Open Access SPECIAL ISSUE ARTICLE

Ordered Arrays of SiGe Islands from Low-Energy PECVD

M Bollani1*, E Bonera3, D Chrastina2, A Fedorov1, V Montuori4, A Picco3, A Tagliaferri4, G Vanacore4 and R Sordan2

Author Affiliations

1 CNISM-CNR, L-NESS, via Anzani 42, 22100, Como, Italy

2 L-NESS, Politecnico di Milano, Polo regionale di Como, via Anzani 42, 22100, Como, Italy

3 LNESS and Dipartimento Scienza dei Materiali, Università Milano Bicocca, via Cozzi 53, 20125, Milan, Italy

4 Dipartimento Fisica, Politecnico di Milano, Piazza. L. da Vinci, 20133, Milan, Italy

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Nanoscale Research Letters 2010, 5:1917-1920  doi:10.1007/s11671-010-9773-0

Published: 7 September 2010

Abstract

SiGe islands have been proposed for applications in the fields of microelectronics, optoelectronics and thermoelectrics. Although most of the works in literature are based on MBE, one of the possible advantages of low-energy plasma-enhanced chemical vapor deposition (LEPECVD) is a wider range of deposition rates, which in turn results in the possibility of growing islands with a high Ge concentration. We will show that LEPECVD can be effectively used for the controlled growth of ordered arrays of SiGe islands. In order to control the nucleation of the islands, patterned Si (001) substrates were obtained by e-beam lithography (EBL) and dry etching. We realized periodic circular pits with diameters ranging from 80 to 300 nm and depths from 65 to 75 nm. Subsequently, thin films (0.8–3.2 nm) of pure Ge were deposited by LEPECVD, resulting in regular and uniform arrays of Ge-rich islands. LEPECVD allowed the use of a wide range of growth rates (0.01–0.1 nm s−1) and substrates temperatures (600–750°C), so that the Ge content of the islands could be varied. Island morphology was characterized by AFM, while μ-Raman was used to analyze the Ge content inside the islands and the composition differences between islands on patterned and unpatterned areas of the substrate.

Keywords:
Pre-patterned Si substrate; Low-energy plasma-enhanced chemical vapor deposition growth; SiGe islands; e-Beam lithography; μ-Raman