Band tails in disordered systems

Sritrakool, W.; Sa‐yakanit, V.; Glyde, H. R.

doi:10.1103/physrevb.33.1199

Cited by 77 publications

(21 citation statements)

References 23 publications

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“…4,7 In Eq. ͑4͒, Z is the impurity charge, e the electron charge, N the free-carrier concentration, L the screening length, and ⑀ s the static dielectric constant.…”

Section: Theorymentioning

confidence: 99%

Modeling of the disorder contribution to the band-tail parameter in semiconductor materials

et al. 1999

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In this paper, we present a quantitative and analytical formulation of the disorder contributions to the band-tail parameter model in semiconductor materials with Urbach exponential behavior, which arise from the influence of the bulk and grain boundary trap concentration and strain. We based our calculation on the Halperin-Lax model combined with a recent model that considered the tail parameter E 0 as the sum of interactive and disorder contributions. The resulting formulation converged to the Dow-Redfield model, which supports its validity. Our theory, applied to experimental data, yields bulk-defect and grain-boundary trap concentrations in good agreement with reports for mono-and polycrystalline semiconductors. Our model can describe wholly the band-tail parameter of any semiconductor.

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“…4,7 In Eq. ͑4͒, Z is the impurity charge, e the electron charge, N the free-carrier concentration, L the screening length, and ⑀ s the static dielectric constant.…”

Section: Theorymentioning

confidence: 99%

Modeling of the disorder contribution to the band-tail parameter in semiconductor materials

et al. 1999

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“…The localization in semiconductor alloys resemble those in amorphous semiconductors [41,42], in which strong localization is significant and of 0.1 nm order of magnitude [43]. The strong localization leads to tails below mobility edge [44][45][46]. Therefore, the localization is most likely due to the alloy disorder.…”

Section: Discussionmentioning

confidence: 86%

Auger recombination at low temperatures in InGaAs/InAlAs quantum well probed by photoluminescence

Zhu

Song

et al. 2016

Journal of Luminescence

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“…3(a). Other interpretations are a disorder-induced Urbach tail 12,14 or nonadiabatic tunneling into a soliton pair. 20 Figure 3(b) shows the near-edge absorption of the ground state and that of the n -1,2 excited states.…”

Section: Ae E (T)/dt 2 ]/2hmentioning

confidence: 99%

“…Nonadiabatic absorption may also be inferred from precise derivations of electron density of states. 11,12 Since such derivations are, in general, not feasible for many-body systems, we focus instead on deriving the leading semiclassical behavior. Furthermore, our direct evaluation of the absorption itself manifests the essential role of interference near classical turning points.…”

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confidence: 99%

Semiclassical Formalism of Optical Absorption and Breathers in Polyacetylene

1988

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A formalism for the optical absorption in a coupled electron-ion system is developed. The formalism assumes an initial trajectory with frequency much lower than electronic energy scales, and a shortmemory condition, i.e., the excited-state trajectories diverge away from the initial trajectory within one period. The result shows nonadiabatic features such as level broadening, sidebands, and tails in nonclassical regimes. We apply the formalism to breather modes in polyacetylene and show that they can account for the intragap absorption tail and for the observed photoinduced absorption at 1.35 eV. PACS numbers: 71.38.+i, 33.10.Cs, 36.20.Kd, 78.20.Bh The semiclassical description of many-body theory has been a useful approach in the study of molecules, 1 " 4 solid state, 5,6 nuclear matter, 7 elementary particles, 8 and more. 9 A coupled electron-ion system is a natural application, since the heavier ions allow for "adiabatic dynamics," 3,5 i.e., the ions obey classical dynamics while the electrons follow the ions instantaneously. The presence of an external electromagnetic field poses, however, new difficulties for this formalism by allowance of nonadiabatic effects. In particular, we consider photoexcited states for which the adiabatic potential, as a function of the ion coordinates, is near a maximum (turning point) while the minimum is far, or even infinitely far, from that of the ground state. Such unstable excitations occur in photoinduced fission of molecules or nuclei, photoexcitation during molecular collisions or photoexcitation of a well-separated electron-hole pair in semiconductors.We note that the conventional Franck-Condon 10 approximation is not sufficient to handle these cases; in particular, it leads to spurious divergences at the turning points. Nonadiabatic absorption may also be inferred from precise derivations of electron density of states. 11,12 Since such derivations are, in general, not feasible for many-body systems, we focus instead on deriving the leading semiclassical behavior. Furthermore, our direct evaluation of the absorption itself manifests the essential role of interference near classical turning points.Consider a periodic initial state with frequency COB , where the external field frequency co is comparable to the gap in the electronic spectrum. The external field leads to excited states whose ion trajectories are assumed to deviate strongly from the initial trajectory within one period. We show that this "short memory" condition, together with adiabatic conditions (e.g., co ^>COB), lead to a simple yet powerful expression for the real part of the conductivity Recr(w). We apply the formalism to the polyacetylene model 5 and find that it describes the observed intragap absorption tail 13,14 and that nonlinear localized ion oscillators, i.e., breathers, 6 can account for the unusual photoinduced absorption data. 15 " 18 A general Hamiltonian for an electron-ion system isHere q^iquqi,.. .), p = (pupi,. . .), M and V(q) are the coordinates, momenta, mass and potential energy o...

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Band tails in disordered systems

Cited by 77 publications

References 23 publications

Modeling of the disorder contribution to the band-tail parameter in semiconductor materials

Modeling of the disorder contribution to the band-tail parameter in semiconductor materials

Auger recombination at low temperatures in InGaAs/InAlAs quantum well probed by photoluminescence

Semiclassical Formalism of Optical Absorption and Breathers in Polyacetylene

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