Influence of Si(001) substrate misorientation on morphological and optical properties of Ge quantum dots

Journal Article · Thu Sep 15 04:00:00 EDT 2005 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.2040004· OSTI ID:20714104

Berbezier, I; Descoins, M; Ismail, B; Maaref, H; Ronda, A ^[1]

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1. Laboratoire Materiaux et Microelectronique de Provence (L2MP); Unite Mixte de Recherche (UMR); Centre National de la Recherche Scientifique; CNRS 6137; Departement Micro-electronique et Telecommunications Technopole de Chateau-Gombert; 13451 Marseille Cedex 20 (France) and Centre de Recherche en Matiere Condensee et Nanosciences-Centre National de la Recherche Scientifique; CRMCN-CNRS; Campus de Luminy; case 913; 13288 Marseille (France) and Laboratoire de Physique des Semiconducteurs et Composants Electroniques; Faculte des Sciences de Monastir; 5019 Monastir (Tunisia)

We have investigated the correlation between morphological and optical properties of Ge dots deposited by molecular-beam epitaxy on a Si(001) surface and on a high-index Si(118) vicinal surface. Ge islands were confined on the top of an undulated Si{sub 0.5}Ge{sub 0.5} template layer according to the Stranski-Krastanov growth mode. Atomic force microscopy measurements reveal that the main effect of the vicinal substrate is to transform hut islands on a nominal (001) substrate into wire-shaped islands on (118) substrates. We have observed a direct correlation between the elongated shape and polarization anisotropy of optical transitions in island. The island photoluminescence (PL) emission is partially ({approx}25%) polarized for dots deposited on a (118) substrate. PL spectroscopy investigations as a function of temperature and excitation power are reported. The results show that the PL of islands strongly depends on the pump excitation power: it broadens and is blueshifted by 28 and 14 meV/decade for structures grown on (001) and (118), respectively, as the excitation power density increases. The significant blueshift is interpreted in terms of band bending in type II recombination. Moreover, a detailed analysis of (118) island PL band shows the presence of two main peaks that could be attributed to the different island morphologies clearly identified by transmission electron and atomic force microscopies: wire islands and dome islands.

• OSTI ID: 20714104
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 6 Vol. 98; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANISOTROPY
ATOMIC FORCE MICROSCOPY
CRYSTAL GROWTH
GERMANIUM
GERMANIUM ALLOYS
MAGNETIC ISLANDS
MOLECULAR BEAM EPITAXY
MORPHOLOGY
OPTICAL PROPERTIES
PHOTOLUMINESCENCE
POLARIZATION
POWER DENSITY
QUANTUM DOTS
RECOMBINATION
SEMICONDUCTOR MATERIALS
SILICON
SILICON ALLOYS
SPECTRAL SHIFT
SUBSTRATES
TRANSMISSION ELECTRON MICROSCOPY