Enhancement of the in-plane effective mass of electrons in modulation-doped InxGa1-xAs quantum wells due to confinement effects

G. Hendorfer, M. Seto, H. Ruckser, W. Jantsch, M. Helm, G. Brunthaler, W. Jost, H. Obloh, K. Köhler, D. J. As

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22 Citations (Scopus)

Abstract

We present investigations on the in-plane effective mass of conduction electrons in pseudomorphic, strained GaAs/InxGa1-xAs/AlyGa1-yAs quantum wells. The samples are modulation doped by silicon leading to electron sheet densities in the range of 1012 cm-2 in the InxGa1-xAs layers. In photoluminescence experiments at low temperature we observe that all electrons of the two-dimensional electron gas up to the Fermi energy contribute to the luminescence. This leads to an asymmetric broadening of the luminescence line shape and indicates a breakdown of the k-conservation rule. This offers the possibility of determining the Fermi energy from the low-temperature spectra. From contactless microwave Shubnikov-de Haas measurements we determine a quantity correlated to the sheet carrier density. By combining both methods we deduce the in-plane effective electronic mass and investigate its dependence on confinement. We observe a slight increase of the mass due to the built-in strain of the pseudomorphic layers and a strong increase due to confinement effects by up to 40% for 2-nm wells. Self-consistent calculations of the electronic-energy levels, the wave functions, and the perpendicular effective mass show that the observed dependence of the effective mass on the confinement is supported from a theoretical point of view. We compare the in-plane effective mass with the perpendicular one.

Original languageEnglish
Pages (from-to)2328-2334
Number of pages7
JournalPhysical Review B
Volume48
Issue number4
DOIs
Publication statusPublished - 1993
Externally publishedYes

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