Thermal expansion contribution to the temperature dependence of excitonic transitions in GaAs and AlGaAs

The temperature dependence of the electron spin g factor in GaAs is investigated experimentally and theoretically. Experimentally, the g factor was measured using time-resolved Faraday rotation due to Larmor precession of electron spins in the temperature range between 4.5 K and 190 K. The experiment shows an almost linear increase of the g value with the temperature. This result is in good agreement with other measurements based on photoluminescence quantum beats and timeresolved Kerr rotation up to room temperature. The experimental data are described theoretically taking into account a diminishing fundamental energy gap in GaAs due to lattice thermal dilatation and nonparabolicity of the conduction band calculated using a five-level k·p model. At higher temperatures electrons populate higher Landau levels and the average g factor is obtained from a summation over many levels. A very good description of the experimental data is obtained indicating that the observed increase of the spin g factor with the temperature is predominantly due to band's nonparabolicity.

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“…Using the values of α th (T ) one calculates ∆E dl 0 (T ). This was done by Lourenco et al [16], we replot their results in Fig. 2.…”

Section: Experiments and Theorymentioning

confidence: 99%

“…However, the phonon vibrations occur on a much slower time scale than the time the electron needs to sample the interband interactions determining the effective mass and the g factor, which are at optical frequencies. The dilatational change of the gap is given by [16] …”

Section: Experiments and Theorymentioning

confidence: 99%

Temperature dependence of the electron spingfactor in GaAs

et al. 2008

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“…Initially, they are thermally excited to higher energies, leading to a temperature-induced blueshift of the photoluminescence ͑PL͒ peak energy ͑E PL ͒ up to a maximum value, and then, the emission peak displaces to lower energies due to two independent contributions, namely, the electronphonon interaction and the lattice thermal expansion. [9][10][11] Several studies have described the blueshift of the E PL ͑T͒ due to potential fluctuations by using the term E 2 / k B T in the fitting models of the band-gap temperature dependence, where E 2 is the Gaussian dispersion of the Gaussian potential fluctuation profile. [12][13][14][15][16][17] It has been argued that under intermediated-excitation intensities, there is competition between the potential fluctuations and the band-gap renormalization effects, which is related to the radiative-recombination energy of the carriers.…”

Section: Introductionmentioning

confidence: 99%

Substrate orientation effect on potential fluctuations in multiquantum wells of GaAs∕AlGaAs

Teodoro

Dias

Laureto

et al. 2008

Journal of Applied Physics

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Suppression of nonradiative recombination process in directly Si-doped InAs/GaAs quantum dots J. Appl. Phys. 110, 103511 (2011) GaN directional couplers for integrated quantum photonics Appl. Phys. Lett. 99, 161119 (2011) Room temperature spin filtering effect in GaNAs: Role of hydrogen Appl. Phys. Lett. 99, 152109 (2011) Carrier localization and related photoluminescence in cubic AlGaN epilayers J. Appl. Phys. 110, 063517 (2011) Additional information on J. Appl. Phys. The photoluminescence ͑PL͒ technique as a function of temperature and excitation intensity was used to study the optical properties of multiquantum wells ͑MQWs͒ of GaAs/ Al x Ga 1−x As grown by molecular beam epitaxy on GaAs substrates oriented in the ͓100͔, ͓311͔A, and ͓311͔B directions. The asymmetry presented by the PL spectra of the MQWs with an apparent exponential tail in the lower-energy side and the unusual behavior of the PL peak energy versus temperature ͑blueshift͒ at low temperatures are explained by the exciton localization in the confinement potential fluctuations of the heterostructures. The PL peak energy dependence with temperature was fitted by the expression proposed by Pässler ͓Phys. Status Solidi B 200, 155 ͑1997͔͒ by subtracting the term E 2 / k B T, which considers the presence of potential fluctuations. It can be verified from the PL line shape, the full width at half maximum of PL spectra, the E values obtained from the adjustment of experimental points, and the blueshift maximum values that the samples grown in the ͓311͔A / B directions have higher potential fluctuation amplitude than the sample grown in the ͓100͔ direction. This indicates a higher degree of the superficial corrugations for the MQWs grown in the ͓311͔ direction.

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“…The fundamental band gap is therefore the only temperature dependent parameter, and the dilational contribution to the change in E 0 with T for GaAs was taken from Ref. 18. We see from Fig.…”

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confidence: 99%

Temperature dependence of the electron Landégfactor in InSb and GaAs

et al. 2008

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We report Larmor precession in bulk InSb observed in the time domain from 77 to 300 K. The optically oriented polarization precesses coherently even at 300 K. The inferred Zeeman spin splitting is strongly nonparabolic, and the electron g factor ͑g * ͒ is in good agreement with k · p theory ͑provided we take only the dilational contribution to the change in energy gap with temperature͒. We also show here that correct application of the 14-band k · p model agrees with apparently anomalous trends previously reported for GaAs and confirm that the most widely quoted formula for g * in GaAs is incomplete. DOI: 10.1103/PhysRevB.77.033204 PACS number͑s͒: 72.25.Fe, 71.70.Ej, 72.25.Rb, 78.47.-p InSb is an interesting semiconductor from the point of view of tests of semiconductor band structure calculations because the heavy constituent atoms produce large relativistic effects such as spin-orbit coupling ͑responsible for the large, negative gyromagnetic ratio͒. InSb is also a candidate material for room-temperature spintronic devices such as the Das-Datta spin transistor, which relies on a coherent spin population manipulated by the Rashba effect, and thus, detailed investigation of the spin-electronic structure in this material at room temperature is of high topical interest. In the present work, we report the experimental measurement of the g factor in InSb at temperatures up to 300 K and the theoretical evaluation of g * ͑T͒ for both InSb and GaAs.Although it has been claimed that measurements of the g factor of GaAs at 300 K are inconsistent with k · p perturbation theory, 1-4 this theory has been successfully used for decades to calculate the band structure in bulk semiconductors and heterostructures, [5][6][7][8][9][10][11][12][13][14] and, in particular, the conduction band effective mass and g factor. We show here that provided we include only the dilational change of the energy gap with temperature, 8,13 we obtain reasonable agreement between experiment and theory for the high-temperature g factor in both InSb and GaAs, and there is no anomaly. The higher band k · p parameters have only a very small effect on the electron g factor for InSb, but they are very important for GaAs; in particular, we confirm that it is essential to include the effects of the interband spin-orbit coupling parameter, which was previously ignored in the Hermann and Weisbuch formula for g * ͑Ref. 9͒ used in Refs. 1 and 2.In an externally applied magnetic field, the electron energy is given bymeasured from the ⌫ 6 conduction band edge, where B is the Bohr magneton, the quantum numbers Ϯ refer to the spin, n to the Landau level index, and k B to the component of momentum parallel to the magnetic field B. In the parabolic approximation, the effective mass and g factor, m * and g * , are constants and independent of n, k B , and B. The nonparabolicity of GaAs is usually taken to be small because the dependence of the effective mass on electron energy is small. 7 However, the g value, although small in magnitude, is significantly nonparabo...

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Thermal expansion contribution to the temperature dependence of excitonic transitions in GaAs and AlGaAs

Cited by 32 publications

References 59 publications

Temperature dependence of the electron spingfactor in GaAs

Temperature dependence of the electron spingfactor in GaAs

Substrate orientation effect on potential fluctuations in multiquantum wells of GaAs∕AlGaAs

Temperature dependence of the electron Landégfactor in InSb and GaAs

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