Low-Energy Ar⁺ Ion-Beam-Induced Amorphization and Chemical Modification of Potassium Titanyl Arsenate (001) Crystal Surfaces

Abstract

The effect of 1.5 keV Ar+ ion irradiation on the (001) surfaces of potassium titanyl arsenate, KTiOAsO4 (KTA), has been investigated using reflection high-energy electron diffraction (RHEED) and X-ray photoelectron spectroscopy (XPS). The (001) KTA surface is very sensitive to 1.5 keV Ar+ ion irradiation which induces significant structural modification in the top surface layers. The <As−O> bonds in the KTA crystal lattice are relatively less unstable when compared to <Ti−O>; reduction of As5+ ions with the formation of As0 and partial As loss from the top surface occurs with Ar+ ion irradiation. The formation of an unstable layer with chemically active and passive arsenic states may be a factor reducing the optical parameters and durability of nonlinear devices involving KTA.