Theory of optical absorption in diamond, Si, Ge, and GaAs

Benedict, Lorin X.; Shirley, Eric L.; Bohn, Robert B.

doi:10.1103/physrevb.57.r9385

Cited by 190 publications

(147 citation statements)

References 15 publications

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“…The 'allowed' onephoton transition amplitude Ω (1) is in (27), the 'allowed-forbidden' two-photon transition amplitude is in (33), and the 'allowed-allowed' two-photon transition amplitude is in (35).…”

Section: Resultsmentioning

confidence: 99%

Excitonic effects on the two-color coherent control of interband transitions in bulk semiconductors

Bhat

Sipe

2005

Phys. Rev. B

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Quantum interference between one-and two-photon absorption pathways allows coherent control of interband transitions in unbiased bulk semiconductors; carrier population, carrier spin polarization, photocurrent injection, and spin current injection may all be controlled. We extend the theory of these processes to include the electron-hole interaction. Our focus is on photon energies that excite carriers above the band edge, but close enough to it so that transition amplitudes based on low order expansions in k are applicable; both allowed-allowed and allowed-forbidden two-photon transition amplitudes are included. Analytic solutions are obtained using the effective mass theory of Wannier excitons; degenerate bands are accounted for, but envelope-hole coupling is neglected. We find a Coulomb enhancement of two-color coherent control process, and relate it to the Coulomb enhancements of one-and two-photon absorption. In addition, we find a frequency dependent phase shift in the dependence of photocurrent and spin current on the optical phases.The phase shift decreases monotonically from π/2 at the band edge to 0 over an energy range governed by the exciton binding energy. It is the difference between the partial wave phase shifts of the electron-hole envelope function reached by one-and two-photon pathways.

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Section: Resultsmentioning

confidence: 99%

Excitonic effects on the two-color coherent control of interband transitions in bulk semiconductors

Bhat

Sipe

2005

Phys. Rev. B

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“…The same approach has also been used by Benedict et al (1998b) to obtain the absorption spectra of bulk Si, C, Ge, and GaAs. Moreover, they have studied the wide-gap semiconductor GaN (in its wurtzite and zincblende structures), and the insulating CaF 2 crystal (Benedict and Shirley, 1999).…”

Section: The Effects Of the Electron-hole Interactionmentioning

confidence: 99%

“…The Na 4 cluster was the first realistic system to be treated in the ab initio scheme starting from DFT and going through GW (Onida et al, 1995), with a particularly strong effect of the electron-hole interaction due to the finite size of the cluster: the first absorption peak was moved back by 1.5 eV from its GW position, with a result close to the experimental one. An increasing number of such ab initio calculations of excitonic effects in finite and extended systems (see, for example, Albrecht et al, 1997Albrecht et al, , 1998aAlbrecht et al, , 1998bBenedict et al, 1998aBenedict et al, , 1998bLouie, 1998a, 1998b) have appeared since then, generally showing a big improvement over the results of RPA and GW-RPA calculations.…”

Section: Effective Hamiltonians and Effective Interactionsmentioning

confidence: 99%

Electronic excitations: density-functional versus many-body Green’s-function approaches

2002

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Electronic excitations lie at the origin of most of the commonly measured spectra. However, the first-principles computation of excited states requires a larger effort than ground-state calculations, which can be very efficiently carried out within density-functional theory. On the other hand, two theoretical and computational tools have come to prominence for the description of electronic excitations. One of them, many-body perturbation theory, is based on a set of Green's-function equations, starting with a one-electron propagator and considering the electron-hole Green's function for the response. Key ingredients are the electron's self-energy ⌺ and the electron-hole interaction. A good approximation for ⌺ is obtained with Hedin's GW approach, using density-functional theory as a zero-order solution. First-principles GW calculations for real systems have been successfully carried out since the 1980s. Similarly, the electron-hole interaction is well described by the Bethe-Salpeter equation, via a functional derivative of ⌺. An alternative approach to calculating electronic excitations is the time-dependent density-functional theory (TDDFT), which offers the important practical advantage of a dependence on density rather than on multivariable Green's functions. This approach leads to a screening equation similar to the Bethe-Salpeter one, but with a two-point, rather than a four-point, interaction kernel. At present, the simple adiabatic local-density approximation has given promising results for finite systems, but has significant deficiencies in the description of absorption spectra in solids, leading to wrong excitation energies, the absence of bound excitonic states, and appreciable distortions of the spectral line shapes. The search for improved TDDFT potentials and kernels is hence a subject of increasing interest. It can be addressed within the framework of many-body perturbation theory: in fact, both the Green's functions and the TDDFT approaches profit from mutual insight. This review compares the theoretical and practical aspects of the two approaches and their specific numerical implementations, and presents an overview of accomplishments and work in progress. CONTENTS

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“…13͒ for the electronic self-energy ⌺ of the one-particle Green function. Very recently, progress has been made in the evaluation of the twoparticle Green function, [22][23][24] from which the optical properties can be obtained. This is done by solving the BetheSalpeter equation 25,26 ͑BSE͒, which can be mapped onto a two-body Schrödinger equation for an electron and a hole forming an exciton.…”

Section: Methodsmentioning

confidence: 99%

Ab initioprediction of the electronic and optical excitations in polythiophene: Isolated chains versus bulk polymer

et al. 2000

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initio prediction of the electronic and optical excitations in polythiophene : isolated chains versus bulk polymer. Physical Review B, 61(23), 15817-15826. DOI: 10.1103/PhysRevB.61.15817 General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. We calculate the electronic and optical excitations of polythiophene using the GW ͑G stands for one-electron Green function, W for the screened Coulomb interaction͒ approximation for the electronic self-energy, and include excitonic effects by solving the electron-hole Bethe-Salpeter equation. Two different situations are studied: excitations on isolated chains and excitations on chains in crystalline polythiophene. The dielectric tensor for the crystalline situation is obtained by modeling the polymer chains as polarizable line objects, with a long-wavelength polarizability tensor obtained from the ab initio polarizability function of the isolated chain. With this model dielectric tensor we construct a screened interaction for the crystalline case, including both intra-and interchain screening. In the crystalline situation both the quasiparticle band gap and the exciton binding energies are drastically reduced in comparison with the isolated chain. However, the optical gap is hardly affected. We expect this result to be relevant for conjugated polymers in general.

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Theory of optical absorption in diamond, Si, Ge, and GaAs

Cited by 190 publications

References 15 publications

Excitonic effects on the two-color coherent control of interband transitions in bulk semiconductors

Excitonic effects on the two-color coherent control of interband transitions in bulk semiconductors

Electronic excitations: density-functional versus many-body Green’s-function approaches

Ab initioprediction of the electronic and optical excitations in polythiophene: Isolated chains versus bulk polymer

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