Abstract by Tahereh Gholian Avval
Tahereh Gholian Avval
Chemistry and Biochemistry
Application of Atomic Layer Deposition (ALD) and Low Energy Ion Scattering (LEIS) in Determination of Surface Silanol Density of Chemically and Thermally Fused Silica
The glass surface chemistry is important for its intended application as a substrate for electronic devices. It controls properties of the material that are directly relevant to its performance. Surface hydroxyls (silanols, SiOH) are among the most polar and reactive sites on the glass and play a critical role in glass surface modifications and coatings. There have been several attempts to quantify these functional groups. Here we present a tag and count approach by coupling atomic layer deposition (ALD) and low energy ion scattering (LEIS) techniques to describe the density of surface silanols. In particular, we hydroxylated pieces of fused silica with hydrofluoric acid (HF) and then heat treated it at 200, 500, 700 and 900 °C. The samples then underwent one ALD cycle to produce ZnO. According to the LEIS measurements the surfaces that are treated at higher temperatures have less zinc at the top atomic layer indicating the heat treatment depleted the surface of silanols. This method can help us understand the effect of industrial cleaning procedures on the ALD of this important material.