Tailoring the crystal growth of quartz on silicon for patterning epitaxial piezoelectric films

Abstract

Epitaxial films of piezoelectric a-quartz could enable the fabrication of sensors with unprecedented sensitivity for prospective applications in electronics, biology and medicine. However, the prerequisites are harnessing the crystallization of epitaxial a-quartz and tailoring suitable film microstructures for nanostructuration. Here, we bring new insights into the crystallization of epitaxial a-quartz films on silicon (100) from the devitrification of porous silica and the control of the film microstructures: we show that by increasing the quantity of devitrifying agent (Sr) it is possible to switch from an a-quartz microstructure consisting of a porous flat film to one dominated by larger, fully dense a-quartz crystals. We also found that the film thickness, relative humidity and the nature of the surfactant play an important role in the control of the microstructure and homogeneity of the films. Via a multi-layer deposition method, we have extended the maximum thickness of the a-quartz films from a few hundreds of nm to the mm range. Moreover, we found a convenient method to combine this multilayer approach with soft lithography to pattern silica films while preserving epitaxial crystallization. This improved control over crystallization and the possibility of preparing patterned films of epitaxial a-quartz on Si substrates pave the path to future developments in applications based on electromechanics, optics and optomechanics.

Growth and Crystallization of SiO2/GeO2 Thin Films on Si(100) Substrates

“…The 0% samples were grown as a control experiment. This concentration range is similar to that used by Zhang et al in their recent CSD report [ 16 ].…”

“…It is interesting to grow quartz as a thin film, bypassing all the downscaling and transfer steps and allowing lower resonator thicknesses. This has already been explored with chemical vapor techniques [ 9 , 10 , 11 , 12 ] and chemical solution methods [ 13 , 14 , 15 , 16 , 17 ]. Most recently, it was shown by Zhou et al that GeO films can be grown with the the -quartz structure homoepitaxially on single-crystal Al O substrates by pulsed laser deposition [ 18 ].…”

“…These are alternately referred to as devitrifying agents, melting agents, or network modifiers [ 22 , 23 ]. This has been successfully applied to various thin films [ 13 , 14 , 15 , 16 , 24 , 25 ], including amorphized layers on quartz [ 26 , 27 , 28 ] and GeO structures [ 29 ]. In this work, we introduce a Sr salt to the films to act as the melting agent.…”

Structure and dynamics of FCHo2 docking on membranes

“…1.5 (0.170 ± 0.005 mm), as previously reported (29,45). Briefly, Si masters were elaborated using LIL Lithography as detailed in (45,46). PDMS (polydimethylsiloxane) reactants (90 w% RTV141A; 10 w% RTV141B from BLUESIL) were transferred onto the master and dried at 70 °C for 1 h before unmolding.…”

Mapping Cell Membrane Organization and Dynamics Using Soft Nano-Imprint Lithography

“…Molds preparation: Si masters were elaborated using LIL Lithography as previously reported 10,11 . Briefly, this procedure allows to quickly obtain periodic patterns on silicon substrates of controlled shape (square and circular, as previously described 26 , diameter and periodicity over a large surface (∼cm 2 ) without the need of a lithographic mask 13 .…”