We first discuss the limitations of Raman scattering as applied to Ge/Si nanostructures. We further summarize our recent efforts to investigate the local structure of various Ge nanostructures, namely, Ge quantum dots grown by molecular beam epitaxy (MBE) on bare Si(100), on Si(111) with a 0.3 nm coverage, and nanocrystals embedded in by x-ray absorption fine structure spectroscopy. In particular, the MBE growth of Ge dots on bare Si(100) has been studied as a function of the growth conditions: in most cases strong alloying with Si takes place. Ge nanoislands on Si(111) with coverage, on the other hand, may retain the local structure of bulk Ge and be very stable against oxidation. The Ge nanocrystals embedded in possess the structure of relaxed bulk Ge without any Ge–Si bonding. The latter two kinds of Ge nanostructures possess visible photoluminescence.
Effect of the interface on the local structure of Ge–Si nanostructures
A. V. Kolobov, H. Oyanagi, K. Brunner, G. Abstreiter, Y. Maeda, A. A. Shklyaev, S. Yamasaki, M. Ichikawa, K. Tanaka; Effect of the interface on the local structure of Ge–Si nanostructures. J. Vac. Sci. Technol. A 1 May 2002; 20 (3): 1116–1119. https://doi.org/10.1116/1.1460894
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