Low-energy Ar+ ion-beam-induced amorphization and chemical modification of potassium titanyl arsenate (001) crystal surfaces

The effect of 1.5 keV At+ 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 As-0 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.