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Verevkin AA, Ptitsina NG, Smirnov KV, Voronov BM, Gol’tsman GN, Gershenson EM, et al. Multiple Andreev reflection in hybrid AlGaAs/GaAs structures with superconducting NbN contacts. Semicond. 1999;33(5):551–4.
Abstract: The conductivity of hybrid microstructures with superconducting contacts made of niobium nitride to a semiconductor with a two-dimensional electron gas in a AlGaAs/GaAs heterostructure has been investigated. Distinctive features of the behavior of the conductivity indicate the presence of multiple Andreev reflection at scattering centers in the normal region near the superconductor-semiconductor boundary.
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Verevkin AA, Ptitsina NG, Smirnov KV, Goltsman GN, Gershenson EM, Yngvesson KS. 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.; 1997. p. 55–8.
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Verevkin AA, Ptitsina NG, Smirnov KV, Gol'tsman GN, Voronov BM, Gershenzon EM, et al. 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.; 1997. p. 163–6.
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Verevkin AA, Ptitsina NG, Smirnov KV, Gol’tsman GN, Gershenzon EM, Ingvesson KS. Direct measurements of energy relaxation times on an AlGaAs/GaAs heterointerface in the range 4.2–50 K. JETP Lett. 1996;64(5):404–9.
Abstract: The temperature dependence of the energy relaxation time τe (T) of a two-dimensional electron gas at an AlGaAs/GaAs heterointerface is measured under quasiequilibrium conditions in the region of the transition from scattering by acoustic phonons to scattering with the participation of optical phonons. The temperature interval of constant τe, where scattering by the deformation potential predominates, is determined. In the preceding, low-temperature region, where piezoacoustic and deformation-potential-induced scattering processes coexist, τ e decreases slowly with increasing temperature. Optical phonons start to participate in the scattering processes at T∼25 K (the characteristic phonon lifetime was equal to τLOτ4.5 ps). The energy losses calculated from the τe data in a model with an effective nonequilibrium electron temperature agree with the published data obtained under strong heating conditions.
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Verevkin AA, Ptitsina NG, Chulcova GM, Gol'tsman GN, Gershenzon EM, Yngvesson KS. Direct measurements of energy relaxation time of electrons in AlGaAs/GaAs heterostructures under quasi-equilibrium conditions. Surface Science. 1996;361-362:569–73.
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 AA, Ptitsina NG, Chulcova GM, Gol'Tsman GN, Gershenzon EM, Yngvesson KS. 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. 1996;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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