Band-gap renormalization in semiconductors with multiple inequivalent valleys

Kalt, H.; Rinker, M.

doi:10.1103/physrevb.45.1139

Cited by 79 publications

(43 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…5,6,18 For a refined estimation of the injection level, we use the onset energy of the optical gain spectrum to determine the direct band gap, 19 then apply the universal formula describing the direct band gap renormalization and shrinkage in highly excited semiconductors to determine the injected carrier density. 20 This method will be discussed in more detail later. Fig.…”

mentioning

confidence: 99%

Large inherent optical gain from the direct gap transition of Ge thin films

Wang

Kimerling

Michel

et al. 2013

Applied Physics Letters

View full text Add to dashboard Cite

The recent demonstration of Ge-on-Si diode lasers renews the interest in the unique carrier dynamics of Ge involving both direct (Γ) and indirect (L) valleys. Here, we report a large inherent direct gap optical gain ≥1300 cm−1 at room temperature from both tensile-strained n+ Ge-on-Si films and intrinsic Ge-on-insulator using femtosecond transmittance spectroscopy captured before direct-to-indirect valley scattering. This inherent direct gap gain is comparable to III-V semiconductors. For n+ Ge, this transient gain is ∼25× larger than its steady state gain, suggesting that reducing Γ→L or enhancing L→Γ intervalley scattering may significantly increase the optical gain of Ge lasers.

show abstract

mentioning

confidence: 99%

Large inherent optical gain from the direct gap transition of Ge thin films

Wang

Kimerling

Michel

et al. 2013

Applied Physics Letters

View full text Add to dashboard Cite

show abstract

“…It is important to mention that the electron distribution among different minima and the corresponding band-gap reductions must be calculated in a self-consistent manner since the quasi-Fermi level depends on the band-gap energies. 15 …”

Section: High Excitation Effects a Electron-hole Plasma In A Mulmentioning

confidence: 99%

“…The modifications caused by this damping are strongly restricted to the low-energy side, i.e., it has no effect on the results that are obtained from the fit procedure. 15 For the two crossover samples we obtain carrier temperatures of 60 and 40 K, respectively. These values seem to be reasonable, although the lattice temperature was much lower at 5 K. In fact, one would not expect thermal quasiequilibrium between carriers and lattice since cool carriers recombine and the population of the X valley is maintained by hot electrons from the ⌫ valley.…”

Section: Stimulated Emission and Gainmentioning

confidence: 99%

Optical properties of (AlxGa1−x)0.52In0.48P at the crossover from a direct-gap to an indirect-gap semiconductor

Dörr

Schwarz

Wörner

et al. 1998

Journal of Applied Physics

Self Cite

View full text Add to dashboard Cite

. Optical properties of (AlxGa1-x)(0.52)In0.48P at the crossover from a direct-gap to an indirect-gap semiconductor. Journal of Applied Physics, 83(4), 2241 -2249 . DOI: 10.1063 Optical properties of "Al x Ga 1؊x … 0.52 In 0.48 P at the crossover from a direct-gap to an indirect-gap semiconductor The optical properties and the dynamics of excitons and the electron-hole plasma have been studied in disordered (Al x Ga 1Ϫx ) 0.52 In 0.48 P near to the direct-to-indirect band gap crossover. In particular we have investigated three epitaxial layers grown by solid-source molecular beam epitaxy with varying Al content x. Two of them have compositions in the immediate vicinity of the crossover point, the other is assigned to the indirect-gap regime. Both direct and indirect recombination processes contribute to the photon emission from the material. Since the relative importance of the different recombination processes depends strongly on temperature, excitation intensity, and excitation pulse duration, the processes can be identified by changing these parameters. As a result, we can determine the relative alignment of the conduction band minima and the distribution of the electrons among them. At high excitation levels the two crossover samples show stimulated emission at a photon energy of ϳ2.29 eV, i.e., in the green spectral range. Using the variable stripe length method, we find an optical gain of up to ϳ600 cm Ϫ1 at excitation levels of ϳ350 kW/cm 2 . Stimulated emission involves direct recombination. This conclusion is reached from the experiments and from line-shape modeling, including a self-consistent treatment of populations and renormalization of the conduction band minima.

show abstract

“…The Coulomb-hole term, on the other hand, describes the charge-density fluctuations around individual carriers. The general conclusions drawn from numerous studies [2][3][4] are such that for bulk materials the band-gap renormalization exhibits a universal density dependence [5], whereas the quantum-well systems show marked dependence on the well-width.The main purpose of this communication is to extend the recent calculations of Ninno et al[6] to quantum-well systems, and explore the well-width and temperature dependence of the band-gap renormalization to make more realistic contact with experiments. We demonstrate that the simple approach of calculating the band-gap renormalization, which neglects the exchange-correlation effects but fully accounts for the Coulomb-hole contribution, yields reasonable agreement with experi-SM ARTICLE 749 Revise 1st proof 30.5.96…”

mentioning

confidence: 99%

mentioning

confidence: 99%

Simplified calculations of band-gap renormalization in quantum-wells

Güven

Tanatar

1996

Superlattices and Microstructures

View full text Add to dashboard Cite

Non-linear optical properties of photoexcited semiconductor quantum-wells are of interest because of their opto-electronic device application possibilities. Many-body interactions of the optically created electrons and holes lead to the band-gap renormalization which in turn determines the absorption spectra of such systems. We employ a simplified approach to calculate the band-gap renormalization in quantum-well systems by considering the interaction of a single electron-hole pair with the collective excitations (plasmons). This method neglects the exchange-correlation effects but fully accounts for the Coulomb-hole term in the single-particle self-energy. We demonstrate that the density, temperature, and well-width dependence of the band-gap renormalization for GaAs quantum-wells within our model is in good agreement with the experimental results.1996 Academic Press LimitedNon-linear optical properties of photoexcited semiconductor quantum-wells are of interest because of their opto-electronic device application possibilities. Band-gap renormalization arising from the many-body interactions of optically created electrons and holes is an important ingredient to understand the absorption spectra of such systems. Screening in the electron-hole system leads to a renormalization of the single-particle energies. In particular, the Coulomb interaction between the carriers results in a decrease in the average charge density felt by individual particles. These manybody interactions along with the Pauli exclusion principle reduce the energy of charge carriers in valence and conduction bands. The narrowing of the band-gap affects the luminescence properties with interesting consequences for the semiconductor lasers [1].The full many-body calculations of the band-gap renormalization make use of the perturbation theory to calculate the electron and hole self-energies at the conduction and valence band edges. The contribution to the self-energy may be split into a screened-exchange and a Coulomb-hole term. The former is calculated using the screened Coulomb potential in which various models and approximations for the dielectric function is employed. The Coulomb-hole term, on the other hand, describes the charge-density fluctuations around individual carriers. The general conclusions drawn from numerous studies [2][3][4] are such that for bulk materials the band-gap renormalization exhibits a universal density dependence [5], whereas the quantum-well systems show marked dependence on the well-width.The main purpose of this communication is to extend the recent calculations of Ninno et al.[6] to quantum-well systems, and explore the well-width and temperature dependence of the band-gap renormalization to make more realistic contact with experiments. We demonstrate that the simple approach of calculating the band-gap renormalization, which neglects the exchange-correlation effects but fully accounts for the Coulomb-hole contribution, yields reasonable agreement with experi-SM ARTICLE 749 Revise 1st proof 30.5.96

show abstract

Band-gap renormalization in semiconductors with multiple inequivalent valleys

Cited by 79 publications

References 43 publications

Large inherent optical gain from the direct gap transition of Ge thin films

Large inherent optical gain from the direct gap transition of Ge thin films

Optical properties of (AlxGa1−x)0.52In0.48P at the crossover from a direct-gap to an indirect-gap semiconductor

Simplified calculations of band-gap renormalization in quantum-wells

Contact Info

Product

Resources

About