Structural transformation of h-BN overlayers on Pt(111) in oxidative atmospheres

Abstract

Interaction of hexagonal boron nitride (h-BN) with gases is of great importance for its properties and applications. In the present work, the structural changes of h-BN overlayers on Pt(111) in oxidative atmospheres including O₂ and NO₂ have been investigated by using low energy electron microscopy, Auger electron spectroscopy, X-ray photoelectron spectroscopy (XPS), and near ambient pressure XPS. We find that h-BN islands can be intercalated by oxygen in 10⁻⁶ Torr O₂ at 200 °C, while oxygen intercalation of full layer h-BN around 200 °C requires near ambient pressure O₂ (0.1 Torr) or such a strong oxidant as NO₂ (10⁻⁶ Torr). h-BN overlayers can be etched away in the gases at much high temperatures, e.g. 800 °C. Upon mild oxidation in O₂ or NO₂ at temperatures of 400–450 °C, h-BN is transformed to boron oxide (BO_x) overlayers, which can be converted back to h-BN by heating in NH₃ at 800 °C.