Fundamental Absorption Edge in Cadmium Sulfide

Dutton, David

doi:10.1103/physrev.112.785

Cited by 280 publications

(54 citation statements)

References 27 publications

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“…A remarkable fact is that the value of the effective mass m * does not enter the result. Note that the variation of the chemical potential as a function of temperature can be measured by resonant optical transmission spectroscopy of the fundamental absorption edge in modulation doped semiconductor quantum wells, see, e.g., [12]. Now let us briefly discuss the role of electron-electron (e-e) interactions, which are neglected in the above formalism.…”

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confidence: 99%

Quantization of entropy in a quasi-two-dimensional electron gas

2016

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We demonstrate that the partial entropy of a two-dimensional electron gas (2DEG) exhibits quantized peaks at resonances between the chemical potential and electron levels of size quantization. In the limit of no scattering, the peaks depend only on the subband quantization number and are independent on material parameters, shape of the confining potential, electron effective mass and temperature. The quantization of partial entropy is a signature of a topological phase transition in a 2DEG. In the presence of stationary disorder, the magnitude of peaks decreases. Its deviation from the quantized values is a direct measure of the disorder induced smearing of the electronic density of states. Introduction. -Low-dimensional electronic devices are important building blocks for quantum electronics. This is one of the reasons of great interest to these systems. Another reason is that size quantization of the electronic states in low-dimensional systems leads to quantization of their thermal and transport properties. The most famous are the integer [1] and fractional [2] quantum Hall effect in two-dimensional electron gas (2DEG) and conductance quantization of quasi-one-dimensional channels [3].In this Letter, we address the major thermodynamic quantity -entropy -of a quasi-two-dimensional electron gas. An elegant way to measure directly the entropy per electron, s ≡ (∂S/∂n) T , was recently demonstrated [4]. Here T is temperature. We will show that the quantization of the energy spectrum of quasi-2DEG into subbands leads to a very specific quantization of the entropy: s exhibits sharp maxima as the chemical potential µ passes through the bottoms of size quantization subbands (E i ). The value of the entropy in the N -th maximum depends only on the number of the maximum, N :

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Quantization of entropy in a quasi-two-dimensional electron gas

2016

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“…where ␤ ͑ϭ6.4 cm/GW͒ 14 is the two-photon absorption coefficient and I 0 is the impinging laser intensity ͑ϭ200 GW cm Ϫ2 ͒, and find d p ϭ13 m. dichroism of single crystal CdS in the high absorptive region, 15 the dichroic shift of the onset of the fundamental interband transition is 60 meV. The energy positions of the TPL peaks in Figs.…”

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Two-photon-excited green emission and its dichroic shift of oriented thin-film CdS on glass formed by laser deposition

Ullrich

Schroeder

Sakai

et al. 2002

Applied Physics Letters

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The photoluminescence of oriented thin-film CdS on glass formed by laser deposition was investigated employing 200 fs, 1.54 eV laser pulses at room temperature. The ultrafast excitation caused a two-photon absorption process, which results in purely green emission at the band gap. The spectra are fitted very well by the application of the van Roosbroeck–Shockley relation, density of states, and Urbach’s rule demonstrating the intrinsic character of the radiative recombination. It is further shown that the energy position of the emission peak depends on the polarization of the impinging laser beam due to the dichroism of the highly oriented films.

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“…2 CdS (14,16). Consequently, for the same incident intensity, we expect PL from more deeply penetrating 514.5-nm excitation to have greater contributions from the Se-rich compositions than PL from 457.9-nm irradiation.…”

Section: A Synthesis and Sample Compositionmentioning

confidence: 96%