JPH09100125A - Thin film of potassium niobate, its production and optical element using the same thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a thin film of perovskite type potassium niobate useful as an optical element orientated in (110), excellent in transparency by preparing the thin film of potassium niobate on an amorphous substrate. SOLUTION: A glass substrate containing one or more of an alkaline earth metal, rare earth metal, Bi, Pb, Nb, Co, Ni and W is used as an amorphous substrate. Or a composite amorphous substrate having formed an amorphous layer containing one or more elements of the alkaline earth metal, rare earth metal, Bi, Pb, Nb, Co, Ni and W on a crystal, an amorphous or their combination substrate is used. A thin film of perovskite type potassium niobate is prepared on the amorphous substrate by PVD method, sol-gel method, CVD method, etc. Consequently, the objective thin film is obtained. Since the amorphous substrate has its wide selection of refractive index, the thin film is usable as an optical element such as optical waveguiding element, SHG element, optical switching element, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a potassium niobate thin film, a method for producing the same, and an optical element using the thin film. More specifically, the present invention relates to a perovskite-type transparent potassium niobate thin film used in the fields of optical devices, electronic devices, and the like, and is particularly excellent in transparency prepared on an amorphous substrate (11).
The present invention relates to an oriented or non-oriented perovskite type potassium niobate thin film, a method for producing the same, and an optical element using the thin film.

[0002]

_2. Description of the Related Art Conventionally, potassium niobate thin films have been manufactured by KTaO ₃ , MgAl ₂ O ₄ , (1
00) Manufactured on a crystalline substrate such as MgO (Appl.
Phys. Lett., 61, 373, 1992.
Year, Appl. Phys. Lett., Volume 65, 10
73, 1994), and in the sol-gel method (10
0) MgO, produced on a (0001) sapphire crystal substrate (J. Am. Ceram. Soc., No. 77).
Vol. 820, 1994). When a potassium niobate thin film is formed on a crystal substrate, it can be grown only on a specific surface of the crystal, so when the substrate is used as a part of the cladding of an optical waveguide, it is not possible to change the refractive index of the substrate. Since it is impossible and the crystal substrate needs to expose a specific surface, it is not easy to fabricate a surface that is finely processed with high precision.

[0003]

DISCLOSURE OF THE INVENTION The present invention is excellent in transparency and can be (110) -oriented,
The purpose of the present invention is to provide a perovskite-type potassium niobate thin film that can be used in optical elements such as SHG elements and optical switching elements.

[0004]

As a result of intensive studies to solve the above-mentioned problems, the present inventors have produced a transparent perovskite-type on a substrate by forming a potassium niobate thin film on an amorphous substrate. We have found that it is possible to produce potassium niobate thin film, and it is easy to produce transparent and oriented perovskite-type potassium niobate thin film on an amorphous substrate of a specific composition. As a result, the present invention has been completed. That is, according to the present invention, (1) a perovskite-type transparent potassium niobate thin film formed on an amorphous substrate and (2) a thin film formed on an amorphous substrate are
The perovskite-type transparent potassium niobate thin film according to item (1) having a (110) orientation, and (3) the amorphous substrate is an alkaline earth metal, a rare earth, Bi, Pb, Nb, or C.
The transparent perovskite-type thin potassium niobate thin film according to item (1), which is a glass substrate containing at least one element selected from the group consisting of o, Ni, and W, (4) the amorphous substrate is an alkaline earth metal, a rare earth, Bi, The perovskite-type transparent potassium niobate thin film according to item (2), which is a glass substrate containing at least one element of Pb and Nb, and (5) an amorphous substrate on a crystalline, amorphous or composite substrate thereof. Alkaline earth metal, rare earth, Bi, Pb, N
The perovskite-type transparent potassium niobate thin film according to item (1), which is a composite amorphous substrate on which an amorphous layer containing at least one element of b, Co, Ni, and W is formed, and (6) the amorphous substrate is crystalline. The composite perovskite according to item (2), which is a composite amorphous substrate in which an amorphous layer containing at least one element selected from alkaline earth metals, rare earths, Bi, Pb, and Nb is formed on the amorphous, amorphous, or composite substrate thereof. -Type transparent potassium niobate thin film, (7) Perovskite-type transparent potassium niobate thin film according to item (3) or (4), wherein the glass substrate has a fine groove or projecting pattern, (8) composite amorphous The substrate has a fine projection-like pattern of patterned metal electrodes on a crystalline, amorphous or composite substrate of these, (5) A transparent perovskite-type potassium niobate thin film according to item (5) or (6), which comprises forming an amorphous layer on a substrate having a fine groove or a protrusion-shaped pattern. (5) A perovskite-type transparent potassium niobate thin film according to item (5) or (6), wherein an amorphous layer is formed on a crystal, amorphous or composite substrate thereof having
A method of producing a perovskite-type transparent potassium niobate thin film, characterized by being produced on an amorphous substrate by a VD method, (11) The PVD method is a sputtering method, and the transparent perovskite-type potassium potassium niobate according to item (10). Thin film manufacturing method, (12) The thin film formed on an amorphous substrate has a (110) orientation, (10) or
(11) The method for producing a perovskite-type transparent potassium niobate thin film as described in (11), (13) the amorphous substrate is an alkaline earth metal, a rare earth, Bi, Pb, Nb, Co, Ni,
(10) The method for producing a perovskite-type transparent potassium niobate thin film according to (10) or (11), which is a glass substrate containing at least one element of W, and (14) the amorphous substrate is an alkaline earth metal. , Rare earth, Bi, Pb, N
The method for producing a perovskite-type transparent potassium niobate thin film according to the item (12), which is a glass substrate containing at least one element of b, (15) a crystalline substrate, an amorphous substrate, or a composite substrate of these, and alkaline earth. Metals, rare earths, B
An amorphous layer containing at least one element of i, Pb, Nb, Co, Ni and W is formed by any one of PVD method, sol-gel method, CVD method, LPD method and thick film printing method. Fabrication on the formed composite amorphous substrate
(10) The method for producing a perovskite-type transparent potassium niobate thin film according to (11), (16) Alkaline earth metal, rare earth, Bi, Pb, Nb on a crystal, amorphous or composite substrate thereof. A PVD method, a sol-gel method, an amorphous layer containing at least one element of
Produced on a composite amorphous substrate formed by any one of the CVD method, LPD method and thick film printing method (12)
Item 17. A method for producing a perovskite-type transparent potassium niobate thin film, (17) A transparent perovskite-type potassium potassium niobate thin film produced on an amorphous substrate according to any one of items (1) to (9) is used. Optical elements, (18)
The optical element according to item (17), wherein the optical element is an optical waveguide element, the optical element according to item (17), wherein the optical element is an SHG element, and the optical element is an optical switching element. An optical element according to item (17) is provided.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The amorphous substrate used in the present invention is not particularly limited as long as it can form a transparent perovskite type potassium niobate thin film, and a glass substrate, or ceramic, metal, glass and these A composite amorphous substrate in which an amorphous layer is formed on a substrate such as a composite, that is, a substrate having an amorphous surface can be used. The perovskite-type transparent potassium niobate thin film produced on the amorphous substrate of the present invention is
Since the refractive index of the amorphous substrate can be freely selected, it is possible to increase the degree of freedom of mode selection in light propagation and, unlike the crystal substrate, there is an advantage that the use surface of the substrate need not be considered. Furthermore, by making the perovskite type transparent potassium niobate thin film have (110) orientation, it can be used as an optically anisotropic medium oriented in a specific direction. Where (110)
The orientation means that the (110) plane of the potassium niobate thin film is parallel to the substrate surface. The potassium niobate thin film of the present invention can be suitably used as various optical elements, in particular, optical waveguide elements, SHG (second harmonic generation) elements and optical switching elements by utilizing such characteristics. In the present invention, a method for producing a perovskite-type transparent potassium niobate thin film is PVD.
The method (physical vapor deposition method) is preferable, and it can be produced by, for example, a sputtering method or a molecular beam epitaxy method. The sputtering method is, for example, a target formed by mixing potassium niobate powder and potassium carbonate powder and adhering it to quartz glass or the like, in an argon gas-oxygen gas atmosphere, by performing high-frequency magnetron sputtering, on an amorphous substrate. A perovskite type transparent potassium niobate thin film can be produced.

In the present invention, as an amorphous substrate, an alkaline earth metal such as Ba, Sr, Ca or Mg,
La, Y, Gd, Yb and other rare earth elements, Bi, Pb, N
A glass substrate containing at least one element selected from b, Co, Ni, and W can be used. As such a glass substrate, for example, SiO ₂ —Al ₂ O ₃ —BaO—
B ₂ O ₃ type _{glass, SiO 2 -Al 2 O 3 -BaO} -CaO
System _{glass, SiO 2 -Al 2 O 3 -BaO} -SrO based _{glass, SiO 2 -Al 2 O 3 -CaO} -La 2 O 3 based glass,
_{SiO 2 -Al 2 O 3 -BaO-} B 2 O 3 -Bi 2 O 3 based _{glass, SiO 2 -Al 2 O 3 -BaO} -PbO based glass, S
_{iO 2 -Al 2 O 3 -BaO-} MgO -based glass, SiO ₂ -
_{Al 2 O 3 -B 2 O 3} -CoO based glass, SiO ₂ -Al ₂ O
_{3 -B 2 O 3 -Nb 2 O} 5 based glass, SiO ₂ -Al ₂ O ₃ -B
₂ O ₃ -NiO-based _{glass, SiO 2 -Al 2 O 3 -B} 2 O 3 -
Examples thereof include glass substrates such as WO ₃ type glass. By using such a glass substrate, a highly transparent perovskite-type transparent potassium niobate thin film can be produced.

In the present invention, as the amorphous substrate, an alkaline earth metal such as Ba, Sr, Ca or Mg, L
a rare earth element such as a, Y, Gd or Yb, or a glass substrate containing at least one element selected from Bi, Pb and Nb is used,
A (110) -oriented perovskite-type transparent potassium niobate thin film can be formed thereon. As such a glass substrate, for example, SiO ₂ —Al ₂ O ₃ —B
aO-B ₂ O ₃ type glass, SiO ₂ -Al ₂ O ₃ -BaO-
CaO-based _{glass, SiO 2 -Al 2 O 3 -BaO} -SrO
System _{glass, SiO 2 -Al 2 O 3 -CaO} -La 2 O 3 based _{glass, SiO 2 -Al 2 O 3 -BaO} -B 2 O 3 -Bi 2 O 3
System _{glass, SiO 2 -Al 2 O 3 -BaO} -PbO based _{glass, SiO 2 -Al 2 O 3 -BaO} -MgO based glass, S
_{iO 2 -Al 2 O 3 -B 2} O 3 may be mentioned glass substrate such -Nb ₂ O ₅ based glass. By using such a glass substrate, a highly transparent (110) -oriented perovskite-type transparent potassium niobate thin film having high transparency can be produced. By using a perovskite-type transparent potassium niobate thin film having a (110) orientation, a high-performance optical element can be manufactured using the potassium niobate thin film. In the present invention, among all the oxides forming the glass substrate, alkaline earth metals such as Ba, Sr, Ca and Mg, rare earths such as La, Y, Gd and Yb, and Bi, Pb, Nb and Co. , Ni, and W account for the total proportion of oxides, which is preferably 0.01 to 70 mol%, and more preferably 1.0 to 50 mol%. This ratio is, for example, SiO ₂ —Al ₂ O ₃ —Ba.
For OB ₂ O ₃ based glass, BaO / (SiO ₂ +
Al ₂ O ₃ + BaO + B ₂ O ₃ ), which is the molar ratio calculated, and for SiO ₂ —Al ₂ O ₃ —CaO—La ₂ O ₃ system glass, (CaO + La ₂ O ₃ ) / (SiO ₂ + Al ₂
It is the molar ratio calculated as O ₃ + CaO + La ₂ O ₃ ). Of all the oxides that form the glass substrate, B
a, Sr, Ca, Mg and other alkaline earth metals, La,
Rare earth elements such as Y, Gd and Yb, and Bi, Pb and Nb,
The total ratio of the oxides of Co, Ni and W is 0.0
If it is less than 1 mol% or more than 70 mol%, a highly transparent perovskite-type potassium niobate thin film may not be obtained. Further, by adjusting the ratio of each element of the glass substrate, the (110) orientation of the perovskite-type transparent potassium niobate thin film and the crystal grain size can be controlled.

In the present invention, B is formed on a crystalline, amorphous or composite substrate of these as an amorphous substrate.
a, Sr, Ca, Mg and other alkaline earth metals, La,
Rare earth elements such as Y, Gd, Yb, Bi, Pb, Nb, C
A composite amorphous substrate having an amorphous layer containing at least one element selected from o, Ni, and W can be used. The substrate for forming the amorphous layer is not particularly limited, and any substrate can be used as long as it supports the amorphous layer and satisfies the physical properties such as heat resistance to withstand the production of the amorphous layer and the potassium niobate thin film. As a crystal substrate used for making a composite amorphous substrate,
For example, alumina, silicon, platinum, gallium-arsenic,
A mullite substrate etc. can be mentioned. As the amorphous substrate used to make the composite amorphous substrate,
For example, quartz glass, borosilicate glass substrate, etc. can be mentioned. Examples of the composite substrate used for producing the composite amorphous substrate include a glass-ceramic composite substrate and a ceramic-metal composite (cermet) substrate. Examples of the amorphous layer formed on the crystal, amorphous or composite substrate thereof include SiO ₂ —Al ₂ O ₃ —BaO—B ₂ O ₃ system amorphous layer, SiO ₂ —Al ₂ O ₃ —BaO—CaO system. amorphous _{layer, SiO 2 -Al 2 O 3 -BaO} -SrO
System amorphous _{layer, SiO 2 -Al 2 O 3 -CaO} -La 2
O ₃ based amorphous _{layer, SiO 2 -Al 2 O 3 -BaO} -B
₂ O ₃ -Bi ₂ O ₃ based amorphous layer, SiO ₂ -Al ₂ O ₃
-BaO-PbO-based amorphous layer, SiO ₂ -Al ₂ O
₃ -BaO-MgO-based amorphous layer, SiO ₂ -Al ₂
O ₃ -B ₂ O ₃ -CoO based amorphous layer, SiO ₂ -Al
_{2 O 3 -B 2 O 3 -Nb} 2 O 5 based amorphous layer, SiO ₂ -
_{Al 2 O 3 -B 2 O 3} -NiO -based amorphous layer, SiO _{2
-Al 2 O 3 -B 2 O 3} -WO 3 based amorphous layer, BaO
-SiO ₂ based amorphous layer, SrO-SiO ₂ type amorphous layer, La ₂ O ₃ -SiO ₂ based amorphous layer, Sr
O-Al ₂ O ₃ based amorphous layer, Bi ₂ O ₃ -SiO ₂ based amorphous layer, and the like ZrO ₂ -BaO-La ₂ O ₃ based amorphous layer. By using the composite amorphous substrate on which such an amorphous layer is formed, a highly transparent perovskite-type transparent potassium niobate thin film can be produced.

In the present invention, B is formed on a crystalline, amorphous or composite substrate of these as an amorphous substrate.
a, Sr, Ca, Mg and other alkaline earth metals, La,
A composite amorphous substrate having an amorphous layer containing a rare earth element such as Y, Gd, and Yb and at least one element selected from Bi, Pb, and Nb is used, and (110) -oriented perovskite-type transparent potassium niobate is used. Thin films can be made. The substrate for forming the amorphous layer is not particularly limited, and any substrate can be used as long as it supports the amorphous layer and satisfies the physical properties such as heat resistance to withstand the production of the amorphous layer and the potassium niobate thin film. Examples of the crystal substrate used for producing the composite amorphous substrate include alumina, silicon, platinum, gallium-arsenic, and mullite substrate. Examples of the amorphous substrate used for producing the composite amorphous substrate include a quartz glass substrate and a borosilicate glass substrate. Examples of the composite substrate used for producing the composite amorphous substrate include a glass-ceramic composite substrate and a ceramic-metal composite (cermet) substrate. Examples of the amorphous layer formed on a crystalline, amorphous or composite substrate of these include SiO ₂ —Al ₂ O ₃ —BaO—B ₂ O.
₃ based amorphous _{layer, SiO 2 -Al 2 O 3 -BaO} -Ca
O amorphous _{layer, SiO 2 -Al 2 O 3 -BaO} -S
rO-based amorphous layer, SiO ₂ -Al ₂ O ₃ -CaO-
La ₂ O ₃ based amorphous layer, SiO ₂ -Al ₂ O ₃ -Ba
_{O-B 2 O 3 -Bi 2} O 3 based amorphous layer, SiO ₂ -A
l ₂ O ₃ —BaO—PbO based amorphous layer, SiO ₂ −
Al ₂ O ₃ —BaO—MgO based amorphous layer, SiO _{2
-Al 2 O 3 -B 2 O 3} -Nb 2 O 5 based amorphous layer, Ba
O-SiO ₂ based amorphous layer, SrO-SiO ₂ type amorphous layer, La ₂ O ₃ -SiO ₂ based amorphous layer, S
rO-Al ₂ O ₃ based amorphous layer, Bi ₂ O ₃ -SiO ₂
Examples thereof include a system amorphous layer and a ZrO ₂ —BaO—La ₂ O ₃ system amorphous layer. By forming a potassium niobate thin film on such an amorphous layer, a highly transparent and strongly (110) -oriented perovskite-type transparent potassium niobate thin film can be prepared. By using a perovskite-type transparent potassium niobate thin film having a (110) orientation, a high-performance optical element can be manufactured using the potassium niobate thin film.

In the present invention, among all the oxides forming the amorphous layer, alkaline earth metals such as Ba, Sr, Ca and Mg, rare earth elements such as La, Y, Gd and Yb, and Bi, Pb, The total proportion of oxides of Nb, Co, Ni, and W is preferably 0.01 to 70 mol%, more preferably 1.0 to 50 mol%. This ratio is, for example, SiO ₂ —Al ₂ O ₃ —B ₂
O ₃ for -Nb ₂ O ₅ based amorphous layer, Nb ₂ O ₅
/ Is the molar ratio calculated as _{(SiO 2 + Al 2 O 3} + B 2 O 3 + Nb 2 O 5), for the ZrO ₂ -BaO-La ₂ O ₃ based amorphous _{layer, (BaO + La 2 O 3} ) /
It is the molar ratio calculated as (ZrO ₂ + BaO + La ₂ O ₃ ). Among all the oxides forming the amorphous layer, alkaline earth metals such as Ba, Sr, Ca, and Mg, rare earth metals such as La, Y, Gd, and Yb, and Bi and P
A perovskite-type potassium niobate thin film having high transparency can be obtained even if the total proportion of oxides of b, Nb, Co, Ni and W is less than 0.01 mol% or more than 70 mol%. There is a possibility that there is no. Further, by adjusting the ratio of each element in the amorphous layer, the (110) orientation of the perovskite-type transparent potassium niobate thin film and the crystal grain size can be controlled. In the present invention, the thickness of the amorphous layer of the composite amorphous substrate is preferably 1 nm or more, more preferably 10 nm or more. In the present invention, there is no particular limitation on the method for forming the amorphous layer on the crystalline, amorphous or composite substrate thereof, and for example, P method such as sputtering method is used.
VD method (physical vapor deposition method), sol-gel method with or without metal alkoxide, plasma CVD method and thermal CV
A CVD method (chemical vapor deposition method) such as D method, an LPD method (liquid phase deposition method), a thick film printing method, or the like can be used. Further, in addition to directly forming an amorphous layer of a desired composition containing an effective element by the above method, on a glass substrate containing no effective element or on an amorphous layer containing no effective element of a composite amorphous substrate, a sputtering method, etc. PVD
Method, sol with or without metal alkoxide
The oxide thin film or metal thin film of the effective element is formed into a very thin or discontinuous island shape by a method such as a gel method, a plasma CVD method or a CVD method such as a thermal CVD method, and the effective element is contained by thermal diffusion. It is also possible to form an amorphous layer having a desired composition.

In the present invention, the amorphous substrate is
It may have a fine groove or a protruding pattern. When the amorphous substrate is a glass substrate, wet etching using hydrofluoric acid-ammonium fluoride aqueous solution or hydrofluoric acid-ammonium fluoride aqueous solution-sulfuric acid, sputter etching using argon ion, etc. Patterning can be performed by reactive etching using fluorocarbon, fluoroform, or the like. In addition, a patterned metal electrode is formed on a crystalline, amorphous or composite substrate of these,
By forming an amorphous layer on the substrate having the pattern, a composite amorphous substrate having a fine projecting pattern can be obtained. Further, an amorphous layer is formed on a crystal, amorphous, or composite substrate thereof having a fine groove or projecting pattern formed by etching or the like to obtain a composite amorphous substrate having a fine groove or projecting pattern. You can An optical element can be easily obtained by forming a perovskite-type transparent potassium niobate thin film in accordance with the pattern, because the amorphous substrate has fine grooves or projecting patterns. Further, after forming a perovskite-type transparent potassium niobate thin film on an amorphous substrate, it is possible to pattern the perovskite-type transparent potassium niobate thin film by sputter etching using argon ions or the like,
An optical element such as an optical waveguide can be easily obtained. Since potassium niobate is transparent in the wavelength range of about 0.4 to about 4.5 μm and hardly absorbs light in the visible to near-infrared wavelength range, incident light and SHG light can be propagated with low loss. it can. Furthermore, since potassium niobate has a very large nonlinear optical effect or electro-optical effect, a thin optical element such as a thin film SHG element capable of efficiently performing wavelength conversion into blue or green or a waveguide type optical switching element or the like. Can be used as

[0012]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. Example 1 As an amorphous substrate, SiO ₂ —BaO—Al ₂ O _{3 was used.}
-B ₂ O ₃ based glass (Corning # 7059 glass)
Using a substrate, a target in which a mixed powder of KNbO ₃ and K ₂ CO ₃ (molar ratio 1: 1) was deposited on quartz glass, an argon gas partial pressure of 0.36 Pa and an oxygen partial pressure of 0.3. 0
High-frequency magnetron sputtering was performed under the conditions of 4 Pa, substrate temperature of 500 ° C., high-frequency power of 50 W, and film formation time of 10 hours to produce a perovskite-type transparent potassium niobate thin film. The film thickness was about 900 nm. FIG.
It is an XRD pattern measured using CuKα ray of this potassium niobate thin film. From this figure, it was found that this perovskite-type transparent potassium niobate thin film had a strong (110) orientation. The prepared potassium niobate thin film was subjected to a prism coupling method to generate H having a wavelength of 633 nm.
The e-Ne laser was able to enter and propagate.
Further, when a cross section was polished and a semiconductor laser having a wavelength of 860 nm was made incident on the film from the cross section, blue SHG light could be generated. Example 2 Amorphous substrate having a thickness of about 50 nm on silicon
CoO-SiO ₂ based amorphous layer of CoO and S
Using a mixed powder of iO ₂ (molar ratio 1: 5) target, argon gas partial pressure 0.72 Pa, oxygen partial pressure 0.08 P
a, substrate temperature 300 ° C., high frequency power 50 W, film formation time 1
Under the condition of 5 minutes, a composite amorphous substrate formed by a high frequency magnetron sputtering method is used, on which a mixed powder of KNbO ₃ and K ₂ CO ₃ (molar ratio 1: 1) is used.
RF magnetron sputtering under the conditions of an argon gas partial pressure of 0.36 Pa, an oxygen partial pressure of 0.04 Pa, a substrate temperature of 500 ° C., a high frequency power of 50 W, and a film forming time of 3 hours using a target deposited on quartz glass. Then, a perovskite-type transparent potassium niobate thin film having a film thickness of about 350 nm was prepared. Example 3 An amorphous substrate having a thickness of about 300 n on silicon
m of BaO—SiO ₂ amorphous layer with BaCO ₃
Argon gas partial pressure 0.72 Pa and oxygen partial pressure 0.7 using a mixed powder of SiO and SiO ₂ (molar ratio 1:20) target.
A composite amorphous substrate formed by a high frequency magnetron sputtering method was produced under the conditions of 08 Pa, substrate temperature of 300 ° C., high frequency power of 50 W, and film formation time of 1 hour.
BaO / (BaO + SiO ₂ ) of this amorphous layer
The (molar ratio) was 0.05. Using this composite amorphous substrate, a mixed powder of KNbO ₃ and K ₂ CO ₃ (molar ratio 1: 1) was deposited on the quartz glass, and a partial pressure of argon gas of 0.36 Pa was used. , Oxygen partial pressure 0.04Pa, substrate temperature 500 ℃, high frequency power 5
High-frequency magnetron sputtering was performed under the conditions of 0 W and a film forming time of 3 hours to prepare a perovskite-type transparent potassium niobate thin film having a film thickness of about 350 nm. The ratio of (110) peak intensity / (111) peak intensity obtained from the XRD pattern was about 10,000, and it was found that this potassium niobate thin film was strongly (110) oriented. The crystal grain size of this potassium niobate thin film was about 0.23 μm when examined by an atomic force microscope.
Further, by changing the mixing ratio of BaCO ₃ and SiO ₂ powder, BaO / (BaO + SiO ₂ ) (molar ratio) was 0.0 by the high frequency magnetron sputtering method under the same conditions as above.
Four types of composite amorphous substrates having amorphous layers of 1, 0.02, 0.09 and 0.17 were produced, and high frequency magnetron sputtering was performed in the same manner to produce a perovskite type transparent potassium niobate thin film. FIG. 2 shows the ratio of (110) peak intensity / (111) peak intensity obtained from the XRD pattern and the crystal grain size obtained by an atomic force microscope. From this figure, the amorphous layer B
It can be seen that the (110) orientation of the potassium niobate film and the crystal grain size can be controlled by changing the ratio of aO to BaO + SiO ₂ . Example 4 As an amorphous substrate, a thickness of about 10 was formed on silica glass.
A 0 nm ZrO ₂ —BaO—La ₂ O ₃ -based amorphous layer (ZrO ₂ : BaO: La ₂ O ₃ = 40: 2: 1, molar ratio) was used as Zr (OCH ₂ CH ₂ CH ₃ ) ₄ and Ba metal. , CH ₃
OCH ₂ CH ₂ OH, La (OCH ₂ CH ₂ OCH ₃ ) ₃ was used as a raw material, and a composite amorphous substrate formed by a sol-gel method was used, on which a mixed powder of KNbO ₃ and K ₂ CO ₃ (mol Using a target having a ratio of 1: 1) deposited on quartz glass, argon gas partial pressure 0.36 Pa, oxygen partial pressure 0.04 Pa, substrate temperature 500 ° C., high-frequency power 50
High-frequency magnetron sputtering was performed under the conditions of W and a film formation time of 3 hours to prepare a (110) -oriented perovskite-type transparent potassium niobate thin film having a film thickness of about 350 nm. Example 5 As an amorphous substrate, SiO ₂ —BaO—SrO—CaO—A having a thickness of about 100 μm was formed on an alumina ceramic.
l ₂ O ₃ -La ₂ O ₃ -based amorphous layer, SiO ₂ -B
Total _{aO-SrO-CaO-Al 2} O 3 -La 2 O 3 based glass paste (alkaline earth metal oxides and La ₂ O ₃ 27
Mol%) screen-printed and baked to use a composite amorphous substrate on which KNbO ₃ and K ₂ CO
Argon gas partial pressure was 0.36 using a target in which the mixed powder of ₃ (1: 1 in molar ratio) was deposited on quartz glass.
High-frequency magnetron sputtering was performed under the conditions of Pa, oxygen partial pressure of 0.04 Pa, substrate temperature of 500 ° C., high-frequency power of 50 W, and film formation time of 3 hours to obtain a film thickness of about 350 nm (1
10) An oriented perovskite-type transparent potassium niobate thin film was prepared. Example 6 As an amorphous substrate, SiO ₂ —BaO—Al ₂ O _{3 was used.}
-B ₂ O ₃ based glass (Corning # 7059 glass)
The substrate was wet-etched using a mixed solution (volume mixing ratio 49: 49: 2) of hydrofluoric acid (concentration 50% by weight) -ammonium fluoride aqueous solution (concentration 40% by weight) -sulfuric acid (concentration 97% by weight). , Width about 50μm, depth about 0.5μ
Using a substrate having a groove of m patterned, a mixed powder of KNbO ₃ and K ₂ CO ₃ (molar ratio of 1: 1) is deposited on the quartz glass on the substrate having the groove patterned. , Argon gas partial pressure 0.36Pa, oxygen partial pressure 0.04Pa, substrate temperature 500 ° C, high frequency power 50
High-frequency magnetron sputtering was performed under the conditions of W and a film formation time of 3 hours to prepare a (110) -oriented perovskite-type transparent potassium niobate thin film having a film thickness of about 350 nm. Example 7 As an amorphous substrate, a SiO ₂ glass substrate was wet-etched using a mixed solution (volume mixing ratio 1: 1) of hydrofluoric acid (concentration 50% by weight) -ammonium fluoride aqueous solution (concentration 40% by weight). , Width about 50 μm, depth 0.
A 5 μm groove was patterned, and a PbO—SiO ₂ -based amorphous layer having a thickness of about 80 nm was formed on a substrate on which the groove was patterned using a mixed powder of PbO and SiO ₂ (molar ratio 1: 5) as a target. Gas partial pressure 0.7
A composite amorphous substrate formed by a high frequency magnetron sputtering method was used under the conditions of 2 Pa, oxygen partial pressure of 0.08 Pa, substrate temperature of 300 ° C., high frequency power of 50 W, and film formation time of 15 minutes, and KNbO ₃ and K ₂ were further formed thereon. C
Argon gas partial pressure was 0.3 using a target in which a mixed powder of O ₃ (molar ratio 1: 1) was deposited on quartz glass.
High-frequency magnetron sputtering was performed under the conditions of 6 Pa, oxygen partial pressure of 0.04 Pa, substrate temperature of 500 ° C., high-frequency power of 50 W, and film formation time of 3 hours to form a (110) -oriented transparent perovskite-type transparent potassium niobate thin film having a thickness of about 350 nm. Was produced. Example 8 As an amorphous substrate, an SrO layer was formed on a quartz glass by S.
using RCO ₃ powder target, an argon gas partial pressure 0.
72 Pa, oxygen partial pressure 0.08 Pa, substrate temperature room temperature, high-frequency power 50 W, film formation time 60 seconds, formed by a high-frequency magnetron sputtering method, and thermally diffused at 500 ° C. for 2 hours to form SrO—SiO _{2 on the} surface. Using a composite amorphous substrate on which a system amorphous layer is formed, and using a target in which a mixed powder of KNbO ₃ and K ₂ CO ₃ (molar ratio 1: 1) is deposited on quartz glass, an argon gas is used. Partial pressure 0.36 Pa, oxygen partial pressure 0.04
High-frequency magnetron sputtering was performed under the conditions of Pa, substrate temperature of 500 ° C., high-frequency power of 50 W, and film formation time of 3 hours to prepare a (110) -oriented perovskite-type transparent potassium niobate thin film having a film thickness of about 350 nm. Examples 9 to 24 A method similar to that of Example 2 (however, the film formation time of the amorphous layer was 1 minute in Example 9 and 1 hour in Example 11).
Then, a composite amorphous substrate having the amorphous layer shown in Table 1 was prepared, and a potassium niobate thin film was prepared thereon. Regarding the obtained potassium niobate thin film, the transparency and crystal structure of the thin film were examined, and in the case of the perovskite type, the (110) orientation was examined. The results are shown in Table 1. The film thickness of the potassium niobate thin film is about 350 in each case.
nm. Comparative Examples 1 to 3 In the same manner as in Example 2 (however, the amorphous layer was not formed), potassium niobate thin films were prepared using the substrates shown in Table 2. Regarding the obtained potassium niobate thin film, the transparency and crystal structure of the thin film were examined, and in the case of the perovskite type, the (110) orientation was examined. The results are shown in Table 2.

[0013]

[Table 1]

[0014]

[Table 2]

The potassium niobate thin films of Examples 9 to 24 of the present invention were all perovskite type crystals. The potassium niobate thin films of Examples 9 to 22 were strongly (110) oriented and transparent. The potassium niobate thin films of Examples 23 and 24 were transparent although the (110) orientation was not strong. On the other hand, the potassium niobate thin film prepared on the (100) Si single crystal substrate of Comparative Example 1 was a perovskite type crystal, but it was not transparent but (11
0) The orientation was not strong either. The potassium niobate thin film prepared on the platinum substrate of Comparative Example 2 was also a perovskite type crystal, but it was not transparent and the (110) orientation was not strong. The potassium niobate thin film prepared on the SUS304 substrate of Comparative Example 3 was neither a perovskite type crystal nor transparent.

[0016]

The potassium niobate thin film of the present invention is a perovskite type potassium niobate thin film on an amorphous substrate, is excellent in transparency and can be (110) oriented, and the amorphous substrate has a selected refractive index. Since the area is wide, it can be used for optical elements such as an optical waveguide element, an SHG element, and an optical switching element.

[Brief description of the drawings]

FIG. 1 is an XR of a potassium niobate thin film of the present invention.
It is a D pattern.

FIG. 2 was obtained from an XRD pattern (110).
It is a graph which shows the ratio of peak intensity / (111) peak intensity and the crystal grain size calculated by the atomic force microscope.

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Claims (20)

[Claims] 1. A perovskite-type transparent potassium niobate thin film formed on an amorphous substrate. 2. A thin film formed on an amorphous substrate,
The perovskite-type transparent potassium niobate thin film according to claim 1, which has a (110) orientation. 3. The amorphous substrate is an alkaline earth metal,
The perovskite-type transparent potassium niobate thin film according to claim 1, which is a glass substrate containing at least one element selected from the group consisting of rare earth elements, Bi, Pb, Nb, Co, Ni, and W. 4. The amorphous substrate is an alkaline earth metal,
The perovskite-type transparent potassium niobate thin film according to claim 2, which is a glass substrate containing at least one element selected from rare earth elements, Bi, Pb, and Nb. 5. An amorphous layer in which an amorphous substrate contains at least one element selected from alkaline earth metals, rare earths, Bi, Pb, Nb, Co, Ni and W on a crystalline, amorphous or composite substrate thereof. The perovskite-type transparent potassium niobate thin film according to claim 1, which is a composite amorphous substrate having formed therein. 6. A composite amorphous substrate in which an amorphous substrate is a crystal, an amorphous or a composite substrate thereof, on which an amorphous layer containing at least one element selected from alkaline earth metals, rare earths, Bi, Pb and Nb is formed. The perovskite-type transparent potassium niobate thin film according to claim 2. 7. The perovskite-type transparent potassium niobate thin film according to claim 3 or 4, wherein the glass substrate has a fine groove or a projecting pattern. 8. A composite amorphous substrate has a fine projecting pattern formed by patterning a metal electrode on a crystalline, amorphous or composite substrate of these, and an amorphous layer is formed on the substrate having the pattern. The perovskite-type transparent potassium niobate thin film according to claim 5 or 6. 9. The composite amorphous substrate is obtained by forming an amorphous layer on a crystal, amorphous or composite substrate of these having fine grooves or protruding patterns.
Alternatively, the perovskite-type transparent potassium niobate thin film according to claim 6. 10. A method for producing a perovskite-type transparent potassium niobate thin film, which is produced on an amorphous substrate by a PVD method. 11. The method for producing a perovskite-type transparent potassium niobate thin film according to claim 10, wherein the PVD method is a sputtering method. 12. A thin film formed on an amorphous substrate,
The method for producing a perovskite-type transparent potassium niobate thin film according to claim 10 or 11, which has a (110) orientation. 13. The amorphous substrate is a glass substrate containing at least one element selected from alkaline earth metals, rare earths, Bi, Pb, Nb, Co, Ni and W.
0 or the method for producing a perovskite-type transparent potassium niobate thin film according to claim 11. 14. The method for producing a perovskite-type transparent potassium niobate thin film according to claim 12, wherein the amorphous substrate is a glass substrate containing at least one element selected from alkaline earth metals, rare earths, Bi, Pb and Nb. . 15. Alkaline earth metal, rare earth, Bi, Pb, N on a crystalline, amorphous or composite substrate thereof.
PVD method, sol-gel method, CVD method, an amorphous layer containing at least one element of b, Co, Ni and W,
The method for producing a perovskite-type transparent potassium niobate thin film according to claim 10 or 11, which is produced on a composite amorphous substrate formed by any one of the LPD method and the thick film printing method. 16. Alkaline earth metal, rare earth, Bi, Pb, N on a crystal, amorphous or composite substrate thereof.
An amorphous layer containing at least one element of b is formed on a composite amorphous substrate formed by any one of PVD method, sol-gel method, CVD method, LPD method and thick film printing method. Item 13. A method for producing a perovskite-type transparent potassium niobate thin film according to Item 12. 17. An optical element using the perovskite type transparent potassium niobate thin film formed on the amorphous substrate according to claim 1. Description: 18. The optical element is an optical waveguide element.
7. The optical element according to 7. 19. The optical element is an SHG element.
The optical element described. 20. The optical element according to claim 17, wherein the optical element is an optical switching element.