Search

Your search keyword '"Sotomayor Torres, C.M"' showing total 295 results
Start Over Author "Sotomayor Torres, C.M"
295 results on '"Sotomayor Torres, C.M"'

104. Two-dimensional excitonic emission in InAs submonolayers

Author

Yuan, Zhiliang, Xu, Zhongying, Zheng, Baozhen, Xu, Jizong, Li, Shushen, Ge, Weikun, Wang, Y, Wang, Jiannong, Chang, Leroy L., Wang, Peidong, Sotomayor Torres, C.M., Ledentsov, Nikolai N., Yuan, Zhiliang, Xu, Zhongying, Zheng, Baozhen, Xu, Jizong, Li, Shushen, Ge, Weikun, Wang, Y, Wang, Jiannong, Chang, Leroy L., Wang, Peidong, Sotomayor Torres, C.M., and Ledentsov, Nikolai N.

Abstract

Photoluminescence (PL) and time-resolved photoluminescence (TRPL) were used to study optical emissions of ultrathin InAs layers with average layer thickness ranging from 1/12 to 1 ML grown on GaAs substrates. We have found that the inhomogeneous broadening of the PL from InAs layers can be well described by the quantum-well model with InAs islands coupling to each other and being regarded as a quasiwell. From the temperature dependence of the exciton linewidth, the exciton–LO-phonon scattering coefficient was found to be comparable to that in conventional two-dimensional quantum wells. In the TRPL measurements, the PL decay time increases linearly with temperature, which is a typical characteristic of free excitons in quantum wells. All these results indicate that the excitons localized in InAs exhibit two-dimensional properties of quantum wells, despite the topographical islandlike structure.

Published
1996

107. Large Spectral Splitting of TE and TM Components of QDs in a Microcavity

Author

Maximov, M.V., primary, Krestnikov, I.L., additional, Makarov, A.G., additional, Zhukov, A.E., additional, Maleev, N.A., additional, Ustinov, V.M., additional, Tsatsulnikov, A.F., additional, Alferov, Zh.I., additional, Chernyshov, A.Yu., additional, Ledentsov, N.N., additional, Bimberg, D., additional, and Sotomayor Torres, C.M., additional

Published
2001
Full Text
View/download PDF

109. Elastic strains in GaAs/AIAs quantum dots studied by high-resolution x-ray diffraction

Author

Holy, V., Darhuber, A.A., Bauer, G., Wang, P.D., Song, Y.P., Sotomayor Torres, C.M., Holland, M.C., Holy, V., Darhuber, A.A., Bauer, G., Wang, P.D., Song, Y.P., Sotomayor Torres, C.M., and Holland, M.C.

Abstract

We have studied a GaAs/AlAs periodic quantum dot array (fabricated by electron beam lithography and reactive ion etching) using high-resolution x-ray reciprocal space mapping around the (004) and (1¯ 1¯3) reciprocal lattice points. Both the coherently and the diffusely scattered x-ray intensities were analyzed by performing two-dimensional model calculations and comparing them with the measured reciprocal space maps of the diffracted intensity. From the distribution of the diffracted intensities we deduced the average strain status in the dots. From the numerical simulations it is evident that random elastic strain fields are present, which extend through almost the whole volume of the quantum dot. The simulations of the x-ray measurements revealed that the crystalline part of the dots is considerably smaller as scanning electron micrographs would indicate, namely, 50 nm instead of 65 nm, respectively.

Published
1995

110. X-ray reciprocal space mapping of GaAs.AIAs quantum wires and quantum dots

Author

Darhuber, A.A., Koppensteiner, E., Bauer, G., Wang, P.D., Song, Y.P., Sotomayor Torres, C.M., Holland, M.C., Darhuber, A.A., Koppensteiner, E., Bauer, G., Wang, P.D., Song, Y.P., Sotomayor Torres, C.M., and Holland, M.C.

Abstract

Periodic arrays of 150 and 175 nm-wide GaAs–AlAs quantum wires and quantum dots were investigated, fabricated by electron beam lithography, and SiCl4/O2 reactive ion etching, by means of reciprocal space mapping using triple axis x-ray diffractometry. From the x-ray data the lateral periodicity of wires and dots, and the etch depth are extracted. The reciprocal space maps reveal that after the fabrication process the lattice constant along the growth direction slightly increases for the wires and even more so for the dots.

Published
1995

125. Magneto-optical properties of InAs monolayers and InyAl1−yAs self-assembled quantum dots in Ga(Al)As matrices

Author

Wang, P.D., primary, Merz, J.L., additional, Fafard, S., additional, Leon, R., additional, Leonard, D., additional, Medeiros-Ribeiro, G., additional, Oestreich, M., additional, Petroff, P.M., additional, Ledentsov, N.N., additional, Kop'ev, P.S., additional, Ustinov, V.M., additional, Uchida, K., additional, Miura, N., additional, Akiyama, H., additional, Sakaki, H., additional, and Sotomayor Torres, C.M., additional

Published
1996
Full Text
View/download PDF

130. Residual strain in Si-Si1−xGex quantum dots

Author

Tang, Y.S, primary, Sotomayor Torres, C.M, additional, Nilsson, S, additional, Dietrich, B, additional, Kissinger, W, additional, Whall, T.E, additional, Parker, E.H.C, additional, Presting, H, additional, and Kibbel, H, additional

Published
1996
Full Text
View/download PDF

132. Optical spectroscopy of self-organized nanoscale hetero-structures involving high-index surfaces

Author

Ledentsov, N.N., primary, Maximov, M.V., additional, Kop'ev, P.S., additional, Ustinov, V.M., additional, Belousov, M.V., additional, Meltser, B.Ya., additional, Ivanov, S.V., additional, Shchukin, V.A., additional, Alferov, Zh.I., additional, Grundmann, M., additional, Bimberg, D., additional, Ruvimov, S.S., additional, Richter, W., additional, Werner, P., additional, Gösele, U., additional, Heidenreich, J., additional, Wang, P.D., additional, and Sotomayor Torres, C.M., additional

Published
1995
Full Text
View/download PDF

146. Optical Properties and Lasing in CdSe-Submonolayers in a (Zn,Mg)(S,Se) Matrix

Author

Krestnikov, I.L., Ledentsov, N.N., Hoffmann, A., Bimberg, D., Ivanov, S.V., Maximov, M.V., Sakharov, A.V., Sorokin, S.V., Kopev, P.S., Alferov, Zh.I., and Sotomayor Torres, C.M.

Abstract

We have proposed and realized a new type of optoelectronic structures we refer to as excitonic waveguides which allow an ultimate shift towards the violet spectral range (460 nm at 300 K for the ZnMgSSe/GaAs materials system). The excitonic waveguiding effect is realized at the low energy side of the strong exciton absorption peak due to localized states, caused by ultrathin narrow-gap insertions. To realize the zero-phonon lasing mechanism resonant to the spectral region of resonantly enhanced refractive index one needs to break the k-selection rule preventing direct radiate exciton recombination having large in-plane k-vector dominating at high excitation densities and observation temperatures. This can be done by localizing excitons at nanoscale CdSe-rich islands formed by ultrathin CdSe insertions.

Published
1998
Full Text
View/download PDF

147. Exciton dynamics in ultrathin InAs/GaAs quantum-wells

Author

Brübach, J., Haverkort, J.E.M., Wolter, J.H., Wang, P.D., Ledentsov, N.N., Sotomayor Torres, C.M., Pang, S.W., Applied Physics, and Photonics and Semiconductor Nanophysics

Subjects
Materials science, Photoluminescence, Condensed Matter::Other, Phonon, Exciton, Resonance, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, Molecular physics, Condensed Matter::Materials Science, symbols.namesake, Excited state, symbols, Emission spectrum, Raman scattering, Excitation
Abstract

We have studied the transient behaviour of a sharp emission line, which emerges close to the heavy-hole (hh) exciton photoluminescence line in a 1.6 monolayer thick InAs layer embedded in a GaAs matrix, when the light-hole (lh) exciton transition is excited. We find, that the decaytime of the sharp line is equal to the lh-exciton lifetime for excitation on resonance, but it strongly decreases for excitation off resonance. Since in our structure the energy separation between the hhand lh-exciton transitions amount to one GaAs LO phonon we conclude, that the sharp line originates from double resonant Raman scattering for off resonant excitation, whereas it is predominantly due to resonant luminescence for excitation on resonance. The strong decrease of the intensity of the sharp line due to a temperature rise from 4 to 18K proves the existence of a well confined lh-exciton state. In addition, we performed carrier capture measurements on this structure. We find a constant capture time of 20ps at the lh-exciton transition, whereas the capture time decreases step-like from 55ps to 22ps within the hh-exciton transition. This provides clear evidence for a two-step capture process, where the lh-level acts as an intermediate capture state.

Catalog

Books, media, physical & digital resources
See catalog results