LiNbO3 exposed to radio-frequency plasma

Abstract Radio-frequency (27.12 MHz) glow discharge in H 2 and O, have been used for surface modification of LiNbO 3 wafers. The properties of plasma modified surface layers were dependent on the gas pressure and radio frequency (RF) input power. At pressures below 1 Torr of H 2 and input powers of 1–10 W/cm 3 , a low-resistance layer was created with a sheet resistivity of 2.6 mΩ cm. At pressures of several Torrs, an Li density drop up to a depth of 1 μm appeared, accompanied by OH − radical formation. The sample processing in oxygen plasma was aimed at restoring light transparency of the samples, which was lost during hydrogen processing. The restoration is attainable in a short time and at much lower sample temperature than under thermal bleaching. Processing under certain plasma parameters decreased the density of point defects in the material. The methods used for characterizing the plasma-modified layers were neutron depth profiling (NDP) and Rutherford backscattering (RBS), X-ray induced photoelectron spectroscopy (XPS), X-ray diffraction, visible and infrared transmission and reflection spectroscopy. The paper summarizes the results of a four year study and suggests possible applications of the findings.