(Invited) Epitaxial Oxides on Silicon for CMOS and Beyond

Abstract

A very promising way to realize advanced future devices is using single-crystalline, closely lattice matched oxides, which will be grown epitaxially on the substrate of choice. We present results for crystalline gadolinium oxides on silicon grown by solid source molecular beam epitaxy. The dielectric properties of such oxides are sensitive to small variations in structure and symmetry. For example, thin crystalline Gd2O3 films epitaxially grown on silicon exhibit dielectric constants above 20 although the known bulk value is only around 14. The reason for that “enhancement effect” is not fully understood yet. Here, we report about different investigations on strain-induced effects on dielectric properties. We explain these effects by severe strain induced structural phase deformations. Further, dielectric properties of epitaxial oxide thin films have been found to improve significantly by incorporation of suitable dopants. To achieve optimum electrical properties from such doped oxides it is important to understand the correlation between doping and the electronic structure of the material. Finally, we will demonstrate different approaches to grow Si nanostructures embedded into crystalline rare earth oxides. By efficiently exploiting the growth kinetics one could create nanostructures exhibiting various dimensions, ranging from three dimensionally confined quantum dots to the quantum wells, where the carriers are confined in only one of the dimensions.