Surface Structure of α-Quartz Prepared by Heating and Chemical Etching

Crystalline silica (SiO₂) surfaces are used as growth substrates for carbon nanotubes and nanowires, in sensing applications, and as insulators in nanoelectronics applications. Despite its importance, the atomic surface structure of quartz still remains poorly understood, especially on the experimental side. Surface structures depend heavily on the preparation approach. Here we present a survey of common preparation approaches for α-quartz(0001) and characterize the resulting surface structures. We prepared mirror polished α-quartz (0001) by high-temperature annealing, cleaning with common solvents, and chemical etching with NaOH and KOH. Using atomic force microscopy, we find that etching leads to surface roughening while heating at high temperatures produces smooth, flat terraces on the surface. We observed a large-scale surface termination with a reconstruction periodicity of 5 nm from high temperature annealing in air, consistent with previous literature [1,2]. The study provides a pathway towards tailored surface structures for specific applications.

[1] Bart, F. & Gautier, M. Surf. Sci. 311, L671–L676 (1994).

[2] Eder, S. D. et al. Sci. Rep. 5, 14545 (2015)