Nanostructure engineering of epitaxial piezoelectric {\alpha}-quartz thin films on silicon

TL;DR

This paper demonstrates a novel, scalable method for fabricating ordered arrays of epitaxial quartz nanostructures on silicon, enabling advanced high-frequency devices with preserved piezoelectric properties.

Contribution

It introduces a new combination of lithographic techniques for large-scale, controlled fabrication of epitaxial quartz nanostructures on silicon substrates.

Findings

Epitaxial quartz nanopillars with diameters down to 50 nm were fabricated.

The quartz structures maintained their crystallinity, texture, and piezoelectricity.

The method enables the creation of high-frequency resonators and sensors.

Abstract

The monolithic integration of sub-micron quartz structures on silicon substrates is a key issue for the future development of telecommunication to the GHz frequencies. Here we report unprecedented large-scale fabrication of ordered arrays of piezoelectric epitaxial quartz nanostructures on silicon substrates by the combination of soft-chemistry and three cost effective lithographic techniques: (i) laser transfer lithography, (ii) soft nanoimprint lithography on Sr-doped SiO2 sol-gel thin films and (iii) self-assembled SrCO3 nanoparticles reactive nanomasks. Epitaxial {\alpha}-quartz nanopillars with different diameters (down to 50 nm) and heights (up to 2000 nm) were obtained for the first time. This work proves the control over the shape, micro- and nano-patterning of quartz thin films while preserving its crystallinity, texture and piezoelectricity. This work opens up the opportunity to fabricate new high frequency resonators and high sensitivity sensors relevant in different fields of application.