Plasma processing of in a hydrogen/oxygen radio-frequency discharge

Abstract

Monocrystalline was processed in a radio-frequency (27.12 MHz) discharge in hydrogen and subsequently in oxygen and the composition of the thus produced surface layers evaluated. The hydrogen plasma treatment caused a heavy blackening of the sample due to chemical reduction. At low pressures ( Torr) the niobate structure on the sample surface was completely destroyed; only niobium and its oxides remained on the surface. At higher pressures ( Torr) the niobate structure was preserved. Hydrogenation of the surface layer was found which persisted up to 500C. Subsequent treatment in an oxygen plasma under similar processing conditions brought about the restoration of the transparency of the sample. The following methods were used for the modified surface structure analysis: neutron depth profiling, Rutherford backscattering, x-ray photoelectron spectroscopy and VIS and IR spectrometry.

Sheet resistance of LiNbO3 wafers processed in radio-frequency plasma of hydrogen

“…It suggests that the production of charge carriers becomes saturated. It follows from our previous papers [1,2,4] that a longer exposure of LN to an intense plasma (i.e. the plasma with a higher electron temperature) entails a deep structural changes in the surface layer leading to a complete destruction of the niobate structure.…”

“…The scheme of the experimental equipment has been published elsewhere [1]. The discharge tube and the sample holder inside were made from sapphire to ensure the chemical inertness.…”

“…The aim of our several year study, see e.g. [1,2,3,4], is to describe the changes and find their eventual application.…”

Single‐crystal LiNbO3 surfaces processed in low‐temperature hydrogen plasma: XPS, REELS and AFM study

“…4 A sapphire reactor (Ø 23 mm) with external r.f. (13.56 MHz) electrodes (10 cm apart) has been used, with the samples placed inside the bulk plasma.…”

Zeta potential and nanodiamond self assembly assisted diamond growth on lithium niobate and lithium tantalate single crystal

“…Normally, the growth temperatures for diamond is of the order of 800 o C [18], which is higher than the Curie temperature of LTO [26]. It has also been found in the case of LNO that the crystal structure of the surface is completely destroyed/blackened when exposed to hydrogen plasma [27]. This can be recovered to some extent by exposing to oxygen plasma, however, if diamond is grown on the surface then the LNO substrate is completely blanketed and no diffusion of oxygen can happen to reform the surface.…”