Pulsed laser deposition Y2O3 on Si:: characteristics of the interfacial layer

Thin Y2O3 films were directly grown on (100) Si substrates by the pulsed laser deposition technique. It has been found by high resolution cross-section transmission electron microscopy, x-ray reflectometry and x-ray photoelectron spectroscopy (XPS) that at the interface between Si and the grown layer, an interfacial layer always formed. Depth-profiling and angle-resolved XPS investigations showed that this layer consists of a mixture of substoichiometric SiOx (x<2) and the deposited Y2O3 layer, without forming an yttrium silicate. The thickness of this interfacial layer depended on the oxygen pressure and temperature used during the deposition. The main oxygen source for its formation is the physisorbed oxygen which is trapped inside the grown layer during the laser ablation process. When the thickness of this low-k SiOx was reduced by decreasing the oxygen pressure during laser ablation below the optimum value, a marked degradation of the electrical properties of the structure was noticed.