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Structural, electrical and optical characterization of single-crystal ErAs layers grown on GaAs by MBE.

Strukturelle, elektrische und optische Charakterisierung von ErAs hergestellt mit MBE auf GaAs


Journal of Electronic Materials 19 (1990), Nr.6, S.555-560 : Abb.,Tab.,Lit.
ISSN: 0361-5235
ISSN: 1543-186X
Fraunhofer IAF ()
MBE; metal-semiconductor-heterostructure; Metall-Halbleiter-Heterostruktur; strained layer

A detailed study is presented of the structural, electrical, and optical properties of ErAs films grown on GaAs by molecular beam epitaxy (MBE). ErAs layers 1500 A thick were grown successfully over a relatively wide range of substrate temperatures (420-580 degrees C), although overgrowth of GaAs on ErAs was found to be difficult. In-situ reflection high-energy electron diffraction (RHEED), x-ray diffraction, and Rutherford backscattering (RBS) measurements all indicate single crystal growth. Analysis of X-ray rocking curves reveals that, over the range of substrate temperatures studied, strain due to the lattice mismatch between ErAs and GaAs is completely inelastically relieved in the 1500 A thick ErAs layers. Variable-temperature Hall measurements reveal metallic behaviour in all samples, with no pronounced dependence on substrate temperature. Spectrally narrow (0.6 meV) intra 4f-shell transitions of Er(high 3+), at 1.54 m um, have been observed in ErAs epitaxial layers both in abso rption (by Fourier transform infra-red spectroscopy, FTIR) and in emission (by cathodoluminescence). The crystal-field splittings observed in the FTIR spectra are consistent with the cubic symmetry expected for the Er lattice site in unstrained ErAs, in good agreement with the x-ray analyses.