Femtosecond time-resolved x-ray diffraction from optical coherent phonons in CdTe(111) crystal

Nakamura, Kazutaka G.; Ishii, Satoshi; Ishitsu, Shusei; Shiokawa, M.; Takahashi, Hiroshi; Kurunthu, Dharmalingam; Irisawa, Jun; Hironaka, Yoichiro; Ishioka, Kunie; Kitajima, Masahiro

doi:10.1063/1.2968212

Cited by 18 publications

(8 citation statements)

References 22 publications

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“…CdTe is a polar semiconductor with an intermediate electron-phonon coupling strength that is quantified by the polaron coupling constant 0.4 α , defined in terms of the static and high-frequency di electric constants [13]. Although CdTe is an important material with a wide range of applications such as solar cells, infrared, x-ray and γ-ray detectors [14][15][16], experimental work on its ultrafast dynamics is scarce [13,[17][18][19], especially if one compares it with the very well studied, weakly-coupled ( 0.06 α ) polar semiconductor GaAs. In [17], Ishioka et al reported the time-resolved reflectivity on bulk CdTe in a photoexcitation fluence regime of 4.4 to 88 μ J cm −2 .…”

Section: Introductionmentioning

confidence: 99%

Hot carrier relaxation in CdTe via phonon–plasmon modes

Zhong

Ostach

Scholz

et al. 2017

J. Phys.: Condens. Matter

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Carrier and lattice dynamics of laser excited CdTe was studied by time-resolved reflectivity for excitation fluences spanning about three orders of magnitude, from 0.064 to 6.14 mJ cm. At fluences below 1 mJ cm the transient reflectivity is dominated by the dynamics of hybrid phonon-plasmon modes. At fluences above 1 mJ cm the time-dependent reflectivity curves show a complex interplay between band-gap renormalization, band filling, carrier dynamics and recombination. A framework that accounts for such complex dynamics is presented and used to model the time-dependent reflectivity data. This model suggests that the excess energy of the laser-excited hot carriers is reduced much more efficiently by emitting hybrid phonon-plasmon modes rather than bare longitudinal optical phonons.

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Section: Introductionmentioning

confidence: 99%

Hot carrier relaxation in CdTe via phonon–plasmon modes

Zhong

Ostach

Scholz

et al. 2017

J. Phys.: Condens. Matter

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“…5 In general, UXRD data yield unambiguous information on the ultrafast lattice response, which is helpful for the interpretation of optical pump-probe investigations concerning complex problems in solids. [6][7][8] In theory, the changes in the occupation of phonon modes are described as phonon damping due to scattering from defects or anharmonic interaction with thermally activated phonons. [9][10][11][12] For high strain amplitudes also interactions among coherent phonons are possible, which leads to a shape change of coherent phonon pulses.…”

mentioning

confidence: 99%

Calibrated real-time detection of nonlinearly propagating strain waves

et al. 2012

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Epitaxially grown metallic oxide transducers support the generation of ultrashort strain pulses in SrTiO 3 (STO) with high amplitudes up to 0.5%. The strain amplitudes are calibrated by real-time measurements of the lattice deformation using ultrafast x-ray diffraction. We determine the speed at which the strain fronts propagate by broadband picosecond ultrasonics and conclude that, above a strain level of approx. 0.2%, the compressive and tensile strain components travel at considerably different sound velocities, indicating nonlinear wave behavior. Simulations based on an anharmonic linear-chain model are in excellent accord with the experimental findings and show how the spectrum of coherent phonon modes changes with time.

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“…The resulting electron cavity emits femtosecond terahertz radiation [160] . Applications encompass water chemistry, protein dynamics (with vibrational periods in the range of 100 fs), timeresolved X -ray diffraction, as well as analysis of phase transitions [161,162] . …”

Section: Selected X -Ray Surface/interface Analysis Methodsmentioning

confidence: 99%

Tailoring of Interfaces for the Photoelectrochemical Conversion of Solar Energy

Lewerenz

2010

Advances in Electrochemical Sciences and Engineering

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IntroductionIn the search for terrestrially applicable carbon -neutral energy sources, photoelectrochemical systems exhibit several advantageous features: examples are the facilitated junction formation at the electrolyte interface, the scalability typically achieved by self -organized processes at the solid -liquid boundary [1, 2] , lowtemperature processing, and the in situ preparation and optimization of specifi c interface conditions [3,4] . In addition, photoelectrochemical solar cells can operate in the photovoltaic [5 -9] as well as in the photoelectrocatalytic [10 -14] mode. The latter is of particular importance because global energy consumption is clearly dominated by the use of fuels compared to electricity [15] . Due to stability issues when operating a solar cell at a reactive phase boundary, such as a semiconductor -electrolyte contact, photovoltaic electrochemical solar cells have technologically not been realized despite the existence of systems that have demonstrated extended stability under operation [4,7] . As limited thermodynamic stability is also a factor for solar fuel generating devices, a general strategy is needed for the future implementation of photoelectrochemical solar energy conversion systems.At the present stage of the fi eld, a multifaceted approach appears mandatory which focuses on fundamental research regarding charge and excitation energy transfer [16 -18] , materials development, particularly in conjunction with the developments in nanoscience [19 -23] , and control of interface behavior [24 -26] . This latter aspect will be the focus of the present chapter.Besides the investigation of fundamental properties of the solid -liquid interface, the situation with a rapidly deteriorating atmospheric situation [27] also demands the use of rational screening methods for the identifi cation and examination of novel photoactive materials, material combinations, and composites [28 -30] . It is obvious that a large -scale and international research and development effort is 2 Advances in Electrochemical Science and Engineering. Edited

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Femtosecond time-resolved x-ray diffraction from optical coherent phonons in CdTe(111) crystal

Cited by 18 publications

References 22 publications

Hot carrier relaxation in CdTe via phonon–plasmon modes

Hot carrier relaxation in CdTe via phonon–plasmon modes

Calibrated real-time detection of nonlinearly propagating strain waves

Tailoring of Interfaces for the Photoelectrochemical Conversion of Solar Energy

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