Characterization of Recombination Centers in Si Epilayers After He Implantation by Direct Measurement of Local Lifetime Distribution With the AC Lifetime Profiling Technique

2004 ◽  
Vol 25 (9) ◽  
pp. 602-604 ◽  
Author(s):  
P. Spirito ◽  
S. Daliento ◽  
A. Sanseverino ◽  
L. Gialanella ◽  
M. Romano ◽  
...  
Keyword(s):  
Direct Measurement ◽  
Lifetime Distribution ◽  
Recombination Centers

scholarly journals Densified Pupil Spectrograph as High-precision Radial Velocimetry: From Direct Measurement of the Universe’s Expansion History to Characterization of Nearby Habitable Planet Candidates

2022 ◽  
Vol 163 (2) ◽  
pp. 63
Author(s):  
Taro Matsuo ◽  
Thomas P. Greene ◽  
Mahdi Qezlou ◽  
Simeon Bird ◽  
Kiyotomo Ichiki ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Direct Measurement ◽  
High Precision ◽  
Resolving Power ◽  
Line Of Sight ◽  
High Dispersion ◽  
Velocity Measurements ◽  
Habitable Planet ◽  
Airy Disk

Abstract The direct measurement of the universe’s expansion history and the search for terrestrial planets in habitable zones around solar-type stars require extremely high-precision radial-velocity measures over a decade. This study proposes an approach for enabling high-precision radial-velocity measurements from space. The concept presents a combination of a high-dispersion densified pupil spectrograph and a novel line-of-sight monitor for telescopes. The precision of the radial-velocity measurements is determined by combining the spectrophotometric accuracy and the quality of the absorption lines in the recorded spectrum. Therefore, a highly dispersive densified pupil spectrograph proposed to perform stable spectroscopy can be utilized for high-precision radial-velocity measures. A concept involving the telescope’s line-of-sight monitor is developed to minimize the change of the telescope’s line of sight over a decade. This monitor allows the precise measurement of long-term telescope drift without any significant impact on the Airy disk when the densified pupil spectra are recorded. We analytically derive the uncertainty of the radial-velocity measurements, which is caused by the residual offset of the lines of sight at two epochs. We find that the error could be reduced down to approximately 1 cm s−1, and the precision will be limited by another factor (e.g., wavelength calibration uncertainty). A combination of the high-precision spectrophotometry and the high spectral resolving power could open a new path toward the characterization of nearby non-transiting habitable planet candidates orbiting late-type stars. We present two simple and compact highly dispersed densified pupil spectrograph designs for cosmology and exoplanet sciences.

Further characterization of iodide-induced hyperthyroidism based on the direct measurement of intrathyroidal iodine stores

1992 ◽  
Vol 13 (2) ◽  
pp. 114-118
Author(s):  
M. H. JONCKHEER ◽  
B. VELKENIERS ◽  
L. VANHAELST ◽  
VAN M. BLERK
Keyword(s):  
Direct Measurement

scholarly journals Photoluminescence Characterization of Nonradiative Recombination Centers in Light Emitting Materials by Utilizing Below-Gap Excitation: A Mini Review of Two-Wavelength Excited Photoluminescence

2015 ◽  
Vol 43 ◽  
pp. 1-9
Author(s):  
Norihiko Kamata ◽  
Abu Zafor Md. Touhidul Islam
Keyword(s):  
Quantum Wells ◽  
Electrical Contact ◽  
Intensity Change ◽  
Nonradiative Recombination ◽  
Excitation Light ◽  
Light Emitting ◽  
Recombination Centers ◽  
Pl Intensity ◽  
Trap Filling

We have developed an optical method of detecting and characterizing nonradiative recombination (NRR) centers without electrical contact. The method combines a below-gap excitation (BGE) light with a conventional above-gap excitation light in photoluminescence (PL) measurement, and discriminates the PL intensity change due to switching on and off the BGE. A quantitative analysis of the detected NRR centers became possible by utilizing the saturating tendency of the PL intensity change with increasing the BGE density due to trap filling effect. Some experimental results of AlGaAs, InGaN, and AlGaN quantum wells were shown to allocate the development and present status as well as to exemplify their interpretations.

Photoluminescence Characterization of Carrier Recombination Centers in 4H-SiC Substrates by Utilizing below Gap Excitation

2017 ◽  
Vol 897 ◽  
pp. 315-318
Author(s):  
Keitaro Kondo ◽  
Norihiko Kamata ◽  
Hiroyuki Yaguchi ◽  
Shuhei Yagi ◽  
Takeshi Fukuda ◽  
...  
Keyword(s):  
Density Dependence ◽  
Intensity Change ◽  
Device Performance ◽  
Acceptor Pair ◽  
Carrier Recombination ◽  
Donor Acceptor ◽  
Recombination Centers ◽  
P Type ◽  
Growth Technology

Though the crystal growth technology of SiC is improving steadily, it is still crucial to reduce crystalline defects which act as carrier recombination (CR) centers and deteriorate device performance. We detected CR centers in a p-type 4H-SiC substrate by observing the intensity change of photoluminescence due to the addition of a below-gap excitation (BGE) light of 0.93[eV]. We noticed the temperature and the BGE density dependence of band edge (BE) emission in addition to donor acceptor pair (DAP) emission and discriminated the temperature effect from that of BGE. The BGE density dependence of the PL intensity quenching is different among the BE emission, B0- and C0-lines of the DAP, respectively. It gives us an important clue for understanding CR mechanisms inside the bandgap of SiC.

Entropy-based measure of uncertainty in past lifetime distributions

2002 ◽  
Vol 39 (02) ◽  
pp. 434-440 ◽  
Author(s):  
Antonio Di Crescenzo ◽  
Maria Longobardi
Keyword(s):  
Shannon Entropy ◽  
Lifetime Distribution ◽  
Residual Entropy ◽  
Residual Lifetime ◽  
Lifetime Distributions ◽  
The Past ◽  
Life Distributions ◽  
Measure Of Uncertainty

As proposed by Ebrahimi, uncertainty in the residual lifetime distribution can be measured by means of the Shannon entropy. In this paper, we analyse a dual characterization of life distributions that is based on entropy applied to the past lifetime. Various aspects of this measure of uncertainty are considered, including its connection with the residual entropy, the relation between its increasing nature and the DRFR property, and the effect of monotonic transformations on it.

Phase-Resolved Fluorescence Spectral and Lifetime Characterization of Commercial Humic Substances

1997 ◽  
Vol 51 (7) ◽  
pp. 921-929 ◽  
Author(s):  
Sherry L. Hemmingsen ◽  
Linda B. McGown
Keyword(s):  
Steady State ◽  
Humic Substances ◽  
Direct Measurement ◽  
Fluorescence Lifetime ◽  
Spectral Features ◽  
Good Precision ◽  
Convenient Means ◽  
Accurate Comparison ◽  
Excitation Emission Matrices

Phase-resolved excitation-emission matrices (PREEMs) are shown to provide a unique visual representation of the intrinsic fluorescence properties of humic acids under a variety of solution conditions. The calculation of spectral peak ratios in PREEMs as well as steady-state excitation-emission matrices provides a convenient means for quantitating differences between the spectra with good precision. Absorbance correction is shown to be essential for accurate comparison among spectral features. Increased detail is available from PREEMs at various modulation frequencies that reveal the distribution of fluorescence lifetime contributions across the spectral surface. Direct measurement of fluorescence lifetime recovered three ranges of lifetime components in the humic substances, <1 ns, 2–5 ns, and 8–14 ns, that are consistent with previously reported lifetimes. PREEMs, which provide a concise “survey” of how the lifetimes change across the spectrum, may aid in pinpointing spectral regions that provide the best lifetime discrimination among samples.

Characterization of ultrafast interactions with materials through the direct measurement of the optical phase

1996 ◽  
Author(s):  
Tracy S. Clement ◽  
George Rodriguez ◽  
W. M. Wood ◽  
Antoinette J. Taylor
Keyword(s):  
Direct Measurement ◽  
Optical Phase
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