Magnetotransport and photoluminescence of two-dimensional hole gases in Si/Si1xGex/Si heterostructures

R. Loo, L. Vescan, A. Hartmann, R. Apetz, U. Zastrow, T. Schäpers, A. Leuther, C. Dieker, H. Lüth, P. Gartner, and T. Stoica
Phys. Rev. B 50, 18113 – Published 15 December 1994
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Abstract

The electrical and optical properties of Si/Si0.8Ge0.2/Si p-type modulation-doped heterostructures grown on (001) Si using low-pressure chemical-vapor deposition are investigated by a variety of techniques. The thickness of the Si1xGex quantum well was about 15 nm and the modulation-doping effect has been obtained by two remote boron-doped ∼10-nm-thick Si layers. We found a mobility enhancement at low temperatures in all modulation-doped heterostructures. Clear Shubnikov–de Haas oscillations and quantum Hall plateaus confirm the presence of a two-dimensional hole gas. From the Hall-effect measurements a hole mobility of 6870 cm2/V s at a sheet-hole concentration of 4.5×1011 cm2 at 50 mK was obtained, which is comparable with the best published values for x=0.2. The experimental results were compared with self-consistent calculations of the valence-band diagram and hole concentration. The values for the effective mass used for the calculations were obtained by solving the 6×6 Luttinger-Kohn Hamiltonian. The photoluminescence from the Si1xGex quantum well shows excitonic behavior according to its variation with excitation power. A general trend of increasing photoluminescence intensity with the mobility of the two-dimensional hole gas was observed. The high hole mobility and strong photoluminescence reflect the good interfacial quality of the Si/Si1xGex/Si heterointerfaces grown by low-pressure chemical-vapor deposition.

  • Received 26 July 1994

DOI:https://doi.org/10.1103/PhysRevB.50.18113

©1994 American Physical Society

Authors & Affiliations

R. Loo, L. Vescan, A. Hartmann, R. Apetz, U. Zastrow, T. Schäpers, A. Leuther, C. Dieker, and H. Lüth

  • Institut für Schicht- und Ionentechnik (ISI), Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany

P. Gartner and T. Stoica

  • Institute of Physics and Technology of Materials, Bucharest, MG7, Romania

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Vol. 50, Iss. 24 — 15 December 1994

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