CaTiO.sub.3 Interfacial template structure on semiconductor-based material and the growth of electroceramic thin-films in the perovskite class

A process for growing a film onto the surface of a semiconductor-based material having a surface, the process comprising the steps of:

• a) providing an atomically-clean substrate of semiconductor-based material having a surface;
• b) positioning the substrate within an oxygen-free environment;
• c) selecting an alkaline earth oxide having a lattice parameter which closely matches the lattice parameter of the material of the semiconductor-based substrate;
• d) growing a film of the alkaline earth oxide upon the surface of the substrate wherein the alkaline earth oxide of the film being grown in this step d) is commensurate with the surface of the semiconductor-based substrate;
• e) selecting an ABO.sub.3 material having a lattice parameter which closely approximates either the lattice parameter of the substrate material or the quotient of the lattice parameter of the substrate material divided by the square root of 2.0 and wherein the ABO.sub.3 material has a crystalline form comprised of two metal oxide planes wherein the metal oxide of one of the two metal oxide planes is comprised of BO.sub.2 so that the metal element B of the BO.sub.2 plane provides a small cation in the crystalline structure of the ABO.sub.3 material and wherein the metal oxide of the other of the two metal oxide planes is comprised of AO so that the metal element B provides a large cation in the crystalline structure of the ABO.sub.3 material;
• f) growing a single plane of BO.sub.2 upon the alkaline earth oxide film wherein the BO.sub.2 of the single plane is epitaxial and commensurate with the alkaline earth oxide of the alkaline earth oxide film;
• and
• g) growing a single plane of AO upon the BO.sub.2 plane so that the metal oxide AO is commensurate with the BO.sub.2 of the previously-grown BO.sub.2 plane and wherein the orientation of the grown ABO.sub.3 material is either in a cube-on-cube relationship with the substrate surface or is rotated 45.degree. with respect to the surface of the substrate so that (001) ABO.sub.3 is parallel to (001) substrate surface and ›100! ABO.sub.3 is parallel to ›110! substrate surface.

A monolithic crystalline structure comprising:

• a semiconductor substrate having a material surface provided by a face-centered-cubic lattice structure like that of silicon or silicon-germanium;
• and
• an epitaxial film overlying the material surface of the substrate wherein the epitaxial film includes a perovskite having a lattice parameter which closely approximates the quotient of the lattice parameter of the material surface divided by the square root of 2.0 and wherein the perovskite has a crystalline form comprised of two constituent metal oxide planes wherein the metal oxide of one of the two constituent metal oxide planes is comprised of TiO.sub.2 so that the Ti metal of the TiO.sub.2 plane provides a small cation in the perovskite crystalline structure and wherein the metal oxide of the other of the two constituent metal oxide planes includes another metal which provides a large cation in the perovskite crystalline structure;
• the perovskite of the epitaxial film being arranged upon the material surface so that a first single plane consisting of the perovskite constituent TiO.sub.2 is epitaxial and commensurate with the material surface of the substrate, and a second single plane consisting of the other of the two constituent metal oxide planes of the perovskite crystalline structure is commensurate with the first single plane of TiO.sub.2 and wherein the orientation of the perovskite of the epitaxial film is rotated 45.degree. with respect to the orientation of the material surface of the substrate.

A process for growing a perovskite film onto the surface of a semiconductor-based material wherein the material surface thereof is provided by a face-centered-cubic (fcc) lattice structure like that of silicon or silicon-germanium, the process comprising the steps of:

• a) providing an atomically-clean substrate of semiconductor-based material having a material surface which is provided by an fcc lattice structure like that of silicon or silicon-germanium;
• b) positioning the substrate within an oxygen-free environment;
• c) selecting an alkaline earth oxide having a lattice parameter which closely matches the lattice parameter of the material surface of the semiconductor-based substrate;
• d) growing a film of the alkaline earth oxide upon the material surface wherein the alkaline earth oxide of the film being grown in this step d) is epitaxial and fully commensurate with the material surface of the semiconductor-based substrate;
• e) selecting a perovskite having a lattice parameter which closely approximates the quotient of the lattice parameter of the material surface divided by the square root of 2.0 and wherein the perovskite has a crystalline form comprised of two metal oxide planes wherein the metal oxide of one of the two metal oxide planes is comprised of TiO.sub.2 so that the Ti metal of the TiO.sub.2 plane provides a small cation in the perovskite crystalline structure and wherein the metal oxide of the other of the two metal oxide planes includes another metal which provides a large cation in the perovskite crystalline structure;
• f) growing a single plane of TiO.sub.2 upon the alkaline earth oxide film wherein the TiO.sub.2 of the single plane is epitaxial and commensurate with the alkaline earth oxide of the alkaline earth oxide film;
• and
• g) growing a single plane comprised of the other of the two metal oxide planes of the perovskite crystalline structure upon the TiO.sub.2 plane so that the metal oxide of the other of the two metal oxide planes is epitaxial and commensurate with the TiO.sub.2 of the previously-grown TiO.sub.2 plane and wherein the orientation of the grown perovskite is rotated 45.degree. with respect to the material surface of the substrate so that (001) perovskite is parallel to (001) material surface and ›100! perovskite is parallel to ›110! material surface.

A process for growing an epitaxial film of a perovskite onto a structure including a substrate of semiconductor-based material and a film of alkaline earth oxide which directly contacts and is commensurate with the material of the substrate, the process comprising the steps of:

• a) providing a structure including a substrate of semiconductor-based material and a film of alkaline earth oxide which directly contacts and is commensurate with the material of the substrate;
• b) positioning the structure within an oxygen-free environment;
• c) selecting a first perovskite having a lattice parameter which closely approximates that of the alkaline earth oxide wherein the first perovskite has a crystalline form comprised of two metal oxide planes wherein the metal oxide of one of the two metal oxide planes is comprised of TiO.sub.2 so that the Ti metal of the TiO.sub.2 plane provides a small cation in the perovskite crystalline structure and wherein the metal oxide of the other of the two metal oxide planes includes another metal which provides a large cation in the perovskite crystalline structure;
• d) growing a single plane of TiO.sub.2 upon the surface of the alkaline earth oxide film wherein the TiO.sub.2 of the single plane is epitaxial and commensurate with the alkaline earth oxide;
• and
• e) growing a single plane comprised of the other of the two metal oxide planes of the perovskite crystalline structure upon the TiO.sub.2 plane so that the metal oxide of the other of the two metal oxide planes is epitaxial and commensurate with the TiO.sub.2 of the previously-grown TiO.sub.2 plane and wherein the orientation of the single plane grown in this step is rotated 45.degree. with respect to the alkaline earth oxide upon which the TiO.sub.2 plane of step d) is grown so that the (001) plane of the first perovskite is parallel to the (001) plane of alkaline earth oxide and the ›100! direction of the first perovskite is parallel to the ›110! direction of the alkaline earth oxide.

In a solid state electrical component including a substrate of a semiconductor-based material providing a material surface provided by a face-centered-cubic (fcc) lattice structure and a layup of one perovskite oxide overlying the material surface wherein the one perovskite oxide has a crystalline form comprised of two metal oxide planes wherein the metal oxide of one of the two metal oxide planes of the crystalline form is comprised of TiO.sub.2 so that the Ti metal of the TiO.sub.2 plane provides a small cation in the crystalline structure of the one perovskite oxide and wherein the metal oxide of the other of the two metal oxide planes of the crystalline form includes a large cation in the crystalline structure of the one perovskite oxide, the improvement characterized in that:

• the perovskite oxide in the layup of perovskite oxide is comprised of a plurality of first planes each comprised entirely of TiO.sub.2 and a plurality of second planes each comprised entirely of metal oxide wherein the metal of the metal oxide plane includes the large cation in the crystalline structure of the perovskite structure, and the first and second planes of the perovskite oxide of the layup alternate with one another as a path is traced therethrough from the material surface;
• and
• an intermediate, epitaxial and commensurate interfacial film of another perovskite is disposed between the material surface and the layup of the perovskite oxide wherein the perovskite of the interfacial film has a lattice parameter which closely approximates the quotient of the lattice parameter of the material surface divided by the square root of 2.0.

A monolithic crystalline structure comprising:

• a semiconductor substrate having a surface;
• and
• a multilayer commensurate film overlying the surface of the substrate wherein the film consists of a first commensurate stratum of single plane layers of an alkaline earth oxide (AO) and having a sodium chloride-type lattice structure and a second commensurate stratum of single plane layers of an oxide material (A'BO.sub.3) so that the multilayer film arranged upon the substrate surface can be designated (AO).sub.n (A'BO.sub.3).sub.m wherein n and m are integer repeats of single plane commensurate oxide layers;
• and
• wherein n has been selected to prevent a hydration reaction of the AO stratum with water vapor.