• Salvalaglio, Marco
• Miglio, Leo
• Montalenti, Francesco
• Isella, Giovanni
• Bergamaschini, Roberto
• Isa, Fabio
• Kaenel, Hans Von
• Scaccabarozzi, Andrea
• Falub, Claudiu V.

Abstract

<p>A method for growing suspended Ge films on micron -sized Si pillars in Si(001) is discussed. In [C.V. Falub et al., Science 335 (2012) 1330] vertically aligned three-dimensional Ge crystals, separated by a few tens of nanometers, were obtained by depositing several micrometers of Ge using Low-Energy Plasma-Enhanced Chemical Vapor Deposition. Here a different regime of high growth temperature is exploited in order to induce the merging of the crystals into a connected structure eventually forming a continuous, two-dimensional film. The mechanisms leading to such a behavior are discussed with the aid of an effective model of crystal growth. Both the effects of deposition and curvature-driven surface diffusion are considered to reproduce the main features of coalescence. The key enabling role of high temperature is identified with the activation of the diffusion process on a time scale competitive with the deposition rate. We demonstrate the versatility of the deposition process, which allows to switch between the formation of individual crystals and a continuous suspended film simply by tuning the growth temperature. (C) 2016 Elsevier B.V. All rights reserved.</p>

Topics

• impedance spectroscopy
• surface
• two-dimensional
• forming
• activation
• chemical vapor deposition
• aligned