Spherulitic and rotational crystal growth of Quartz thin films

TL;DR

This paper investigates the mechanisms behind spherulitic and rotational crystal growth in Quartz thin films using EBSD, revealing how fibers grow radially and form rotational crystals, which can inform better control of thin film crystallization.

Contribution

It provides a detailed analysis of spherulitic Quartz crystal growth mechanisms and introduces a method to measure lattice rotation axes in thin films.

Findings

Crystalline colonies contain radially growing fibers.

Individual fibers form rotational crystals with bent lattice planes.

A proposed mechanism involving dislocation generation explains growth patterns.

Abstract

To obtain crystalline thin films of alpha-Quartz represents a challenge due to the tendency for the material towards spherulitic growth. Thus, understanding the mechanisms that give rise to spherulitic growth can help regulate the growth process. Here the spherulitic type of 2D crystal growth in thin amorphous Quartz films was analyzed by electron back-scatter diffraction (EBSD). EBSD was used to measure the size, orientation, and rotation of crystallographic grains in polycrystalline SiO2 and GeO2 thin films with high spatial resolution. Individual spherulitic Quartz crystal colonies contain primary and secondary single crystal fibers, which grow radially from the colony center towards its edge, and fill a near circular crystalline area completely. During their growth, individual fibers form so-called rotational crystals, when some lattice planes are continuously bent. The directions of the lattice rotation axes in the fibers were determined by an enhanced analysis of EBSD data. A possible mechanism, including the generation of the particular type of dislocation(s), is suggested.