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An, Z., Chen, J. - C., Ueda, T., Komiyama, S., & Hirakawa, K. (2005). Infrared phototransistor using capacitively coupled two-dimensional electron gas layers. Appl. Phys. Lett., 86, 172106-3.
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Cao, Q., Yoon, S. F., Tong, C. Z., Ngo, C. Y., Liu, C. Y., Wang, R., et al. (2009). Two-state competition in 1.3 μm multilayer InAs/InGaAs quantum dot lasers. Appl. Phys. Lett., 95(19), 3.
Abstract: The competition of ground state (GS) and excited state (ES) is investigated from the as-grown and thermally annealed 1.3 μm ten-layer p-doped InAs/GaAs quantum dot (QD) lasers. The modal gain competition between GS and ES are measured and analyzed around the ES threshold characteristics. Our results show that two-state competition is more significant in devices with short cavity length operating at high temperature. By comparing the as-grown and annealed devices, we demonstrate enhanced GS and suppressed ES lasing from the QD laser annealed at 600 °C for 15 s.
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Gol’tsman, G. N., & Smirnov, K. V. (2001). Electron-phonon interaction in a two-dimensional electron gas of semiconductor heterostructures at low temperatures. Jetp Lett., 74(9), 474–479.
Abstract: Theoretical and experimental works devoted to studying electron-phonon interaction in the two-dimensional electron gas of semiconductor heterostructures at low temperatures in the case of strong heating in an electric field under quasi-equilibrium conditions and in a quantizing magnetic field perpendicular to the 2D layer are considered.
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Kawano, Y., & Ishibashi, K. (2008). An on-chip near-field terahertz probe and detector. Nature Photon, 2(10), 618–621.
Abstract: The advantageous properties of terahertz waves, such as their transmission through objects opaque to visible light, are attracting attention for imaging applications. A promising approach for achieving high spatial resolution is the use of near-field imaging. Although this method has been well established in the visible and microwave regions, it is challenging to perform in the terahertz region. In the terahertz techniques investigated to date, detectors have been located remotely from the probe, which degrades sensitivity, and the influence of far-field waves is unavoidable. Here we present a new integrated detection device for terahertz near-field imaging in which all the necessary detection components — an aperture, a probe and a terahertz detector — are integrated on one semiconductor chip, which is cryogenically cooled. This scheme allows highly sensitive, high-resolution detection of the evanescent field alone and promises new capabilities for high-resolution terahertz imaging.
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Shah, J., Pinczuk, A., Gossard, A. C., & Wiegmann, W. (1985). Energy-loss rates for hot electrons and holes in GaAs quantum wells. Phys. Rev. Lett., 54, 2045–2048.
Abstract: We report the first direct determination of carrier-energy-loss rates in a semiconductor. These measurements provide fundamental insight into carrier-phonon interactions in semiconductors. Unexpectedly large differences are found in the energy-loss rates for electrons and holes in GaAs/AlGaAs quantum wells. This large difference results from an anomalously low electron-energy-loss rate, which we attribute to the presence of nonequilibrium optical phonons rather than the effects of reduced dimensionality or dynamic screening.
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Shaha, J., Pinczukb, A., Gossardb, A. C., & Wiegmannb, W. (1985). Hot carrier energy loss rates in GaAs quantum wells: large differences between electrons and holes. Phys. B+C, 134(1-3), 174–178.
Abstract: The first direct and separate determination of the hot electron and hot hole energy loss rates to the lattice shows unexpectedly large differences between electrons and holes in GaAs quantum wells. This large difference results from an anomalously low electron energy loss rate, which we attribute to the presence of non-equilibrium optical phonon rather than the effects of reduced dimensionality or dynamic screening. A model calculation of hot phonon effects is presented.
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Shangina, E. L., Smirnov, K. V., Morozov, D. V., Kovalyuk, V. V., Gol’tsman, G. N., Verevkin, A. A., et al. (2010). Concentration dependence of the intermediate frequency bandwidth of submillimeter heterodyne AlGaAs/GaAs nanostructures. Bull. Russ. Acad. Sci. Phys., 74(1), 100–102.
Abstract: The concentration dependence of the intermediate frequency bandwidth of heterodyne AlGaAs/GaAs detectors with 2D electron gas is measured using submillimeter spectroscopy with high time resolution at T= 4.2 K. The intermediate frequency bandwidth f3dBfalls from 245 to 145 MHz with increasing concentration of 2D electrons n s = (1.6-6.6) × 10[su11] cm-2. The dependence f3dB ≈ n s – 0.04±is observed in the studied concentration range; this dependence is determined by electron scattering by the deformation potential of acoustic phonons and piezoelectric scattering.
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Shangina, E. L., Smirnov, K. V., Morozov, D. V., Kovalyuk, V. V., Gol’tsman, G. N., Verevkin, A. A., et al. (2010). Frequency bandwidth and conversion loss of a semiconductor heterodyne receiver with phonon cooling of two-dimensional electrons. Semicond., 44(11), 1427–1429.
Abstract: The temperature and concentration dependences of the frequency bandwidth of terahertz heterodyne AlGaAs/GaAs detectors based on hot electron phenomena with phonon cooling of two-dimensional electrons have been measured by submillimeter spectroscopy with a high time resolution. At a temperature of 4.2 K, the frequency bandwidth at a level of 3 dB (f 3 dB) is varied from 150 to 250 MHz with a change in the concentration n s according to the power law f 3dB ∝ n −0.5 s due to the dominant contribution of piezoelectric phonon scattering. The minimum conversion loss of the semiconductor heterodyne detector is obtained in structures with a high carrier mobility (μ > 3 × 105 cm2 V−1 s−1 at 4.2 K).
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Smirnov, K. V., Ptitsina, N. G., Vakhtomin, Y. B., Verevkin, A. A., Gol’tsman, G. N., & Gershenzon, E. M. (2000). Energy relaxation of two-dimensional electrons in the quantum Hall effect regime. JETP Lett., 71(1), 31–34.
Abstract: The mm-wave spectroscopy with high temporal resolution is used to measure the energy relaxation times τe of 2D electrons in GaAs/AlGaAs heterostructures in magnetic fields B=0–4 T under quasi-equilibrium conditions at T=4.2 K. With increasing B, a considerable increase in τe from 0.9 to 25 ns is observed. For high B and low values of the filling factor ν, the energy relaxation rate τ −1e oscillates. The depth of these oscillations and the positions of maxima depend on the filling factor ν. For ν>5, the relaxation rate τ −1e is maximum when the Fermi level lies in the region of the localized states between the Landau levels. For lower values of ν, the relaxation rate is maximum at half-integer values of τ −1e when the Fermi level is coincident with the Landau level. The characteristic features of the dependence τ −1e (B) are explained by different contributions of the intralevel and interlevel electron-phonon transitions to the process of the energy relaxation of 2D electrons.
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Uchiki, H., Kobayashi, T., & Sakaki, H. (1987). Photoluminescence and energyâ€loss rates in GaAs quantum wells under highâ€density excitation. J. Appl. Phys., 62(3), 1010–1016.
Abstract: The timeâ€resolved luminescence spectra from excited conduction subbands in three samples of multiâ€quantumâ€well GaAs/AlxGa1-xAs (x=0.3 and 1) semiconductors with several well widths and barrier heights were obtained under highâ€density excitations by a 30â€ps pulsed laser at 532 nm, which generated electron–hole pairs to the concentration of 1010–1013/cm2 per well per pulse at 77 K. The temperature and the Fermi energy of electron were determined by fitting best the constructed timeâ€resolved spectrum to the observed, and the timeâ€dependent electron energy was obtained by using these parameters. The energyâ€loss rates of hot electrons are at least twice smaller than the calculated ones induced by the electronâ€polar phonon scattering, including the screening effect due to the high carrier density.
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Verevkin, A., Gershenzon, E. M., Gol'tsman, G. N., Ptitsina, N. G., Chulkova, G. M., Smirnov, K. S., et al. (2002). Direct measurements of energy relaxation times in two-dimensional structures under quasi-equilibrium conditions. In Mater. Sci. Forum (Vol. 384-3, pp. 107–116).
Abstract: A new microwave technique was successfully applied for direct studies of energy relaxation times in two-dimensional AlGaAs/GaAs structures under quasi-equilibrium conditions in the nanosecond and picosecond time scale. We report our results of energy relaxation time measurements in the temperature range 1.6-50 K, in quantum Hall effect regime in magnetic fields up to 4 T.
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Verevkin, A. A., Ptitsina, N. G., Chulcova, G. M., Gol'Tsman, G. N., Gershenzon, E. M., & Yngvesson, K. S. (1996). Determination of the limiting mobility of a two-dimensional electron gas in AlxGa1-xAs/GaAs heterostructures and direct measurement of the energy relaxation time. Phys. Rev. B Condens. Matter., 53(12), R7592–R7595.
Abstract: We present results for a method to measure directly the energy relaxation time (τe) for electrons in a single AlxGa1−xAs/GaAs heterojunction; measurements were performed from 1.6 to 15 K under quasiequilibrium conditions. We find τeαT−1 below 4 K, and τe independent of T above 4 K. We have also measured the energy-loss rate, ⟨Q⟩, by the Shubnikov-de Haas technique, and find ⟨Q⟩α(T3e−T3) for T<~4.2 K; Te is the electron temperature. The values and temperature dependence of τe and ⟨Q⟩ for T<4 K agree with calculations based on piezoelectric and deformation potential acoustic phonon scattering. At 4.2 K, we can also estimate the momentum relaxation time, τm, from our measured τe. This leads to a preliminary estimate of the phonon-limited mobility at 4.2 K of μ=3×107 cm2/Vs (ns=4.2×1011 cm−2), which agrees well with published numerical calculations, as well as with an earlier indirect estimate based on measurements on a sample with much higher mobility.
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Verevkin, A. A., Ptitsina, N. G., Chulcova, G. M., Gol'tsman, G. N., Gershenzon, E. M., & Yngvesson, K. S. (1996). Direct measurements of energy relaxation time of electrons in AlGaAs/GaAs heterostructures under quasi-equilibrium conditions. Surface Science, 361-362, 569–573.
Abstract: For the first time, results are presented of a direct measurement of the energy relaxation time τε of 2D electrons in an AlGaAs/GaAs heterojunction at T = 1 and 5–20 K. A weak temperature dependence of τε for the T > 4K range and a linear temperature dependence of the reciprocal of τε for T < 4K have been observed. The linear dependence τε−1 ≈ T in the Bloch-Gruneisen regime is direct evidence of the predominance of the piezo-electric mechanism of electron-phonon interaction in non-elastic electron scattering processes. The values of τε in this regime are in very good agreement with the results of the Karpus theory. At higher temperatures, where the deformation-potential scattering becomes noticeable, a substantial disagreement between the experimental data and the theoretical results is observed.
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Verevkin, A. A., Ptitsina, N. G., Smirnov, K. V., Gol'tsman, G. N., Voronov, B. M., Gershenzon, E. M., et al. (1997). Hot electron bolometer detectors and mixers based on a superconducting-two-dimensional electron gas-superconductor structure. In Proc. 4-th Int. Semicond. Device Research Symp. (pp. 163–166).
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Verevkin, A. A., Ptitsina, N. G., Smirnov, K. V., Goltsman, G. N., Gershenson, E. M., & Yngvesson, K. S. (1997). Direct measurements of electron energy relaxation times at an AlGaAs/GaAs heterointerface in the optical phonon scattering range. In Proc. 4-th Int. Semicond. Device Research Symp. (pp. 55–58).
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