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.
Bergamaschini, R., Salvalaglio, M., Scaccabarozzi, A., Isa, F., Falub, C., Isella, G., et al. (2016). Temperature-controlled coalescence during the growth of Ge crystals on deeply patterned Si substrates. JOURNAL OF CRYSTAL GROWTH, 440, 86-95 [10.1016/j.jcrysgro.2016.01.035].
Temperature-controlled coalescence during the growth of Ge crystals on deeply patterned Si substrates
BERGAMASCHINI, ROBERTO
;SALVALAGLIO, MARCOSecondo
;SCACCABAROZZI, ANDREA;MONTALENTI, FRANCESCO CIMBRO MATTIAPenultimo
;MIGLIO, LEONIDAUltimo
2016
Abstract
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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.