Spinel-structured metal oxide on a substrate and method of making same by molecular beam epitaxy
OwnerScott A. Chambersinventor
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Abstract
A method of making a spinel-structured metal oxide on a substrate by molecular beam epitaxy, comprising the step of supplying activated oxygen, a first metal atom flux, and at least one other metal atom flux to the surface of the substrate, wherein the metal atom fluxes are individually controlled at the substrate so as to grow the spinel-structured metal oxide on the substrate and the metal oxide is substantially in a thermodynamically stable state during the growth of the metal oxide. A particular embodiment of the present invention encompasses a method of making a spinel-structured binary ferrite, including Co ferrite, without the need of a post-growth anneal to obtain the desired equilibrium state.
Claims19
A method of making a spinel-structured metal oxide on a substrate by molecular beam epitaxy, said metal oxide comprising oxygen atoms, first metal atoms, and at least one other metal atoms, wherein said metal atoms substantially occupy thermodynamically stable lattice positions of said metal oxide, comprising the steps of:
- providing a substrate in a growth chamber;
- reducing the pressure in the growth chamber to a pressure suitable for epitaxial growth by molecular beam epitaxy;
- heating said substrate to a suitable growth temperature;
- supplying activated oxygen, a first metal atom flux, and at least one other metal atom flux to the surface of said substrate, wherein said metal atom fluxes are individually controlled at said substrate so as to grow said spinel-structured metal oxide having said metal atoms substantially occupying thermodynamically stable lattice positions of said metal oxide during the growth of said metal oxide;
- terminating the supply of said activated oxygen, said first metal atom flux, and said at least one other metal atom flux at the surface of said substrate once the desired thickness of said metal oxide is formed on said substrate;
- and
- cooling said metal oxide to room temperature.
A method of making a spinel-structured binary ferrite on a substrate by molecular beam epitaxy, said binary ferrite comprising oxygen atoms, iron atoms, and second metal atoms, wherein said metal atoms substantially occupy thermodynamically stable lattice positions of said binary ferrite, comprising the steps of:
- providing a substrate in a growth chamber;
- reducing the pressure in the growth chamber to a pressure suitable for epitaxial growth by molecular beam epitaxy;
- supplying activated oxygen to the surface of said substrate at an oxygen pressure between 1×10−5 torr and 1×10−3 torr;
- heating said substrate to a growth temperature between 150° C. and 350° C.;
- lowering said oxygen pressure to approximately 1×10−5 torr;
- supplying an iron atom flux and a second metal atom flux to the surface of said substrate, wherein said metal atom fluxes are individually controlled at said substrate so as to grow said spinel-structured binary ferrite having said metal atoms substantially occupying thermodynamically stable lattice positions of said binary ferrite during the growth of said binary ferrite;
- terminating the supply of said activated oxygen, said iron atom flux, and said second metal atom flux at the surface of said substrate once the desired thickness of said binary ferrite is formed;
- reducing said oxygen pressure to less than 1×10−7 torr;
- and
- cooling said binary ferrite to room temperature.
A method of making a spinel-structured metal oxide on a substrate by oxygen plasma assisted molecular beam epitaxy, comprising the step of supplying activated oxygen from an oxygen plasma source, a first metal atom flux, and at least one other metal atom flux to the surface of said substrate, wherein said metal atom fluxes are individually controlled at said substrate so as to grow said spinel-structured metal oxide on said substrate and said metal oxide is substantially in a thermodynamically stable state during the growth of said metal oxide.
A method of making an inverse spinel-structured Co ferrite on a substrate by oxygen plasma assisted molecular beam epitaxy, wherein at least 90% of the cobalt atoms occupy octahedral lattice positions of the Co ferrite during growth of the Co ferrite, comprising the step of supplying activated oxygen from an oxygen plasma source, an iron atom flux, and a cobalt atom flux to the surface of said substrate, wherein said iron and cobalt atom fluxes are individually controlled at said substrate by an atomic absorption spectroscopy detection system.
Dependencies are inferred from the claim text.