Resonant Raman scattering by strained and relaxed Ge quantum dots

Alexander G. Milekhin, Alexander I. Nikiforov, Mikhail Ladanov, Oleg P. Pchelyakov, Dmitri A. Tenne, Steffen Schulze, Dietrich R.T. Zahn

Research output: Contribution to journalConference articlepeer-review

4 Scopus citations

Abstract

Fundamental vibrations in Ge/Si structures with strained and relaxed Ge quantum dots (QDs) grown by molecular beam epitaxy were investigated using resonant Raman spectroscopy. Transmission electron microscopy experiments show that the strained Ge QDs are typical "hut clusters" with base size of 15nm and a height of 2nm. A two mode distribution in size (100-200nm and 3-6nm) is found for relaxed QDs. The Raman efficiencies of the Ge optical phonons as a function of excitation energy reveal maxima at 2.35-2.41eV attributed to the E0 resonance in Ge QDs due to electronic confinement. The frequency positions of optical phonons localized in Ge "hut clusters" under non-resonant conditions correspond to fully strained Ge QDs while the frequency position of optical phonons in relaxed Ge QDs corresponds to the value in bulk Ge. With increasing excitation energy (2.5-2.7eV) the position of the Ge optical phonons shifts downwards due to size-confinement effect of optical phonons in strained and relaxed Ge QDs, indicating the presence of a QD size distribution in Ge dot structures.

Original languageEnglish
Pages (from-to)135-140
Number of pages6
JournalMaterials Research Society Symposium Proceedings
Volume737
StatePublished - 2003
EventQuantum Confined Semiconductor Nanostructures - Boston MA, United States
Duration: 2 Dec 20025 Dec 2002

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