共查询到20条相似文献,搜索用时 9 毫秒
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N. N. Ledentsov N. Tsukada K. Ploog 《Applied Physics A: Materials Science & Processing》1992,54(3):261-264
The luminescence associated with residual carbon acceptors in type-I (direct-gap) ultrathin-layer superlattices (UTLS) with well and barrier widths of 22.7<L
z<25.2 Å and 11.5<L
b<14.0 Å, respectively, is composed two lines reflecting the on-center and on-edge state of the impurities. In these narrow wells the on-center acceptor binding energy increases to 60 meV in agreement with theoretical calculations for GaAs single quantum wells using a valence band offset of 500 meV. While the binding energy of the on-center state does not vary significantly within the studied L
z and L
b range, the on-edge state shows a strong dependence on the very narrow barrier width. This increase of the acceptor binding energy makes the energy position of the impurity-related luminescence in UTLS very sensitive to the actual barrier height. Investigation of the impurity-related luminescence thus provides a versatile tool to determine the band offset ratio at the heterojunction. 相似文献
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D.A. Tenne V.A. Haisler N.T. Moshegov A.I. Toropov A.P. Shebanin D.R.T. Zahn 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,8(3):371-376
We present the forward Raman scattering study of zone-centre optical phonon anisotropy in short-period GaAs/AlAs superlattices.
Experiments were performed on specially prepared superlattice structures having anti-reflection dielectric coatings and removed
substrates. The experimental data are compared with the angular dispersion of superlattice optical phonons calculated within
the dielectric susceptibility model. We have found a good agreement between the experimental data and the calculations taking
into account interface disorder.
Received 9 September 1998 and Received in final form 22 October 1998 相似文献
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《Journal of luminescence》1987,39(2):57-74
We have studied six GaAs/AlAs superlattices with periods ranging from 18 to 60 Å and different average aluminum composition. Three of these samples are shown to be direct bandgap materials whose band structure differs strongly from that of the corresponding alloy, but is correctly described by an envelope function calculation. The three remaining samples are shown to be indirect both in real and reciprocal space. The lowest energy transitions are found to arise from an exciton involving a heavy hole state mostly confined in the GaAs layer and at the Brillouin zone center (Λ), and an electronic state of X character confined in the AlAs layers. Analysis of the time decay of the luminescence shows that this is a momentum-forbidden exciton made allowed by disorder scattering, which leads to a luminescence efficiency comparable to that of the direct bandgap samples. Partial lifting of the degeneracy of the three X orbitals by the superlattice potential is also observed. Finally, we take advantage of the strong dependence of these indirect transition energies on the band discontinuities to estimate the valence band offset to be about 550 meV in this system. 相似文献
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K. S. Zhuravlev A. M. Gilinskii T. S. Shamirzaev V. V. Preobrazhenskii B. R. Semyagin M. A. Putyato S. S. Chipkin 《Physics of the Solid State》1998,40(9):1577-1581
A study is reported of steady-and nonsteady-state photoluminescence of intentionally undoped and uniformly silicon-doped type-II
(GaAs)7(AlAs)9 superlattices grown by MBE simultaneously on (311)A-and (100)-oriented GaAs substrates. It has been established that at elevated temperatures (160>T>30 K) the superlattice spectra are dominated by the line due to the donor-acceptor recombination between donors in the AlAs
layers and acceptors located in the GaAs layers. The total carrier binding energy to the donor and acceptor in a pair has
been determined.
Fiz. Tverd. Tela (St. Petersburg) 40, 1734–1739 (September 1998) 相似文献
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V. A. Volodin M. D. Efremov V. V. Preobrazhenskii B. R. Semyagin V. V. Bolotov V. A. Sachkov E. A. Galaktionov A. V. Kretinin 《JETP Letters》2000,71(11):477-480
The phonon-plasmon interaction in tunneling GaAs n /AlAs m superlattices (m=5and 6≥n≥0.6 monolayers) was studied by Raman scattering spectroscopy. The interaction of optical phonons localized in GaAs and AlAs layers with quasi-three-dimensional plasmons strengthens as the thickness of GaAs quantum wells decreases and the electronic states in the superlattices become delocalized due to tunneling. It is assumed that the plasmons also interact with the TO-like phonon modes localized in quantum islands or in thin ruffled layers. 相似文献
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《Superlattices and Microstructures》2000,27(5-6):525-528
Cyclotron resonance (CR) measurements have been carried out to evaluate the effective mass of electron in (InGaAs)n/(GaAs)nsuperlattices (SLs) and (InGaAs)n/(AlAs)nSLs. To clarify the dependence of cyclotron mass on the monolayer numbern , we measured CR signals using pulsed high-magnetic fields up to 150 T and a far-infrared laser. We found clear cyclotron resonances in the transmission of 10.6 μ m at 75 T at room temperature in (InGaAs)n/(GaAs)nSLs and little dependence on the monolayer number n in the SLs. However, for (InGaAs)n/(AlAs)nSLs, a large dependence of cyclotron mass on the monolayer number n was observed. We consider that these dependencies are related to the difference between the barrier height in the SLs and the influence of nonparabolicity on the conduction subbands in the SLs. 相似文献
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《Superlattices and Microstructures》1998,23(5):1027-1032
We present the first identification of the direct participation of the GaAs interface (IF) mode in the phonon-assisted recombinations from type-II GaAs/AlAs short-period superlattices (SPSL). This is achieved by utilizing a novel first-order resonant Raman process associated with the type-II Xz–Γ band gap to enable a direct comparison, in the same sample, of zone boundary phonons with the photoluminescence (PL) phonon satellite energies. We present PL measurements on two complementary SPSLs to identify the reversal in the parity of the GaAs IF branch, where coupling is only allowed to the IF(+) branch. We also identify weak satellites, not previously reported, between the IF(+) and LA(X) satellites. 相似文献
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