Natural-superlattice homologous single crystal thin film, method for preparation thereof, and device using said single crystal thin film

• US 20050039670A1
• Filed: 10/31/2002
• Published: 02/24/2005
• Est. Priority Date: 11/05/2001
• Status: Active Grant

• Current Assignee: Hoya Corporation, Japan Science And Technology Agency
• Original Assignee: Japan Science And Technology Agency
• Inventors: Kamiya, Toshio, Orita, Masahiro, Hirano, Masahiro, Ota, Hiromichi, Hosono, Hideo, Ueda, Kazushige
• Granted Patent: US 7,061,014 B2
• Time in Patent Office: Days
• US Class Current: 117/2
• CPC Class Codes: C30B 23/02 Epitaxial-layer growth
• CPC Class Codes: C30B 29/22 Complex oxides
• CPC Class Codes: C30B 29/68 Crystals with laminate structure, e.g. "superlattices"
• CPC Class Codes: H01L 29/45 Ohmic electrodes
• CPC Class Codes: H01L 29/4908 for thin film semiconductor, e.g. gate of TFT
• CPC Class Codes: H01L 29/66969 of devices having semiconductor bodies not comprising group 14 or group 13/15 materials comprising selenium or tellurium in uncombined form other than as impurities in semiconductor bodies of other materials, comprising cuprous oxide or cuprous iodide H01L21/02365
• CPC Class Codes: H01L 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate
• CPC Class Codes: H01L 29/78693 the semiconducting oxide being amorphous

Abstract

Disclosed is a natural-superlattice homologous single-crystal thin film, which comprises a complex oxide which is epitaxially grown on either one of a ZnO epitaxial thin film formed on a single-crystal substrate, the single-crystal substrate after disappearance of the ZnO epitaxial thin film and a ZnO single crystal. The complex oxide is expressed by the a formula: M¹M²O₃ (ZnO)_m, wherein M¹ is at least one selected from the group consisting of Ga, Fe, Sc, In, Lu, Yb, Tm, Er, Ho and Y, M² is at least one selected from the group consisting of Mn, Fe, Ga, In and Al, and m is a natural number of 1 or more. A natural-superlattice homologous single-crystal thin film formed by depositing the complex oxide and subjecting the obtained layered film to a thermal anneal treatment can be used in optimal devices, electronic devices and X-ray optical devices.

Claims

1. A natural-superlattice homologous single-crystal thin film comprising a complex oxide which is epitaxially grown on a ZnO epitaxial thin film, said complex oxide being expressed by the following formula:

M¹M²O₃ (ZnO)_m

, wherein

M¹ is at least one selected from the group consisting of Ga, Fe, Sc, In, Lu, Yb, Tm, Er, Ho and Y,

M² is at least one selected from the group consisting of Mn, Fe, Ga, In and Al, and

m is a natural number of 1 or more.

4. The homologous single-crystal thin film as defined in either one of claims 1 to 3, wherein the difference of said m in the thickness direction of said thin film is±

1 or less.

5. The homologous single-crystal thin film as defined in either one of claims 1 to 3, wherein said m is continuously changed in the thickness direction of said thin film.

6. The homologous single-crystal thin film as defined in either one of claims 1 to 3, which includes a surface region which has atomic level smoothness and an area of 0.5 μ

m×

0.5 μ

m.

10. An optical, X-ray optical or electronic device comprising the homologous single-crystal thin film as defined in either one of claims 1 to 3.

11. A transparent-thin-film field-effect transistor comprising an active layer consisting of the homologous single-crystal thin film as defined in either one of claims 1 to 3, wherein said M¹M²O₃ (ZnO)_m is InMO₃ (ZnO)_m, wherein M is at least one selected from the group consisting of In, Fe, Ga and Al, and m is an integer in the range of 1 to less than 50.

12. The transparent-thin-film field-effect transistor as defined in claim 11, wherein said homologous single-crystal thin film is formed on a heat-resistant transparent oxide single-crystal substrate.

2. A natural-superlattice homologous single-crystal thin film comprising a complex oxide which is epitaxially grown on a ZnO epitaxial thin film,

wherein said ZnO epitaxial thin film is grown on a single-crystal substrate in advance of the growth of said complex oxide, and vanished during the growth of said complex oxide to allow said epitaxially grown complex oxide to reside directly on said single-crystal substrate,

wherein said complex oxide is expressed by the following formula:

M¹M²O₃ (ZnO)_m

, wherein

M¹ is at least one selected from the group consisting of Ga, Fe, Sc, In, Lu, Yb, Tm, Er, Ho and Y,

M² is at least one selected from the group consisting of Mn, Fe, Ga, In and Al, and

m is a natural number of 1 or more.

3. A natural-superlattice homologous single-crystal thin film comprising a complex oxide which is epitaxially grown on a ZnO single crystal, said complex oxide being expressed by the following formula:

M¹M²O₃ (ZnO)_m

, wherein

M¹ is at least one selected from the group consisting of Ga, Fe, Sc, In, Lu, Yb, Tm, Er, Ho and Y,

M² is at least one selected from the group consisting of Mn, Fe, Ga, In and Al, and

m is a natural number of 1 or more.

7. A method of producing a natural-superlattice homologous single-crystal thin film, comprising:

depositing an epitaxially grown complex oxide thin film on either one of a ZnO single crystal and a ZnO epitaxial thin film, said complex oxide being expressed by the formula M¹M²O₃ (ZnO)_n (wherein;

M¹ is at least one selected from the group consisting of Ga, Fe, Sc, In, Lu, Yb, Tm, Er, Ho and Y;

M² is at least one selected from the group consisting of Mn, Fe, Ga, In and Al; and

n is a natural number of 1 or more), and

subjecting said deposited film to a thermal anneal treatment.

8. The method as defined in claim 7, wherein said thermal anneal treatment is performed while covering said deposited film with a high-melting-point compound plate to prevent the vaporization of ZnO from said deposited film.

9. The method as defined in claim 7, wherein said thermal anneal treatment is performed under the presence of ZnO vapor to prevent the vaporization of ZnO from said deposited film.