Strain-based control of crystal anisotropy for perovskite oxides on semiconductor-based material

Claim 2

A structure comprising: a substrate of semiconductor-based material having a surface; and a thin film of anisotropic crystalline oxide epitaxially overlying the substrate surface wherein the anisotropic crystalline oxide includes unit cells wherein each unit cell possesses a directional-dependent quality and the thin film is exposed to in-plane strain at the substrate/thin film interface so that substantially every one of the unit cells of the thin film has a geometrical shape which is influenced by the in-plane strain so that the directional-dependent quality is arranged in a predisposed orientation relative to the substrate surface.

Claim 3

The structure as defined in claim 1 wherein the directional-dependent quality of each unit cell of the thin film is oriented in either a plane which is parallel to the substrate surface or along lines normal to the substrate surface.

Claim 4

The structure as defined in claim 2 wherein the thin film material is in a state of biaxial tension so that the geometric shape of each unit cell of the thin film is characterized by a width as measured in the plane of the thin film which is greater than its height as measured normal to the plane of the thin film and so that the directional-dependent quality of each unit cell is arranged in a plane which is parallel to the substrate surface.

Claim 5

The structure as defined in claim 2 wherein the thin film material is in a state of biaxial compression so that the geometric shape of each unit cell of the thin film is characterized by a width as measured in the plane of the thin film which is smaller than its height as measured normal to the plane of the thin film and so that the directional-dependent quality of each unit cell is arranged along a line which is generally normal to the substrate surface.

Claim 6

The structure as defined in claim 2 wherein the thin film material is a ferroelectric oxide having unit cells whose dipole moment provides the directional-dependent quality of the unit cells, and the predisposed orientation of the geometries of the unit cells arranges the dipole moments of substantially all of the unit cells in either a plane which is parallel to the substrate surface or along lines normal to the substrate surface.

Claim 7

A structure comprising: a substrate of semiconductor-based material having a surface; a thin film of anisotropic crystalline oxide epitaxially overlying the substrate surface wherein the thin film consists of unit cells of an ABO 3 material having at least one AO constituent plane and at least one BO 2 constituent plane and wherein the film is arranged upon the surface of the substrate so that a first single plane consisting of a single atomic layer of said AO constituent of the ABO 3 material overlies the surface of the substrate and a second single plane consisting of a single atomic layer of said BO 2 constituent of the ABO 3 material overlies the first single plane of AO and the AO and BO 2 constituent planes form unit cells of the ABO 3 material wherein each unit cell has a directional-dependent quality, and wherein the unit cells of the crystalline oxide thin film are exposed to an in-plane strain which influences the geometry of the unit cells so that the unit cells of the thin film have geometries which are conformed to a tetragonal shape and so that the tetragonal axis of each conformed unit cell is arranged in a predisposed orientation relative to the substrate surface and so that the predisposed orientation of the geometries of the thin film orients the directional-dependent quality of substantially every one of the thin film unit cells in either a plane which is parallel to the substrate surface or along lines normal to the substrate surface.

Claim 8

A structure comprising: a substrate of semiconductor-based material having a surface; a thin film of anisotropic crystalline oxide epitaxially overlying the substrate surface wherein the thin film consists of unit cells of an ABO 3 material having at least one AO constituent plane and at least one BO 2 constituent plane and wherein the film is arranged upon the surface of the substrate so that a first single plane consisting of a single atomic layer of said AO constituent of the ABO 3 material overlies the surface of the substrate and a second single plane consisting of a single atomic layer of said BO 2 constituent of the ABO 3 material overlies the first single plane of AO and the AO and BO 2 constituent planes form unit cells of the ABO 3 material wherein each unit cell has a directional-dependent quality, and wherein the unit cells of the crystalline oxide thin film are exposed to an in-plane strain which influences the geometry of the unit cells so that the unit cells of the thin film have geometries which are conformed to a tetragonal shape and so that the tetragonal axis of each conformed unit cell is arranged in a predisposed orientation relative to the substrate surface and so that the predisposed orientation of the geometries of the thin film orients the directional-dependent quality of substantially every one of the thin film unit cells in either a plane which is parallel to the substrate surface or along lines normal to the substrate surface.

Claim 11

The structure as defined in claim 6 wherein the unit cells of the thin film material are in a state of biaxial tension so that the geometric shape of each unit cell of the thin film is characterized by a width as measured in the plane of the thin film which is greater than its height as measured normal to the plane of the thin film and so that the directional-dependent quality of each unit cell is arranged in a plane which is parallel to the substrate surface.

Claim 12

The structure as defined in claim 6 wherein the unit cells of the thin film material is a state of biaxial compression so that the geometric shape of each unit cell of the thin film is characterized by a width as measured in the plane of the thin film which is smaller than its height as measured normal to the plane of the thin film and so that the directional-dependent quality of each unit cell is arranged along lines which are generally normal to the substrate surface.

Claim 13

The structure as defined in claim 6 wherein the thin film material is a ferroelectric oxide having unit cells whose dipole moment provides the directional-dependent quality of the unit cells, and the predisposed orientation of the geometry of the thin film arranges the dipole moments of substantially all of the unit cells in either a plane which is parallel to the substrate surface or along lines normal to the substrate surface.

Claim 14

A structure comprising: a semiconductor substrate having a surface; and a crystalline film overlying the surface of the substrate wherein the film consists of unit cells of an ABO 3 material having at least one constituent plane and at least one BO 2 constituent plane wherein said ABO 3 material is either arranged in a cube-on-cube relationship with the surface of the substrate or has a lattice parameter which closely approximates the quotient of the lattice parameter of the surface of the substrate divided by the square root of 2.0, and the AO and BO 2 of the constituent planes provide a bulk single crystal of said ABO 3 material comprised of unit cells of the ABO 3 material; and the unit cells of the film being arranged upon the surface of the substrate so that a first single plane consisting of a single atomic layer of said AO constituent of the ABO 3 material overlies and is commensurate with the surface of the substrate and a second single plane consisting of a single atomic layer of said BO 2 constituent of the ABO 3 material overlies and is commensurate with the first single plane of AO; and wherein there exists at the lattice interface between the semiconductor substrate and the ABO 3 thin film either a compressed or strained condition which conforms the geometry of each unit cell of the ABO 3 thin film material into a tetragonal form so that the tetragonal axis of each unit cell of the ABO 3 thin film material is oriented in a predetermined orientation relative to the surface of the substrate so that the tetragonal axis of substantially every one of the unit cells of the ABO 3 thin film material are oriented in either a plane which is parallel to the substrate surface or normal to the substrate surface.

Claim 15

A structure comprising: a semiconductor substrate having a surface; and a crystalline film overlying the surface of the substrate wherein the film consists of unit cells of an ABO 3 material having at least one constituent plane and at least one BO 2 constituent plane wherein said ABO 3 material is either arranged in a cube-on-cube relationship with the surface of the substrate or has a lattice parameter which closely approximates the quotient of the lattice parameter of the surface of the substrate divided by the square root of 2.0, and the AO and BO 2 of the constituent planes provide a bulk single crystal of said ABO 3 material comprised of unit cells of the ABO 3 material; and the unit cells of the film being arranged upon the surface of the substrate so that a first single plane consisting of a single atomic layer of said AO constituent of the ABO 3 material overlies and is commensurate with the surface of the substrate and a second single plane consisting of a single atomic layer of said BO 2 constituent of the ABO 3 material overlies and is commensurate with the first single plane of AO; and wherein there exists at the lattice interface between the semiconductor substrate and the ABO 3 thin film either a compressed or strained condition which conforms the geometry of each unit cell of the ABO 3 thin film material into a tetragonal form so that the tetragonal axis of each unit cell of the ABO 3 thin film material is oriented in a predetermined orientation relative to the surface of the substrate so that the tetragonal axis of substantially every one of the unit cells of the ABO 3 thin film material are oriented in either a plane which is parallel to the substrate surface or normal to the substrate surface.

Claim 16

The structure as defined in claim 11 wherein each unit cell of the ABO 3 material has a dipole moment, and the predisposed orientation of the geometric form of the unit cells of ABO 3 material is effected by the condition at the lattice interface so that substantially all of the dipole moments of the unit cells of the ABO 3 thin film material are arranged substantially parallel to the surface of the substrate.

Claim 17

The structure as defined in claim 11 wherein each unit cell of the ABO 3 material has a dipole moment, and the predisposed orientation of the geometric form of the unit cells of the ABO 3 material is effected by the condition at the lattice interface so that substantially all of the dipole moments of the unit cells of the ABO 3 thin film material are arranged substantially normal to the surface of the substrate.

Claim 18

The structure as defined in claim 11 wherein the semiconductor substrate includes silicon and the thin film includes a perovskite of the BaTiO 3 class of perovskites.

Claim 19

The structure as defined in claim 11 wherein the amount of compression or strain which exists at the substrate/ABO 3 material interface is within about ±2%.

Claim 22

The device as defined in claim 16 wherein the semiconductor-based substrate is silicon.

Claim 23

The device as defined in claim 16 wherein the semiconductor-based material is silicon and the anisotropic material is ferroelectric oxide in the perovskite series.

Claim 24

The device as defined in claim 7, wherein the device is a ferroelectric field effect transistor.

Claim 25

The device as defined in claim 7 wherein the semiconductor-based material is silicon, germanium or a silicon-germanium alloy.

Claim 26

The device as defined in claim 20 wherein the device is a field effect transistor.