XPS characterisation of neodymium gallate wafers

XPS examinations of NdGaO3 single crystals were performed. A change of the chemical composition was found in wafers cut from the beginning, middle and end part of a crystal grown along the [0 1 1] direction. The existence of core level satellites at low binding energy related to defects was revealed. Unpolished, polished and substrates etched with H3PO4 show a decrease of gallium concentration in relation to a broken surface and to the nominal composition. Annealing of the substrates at different temperatures causes a decomposition due to escape of gallium not only from the surface but from inner parts as well. A comparison of the wafers from the crystals grown along different crystallographic direction reveals changes of the chemical composition and a variable level of defects. This was confirmed by etch pitch density measurements. The above measurements demonstrate the high sensitivity of gallium on processing