it seems interesting to study the luminescence of some rare earths in the (Y 2 O 3 -GeO 2 ). Among them, the Eu 3ϩ ion has attracted great attraction due to the application as red phosphors. [4][5][6][7] In this work, we prepared Eu 3ϩ -activated Y 2 GeO 5 phosphor by conventional solid-state reaction and found that this phosphor has a very high critical concentration. Dexter and Schulman, 8 have described that the concentration quenching of the activator is related to cross relaxation and/or energy migration to quenching sites. These phenomena can be due to electromagnetic multipolar interaction or exchange interaction. To obtain insight into the mechanism responsible for the concentration quenching of the Eu 3ϩ emission in this case, we have investigated Y 2 GeO 5 :Eu phosphor over a wide concentration range. ExperimentalThe powder samples with the general formula (Y 1Ϫx Eu x ) 2 GeO 5 were prepared by the solid-state reaction method. The starting materials used in the preparation of this phosphor were powders of greater purity than 99.99% of Y 2 O 3 , GeO 2 , and Eu 2 O 3 . Preweighed powders were mixed thoroughly in acetone in an agate mortar and dried at 130°C for about 24 h to drive off the solvent and successively heat-treated at several conditions of temperature and duration time, followed by an additional grinding and firing in nitrogen atmosphere. The resulting powders were identified using an X-ray diffraction ͑XRD͒ system with Cu K␣ radiation ͑Ni filter͒. Here, only samples heat-treated at 1500°C for 3 h have been considered.The excitation and emission spectra of the fired samples were measured using a Perkin-Elmer LS-50 luminescence spectrometer with a xenon flash lamp (⌬v 1/2 ϭ 10 s). The decay measurement was performed at 594 nm emission for 5 D 0 → 7 F 1 transition and 611 nm emission for 5 D 0 → 7 F 2 transition, respectively. The pumping source was 254 nm and the pulse duration was 6 ns. Results and DiscussionIn the XRD patterns of the Y 2 GeO 5 powders heat-treated with different amounts of Eu 3ϩ , most peaks correspond to the Y 2 ...

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Section: ͓8͔mentioning

confidence: 82%

Photoluminescence Properties of Eu[sup 3+]-Activated Y[sub 2]GeO[sub 5] Phosphors

Park¹,

Ahn²,

Lim³

et al. 2003

J. Electrochem. Soc.

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“…The diffusion coefficient of energy transfer among Tb 3ϩ ions is determined to be of an order of ϳ10 Ϫ13 , which is much lower than the values for some other phosphors, e.g., 1.25 ϫ 10 Ϫ9 cm 2 /s for Tb 3 Al 5 O 12 10 and 2 ϫ 10 Ϫ9 cm 2 /s for ErF 3 . 25 Such a huge difference in diffusion coefficient between YBO 3 :Tb and these two stoichiometric phosphors (or compounds) is mainly due to the different Tb 3ϩ concentrations. The greater density of the Tb 3ϩ ion in the stoichiometric compounds enhances the diffusion coefficient.…”

Section: Resultsmentioning

confidence: 99%

Photoluminescence Behavior of Tb[sup 3+]-Activated YBO[sub 3] Phosphors

Sohn

Choi

Park

2000

J. Electrochem. Soc.

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The photoluminescence behavior of Tb-activated green phosphors has been studied for the last few decades. 1-3 But most of the efforts have been focused only on yttrium aluminum garnet (YAG):Tb phosphors, 4-11 which have been investigated for their application for projection TV. 7,8 The present investigation aims at elucidating photoluminescence properties of YBO 3 :Tb phosphor based on the possibility that this phosphor could be applied for plasma TV. The YBO 3 :Tb phosphor has a strong absorption band in the vacuum ultraviolet (VUV) range, and its luminance under VUV excitation is as high as conventional commercial green phosphors. In this regard, the YBO 3 :Tb phosphor is favorable for plasma TV. Even though the color chromaticity and decay time of (Y 1Ϫx Tb x )BO 3 phosphor still needs some improvement, this phosphor could be a potential candidate for the green component of plasma TV. Tb 3ϩ has a relatively simple energy level structure: low-energy state, 7 F j ( j ϭ 6,...,0) and excited states 5 D 4 and 5 D 3 leading to luminescence. Concentration quenching and also cross relaxation are very well known phenomena in Tb-activated phosphors, which arise in common, independent of the adopted host material. There are a lot of investigations dealing with these behaviors in YAG:Tb phosphors. 9-11 We confirmed that YBO 3 :Tb phosphor exhibits similar behavior but there is a slight difference in detail. In order to investigate in detail such behavior, YBO 3 :Tb phosphors with a wide range of Tb 3ϩ concentration from 5 ϫ 10 Ϫ4 to 5 ϫ 10 Ϫ1 were examined using several experimental skills. The excitation spectra together with diffuse reflectance spectra were first measured in the range between 100 and 350 nm, and then the emission spectra were measured both under VUV and UV excitations for various Tb 3ϩ concentrations. Time-resolved emission spectra were also obtained to examine the cross relaxation in a systematic manner. The decay curves of 5 D 4 -7 Fj and 5 D 3 -7 F j transitions are examined, respectively, and then analyzed to get to a better understanding of the decay mechanism for each transition.Experimental The materials used in the present investigation with the general formula (Y 1Ϫx Tb x )BO 3 have been prepared through the solid-state reaction for x values between 5 ϫ 10 Ϫ4 and 5 ϫ 10 Ϫ1 . The raw materials used, Y 2 O 3 , B 2 O 3 , and Tb 4 O 7 , are completely blended with a certain amount of acetone, dried, and fired at the temperature of 1200ЊC in a neutral atmosphere (in N 2 ). The firing process was then followed by a reduction process at 900ЊC by introducing the gas mixture of nitrogen and a small amount of hydrogen (2%) into the furnace so that a higher emission intensity can be obtained. Such a reduction process enhances the emission intensity by about 20%. The reduced powders were pulverized and then examined using Xray diffraction in order to check whether or not a single phase was obtained. The results confirm that the vaterite-like structure (hexagonal structure) is detected. 12-14 All the powder...

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“…1 1 ) where y is the fractional frequency fluctuation δω r /ω r . This law is also applicable to quartz resonators, where it was first introduced [3] in 1978. The phase noise is obtained from S φ (f) = (ω r /2πf) 2 S y (f), or L(f) = (1/2)S φ (f) (7.12)…”

Section: Frequency and Phase Fluctuations From 1/f Noise In Dissipationmentioning

confidence: 90%

“…in Eq, (2.30) of [3], may yield a much larger α H . Here α is the fine structure constant 1/137, m the electron's mass and m* its effective mass.…”

Section: Schottky Diode Detectorsmentioning

confidence: 99%

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Noise in THz detectors and generators

2006

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For imaging and remote sensing applications, the noise of the THz detector must be minimized. The quantum 1/f theory is introduced and used to obtain analytical expressions of noise in n + p diodes, Schottky diode THz detectors and mixers, a new type of suggested MEMS resonator based Thz detectors, QWIPs and bolometers. For the DAR and for THz communications we also consider phase noise in RTD and GaN/AlGaN HFET based THz generators.

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Extensions of Handel’s 1/f-noise equations and their semiclassical theory

Cited by 15 publications

References 8 publications

Photoluminescence Properties of Eu[sup 3+]-Activated Y[sub 2]GeO[sub 5] Phosphors

Photoluminescence Properties of Eu[sup 3+]-Activated Y[sub 2]GeO[sub 5] Phosphors

Photoluminescence Behavior of Tb[sup 3+]-Activated YBO[sub 3] Phosphors

Noise in THz detectors and generators

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