Thermal stability improvement of the lanthanum aluminate/silicon interface using a thin yttrium interlayer

Abstract

We investigate the effects of an ultrathin yttrium interlayer at the interface of lanthanum aluminate and silicon with thermal annealing. Addition of the yttrium interlayer resulted in a smaller increase in the valence band offset, a reduction in the interface trap density, and a close to four-order reduction in leakage current after 800°C thermal annealing. The valence band offsets are measured with X-ray photoelectron spectroscopy and compared with those obtained from electrical measurements. The good correlation of the two measurements indicates a change in the valence band offset caused by interface dipoles. The performance improvements are attributed to a reduction in lanthanum interdiffusion and the formation of an yttrium-rich silicate interfacial layer, which minimize leakage current flow and reduce hydrogen desorption in interface trap formation. © 2010 The Electrochemical Society.