Effect of Surface Roughness on the Acid Etching of Amorphous Silica

Abstract

The effect of the root-mean-square (rms) roughness on the acid etching of roughened amorphous silica was studied as a function of time using atomic force microscopy and laser light scattering. The initial size and distribution of micrometer-sized surface flaws are shown to influence the time evolution of the etching by hydrofluoric acid. The increase in the optical transparency of the samples is linked to the large increases in the correlation lengths of the sample surfaces, an effect which counteracts the accompanying rise in the rms roughness.