Photoluminescence and transmission electron microscopy investigation of SiGe quantum wires grown on patterned Si substrates

Arno Hartmann, Christel Dieker, Uschi Bangert, Roger Loo, Lili Vescan, Hans Lüth

Research output: Contribution to journalArticlepeer-review

Abstract

Growth of SiGe by low pressure chemical vapor deposition on nonplanar Si substrates is studied for nominal Ge concentrations of 0.4 ≤ x nom. Ge ≤ 1. Self-organized growth leads to the formation of approx. 30 nm wide SiGe quantum wires at convex corners of the substrate. In photoluminescence (PL) spectra of samples with x nom. Ge =0.4 we identify transitions from quantum wells on the flat parts of the substrate and from quantum wires. The energetic positions of the quantum wire transitions are in good agreement with Ge concentrations measured by spatially resolved energy dispersive X-ray spectroscopy, using a scanning transmission electron microscope (TEM). We find that the Ge concentration inside the wire is considerably lower than the nominal value for growth on planar parts of the substrate. Even for wires grown with x nom. Ge = 1, where only GeH 4 and H 2 are present during growth, PL and TEM indicate a Ge concentration as low as 32% for the wires. In such growth experiments we observe different regimes of strain relaxation. While quantum wires and wells are heavily decorated with Stranski-Krastanov islands in larger structures, smaller structures (≤ 5 μm) exhibit homogeneous thickness.

Original languageEnglish
Pages (from-to)502-509
Number of pages8
JournalApplied Surface Science
Volume104-105
DOIs
Publication statusPublished - Sep 1996
Externally publishedYes

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