Ambipolar diffusion and spatial and time-resolved spectroscopies in semiconductor heterostructures

Vasconcellos, Áurea R.; Brasil, M. J. S. P.; Luzzi, Roberto; Silva, A. A. P.; Leite, A. H.

doi:10.1063/1.3173176

Cited by 3 publications

(1 citation statement)

References 43 publications

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“…63 In its time-dependent form, Eq. (1) has also been used to describe the kinetics of emission from photoelectric semiconductor materials, [64][65][66][67] where the emission intensity is assumed to be proportional to the minority charge carrier concentration. A similar approach can be used to describe the transport of charge carriers in inorganic, insulating materials excited by ionizing radiation, [68][69][70] such as the scintillators investigated here.…”

Section: A Charge Carrier Transport Modelmentioning

confidence: 99%

Probing grain boundaries in ceramic scintillators using x-ray radioluminescence microscopy

Podowitz

Gaumé

Feigelson

2012

Journal of Applied Physics

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X-ray radioluminescence microscopy (XRLM), a novel fluorescence microscopy technique under focused x-ray excitation, was used to characterize micro-scale luminescence of Eu:Y 2 O 3 and Ce:YAG transparent ceramics and bicrystals. The diffusion length of a known semiconductor measured by XRLM was found to be in agreement with previously measured values, illustrating its use for characterizing charge carrier transport. Emission intensity was found to drop at the boundaries in both Eu:Y 2 O 3 and Ce:YAG ceramics and bicrystals. The depletion in emission at grain boundaries was ultimately found to be related to charge carrier depletion (through either deep trapping or non-radiative recombination). A charge carrier diffusion model was used to understand the effect of grain boundaries on charge carrier transport in these scintillators. The diffusion model was found to accurately predict the spatial distribution of emission in a Ce:YAG single-crystal as a function of x-ray excitation energy. Structural and chemical characterization of grain boundaries in an Eu:Y 2 O 3 ceramic using transmission electron microscopy and secondary ion mass spectrometry mapping showed an ordered boundary region and no detectable segregation of impurities or Eu, justifying the use of an abrupt boundary condition to determine boundary recombination velocities in these materials. The boundary recombination velocities were then used to show that, for ceramics with grain sizes > $20 lm, there would be a minimal effect from the detected charge carrier depletion at grain boundaries on their bulk x-ray radioluminescence intensity. Ultimately, this study illustrates how this new XRLM technique can be used to measure charge carrier diffusion properties and how it may be coupled with microstructural and micro-scale chemical analyses to fully investigate the effect of grain boundaries on scintillator properties.

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Section: A Charge Carrier Transport Modelmentioning

confidence: 99%

Probing grain boundaries in ceramic scintillators using x-ray radioluminescence microscopy

Podowitz

Gaumé

Feigelson

2012

Journal of Applied Physics

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Response Function Theory for Many-Body Systems Away from Equilibrium: Conditions of Ultrafast-Time and Ultrasmall-Space Experimental Resolution

et al. 2014

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A Response Function Theory and Scattering Theory applicable to the study of physical properties of systems driven arbitrarily away from equilibrium, specialized for dealing with ultrafast processes and in conditions of space resolution (including nanometric scale), are presented. The derivation is done in the framework of a Gibbs-style Nonequilibrium Statistical Ensemble Formalism. It is shown the connection of the observable properties with time and space-dependent correlation functions out of equilibrium. A generalized fluctuation-dissipation theorem, which relates these correlation functions with generalized susceptibilities is derived. It is also presented the method, useful for calculations, of nonequilibrium-thermodynamic Green functions. A couple of illustration with application of the formalism, consisting of the study of optical responses in ultrafast laser spectroscopy and Raman Scattering of electrons in III-N semiconductors (of "blue diodes") driven away from equilibrium by action of electric fields of moderate to high intensities, are described.

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Thermoelastic analysis of a silicon surface under x-ray free-electron-laser irradiation

Castro

Vasconcellos

Luzzi

2010

Review of Scientific Instruments

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We present an analysis of the time evolution of a highly excited silicon substrate after partial absorption of a femtosecond soft x-ray pulse. The detailed time-dependent thermoelastic behavior of the substrate in terms of the displacements u(r,t) is derived for time delays for which the usual local thermodynamic variables, temperature T(r,t) and density n(r,t), become well-defined, namely, a few hundred femtoseconds after x-ray pulse absorption. For practical optical components under present conditions of operation with trains of pulses, we find that in a worst case scenario, already the 50th pulse in the train could be adversely affected by dynamic distortion induced by the preceding pulses [corrected]

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Ambipolar diffusion and spatial and time-resolved spectroscopies in semiconductor heterostructures

Cited by 3 publications

References 43 publications

Probing grain boundaries in ceramic scintillators using x-ray radioluminescence microscopy

Probing grain boundaries in ceramic scintillators using x-ray radioluminescence microscopy

Response Function Theory for Many-Body Systems Away from Equilibrium: Conditions of Ultrafast-Time and Ultrasmall-Space Experimental Resolution

Thermoelastic analysis of a silicon surface under x-ray free-electron-laser irradiation

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