Effects of Inelastic Electron Scattering on Supersmooth Sapphire Surface with Au and Pt Nanolayers

A comparative study of the inelastic electron scattering on supersmooth surfaces of sapphire single crystals, including those with gold and platinum nanolayers, was performed. The techniques of cathodoluminescence spectroscopy, probe microscopy, and energy-dispersive microanalysis, as well as additional annealing of samples in air up to 1200°C, were used. It was found that, under electron-beam irradiation, gold nanocrystals interact with sapphire surface to form etch pits on it. No such pits were found on the sapphire surface with platinum layers. The sapphire radiolysis is assumed to be the main cause of sapphire etching in the Au/Al 2 O 3 system and the increase in its cathodoluminescence in comparison with pure sapphire. The changes in the cathodoluminescence spectra of the samples of the Pt/Al 2 O 3 system are related to the electron beam defocusing on the rough surface and the platinum ability to inhibit sapphire radiolysis.