WO2010038788A1 - Current control element and method for manufacturing the current control element - Google Patents

Abstract

Disclosed is a current control element that can realize current control with a lower drive power.  Also disclosed is a method for manufacturing the current control element. The current control element comprises a current controller that controls the amount of current by applying an electric field, and an electrode that applies a predetermined electric field to the current controller.  The current controller is formed of a compound having a layered triangle lattice structure containing a rare earth element.  In particular, the current controller is formed of a compound having a layered triangle lattice structure represented by (RMbO3-d)n(MaO)m wherein R represents at least one element selected from In, Sc, Y, Dy, Ho, Er, Tm, Yb, Lu, Ti, Ca, Sr, Ce, Sn, and Hf; Ma and Mb, which may be same or different, represent at least one element selected from Ti, Mn, Fe, Co, Cu, Ga, Zn, Al, Mg, and Cd; n is an integer of 1 or more; m is an integer of 0 or more; and d is a real number of 0 to 0.2.  Alternatively, the current controller may be formed of a compound that is the same compound as described above except that a part of R in the compound has been replaced with a positive divalent or lower element.

Description

Current control element and manufacturing method thereof

The present invention relates to a current control element capable of controlling the amount of current by applying a predetermined electric field, and a manufacturing method thereof.

Conventionally, in a semiconductor element, a p-type semiconductor layer, an n-type semiconductor layer, an insulating layer, and the like are used to form a transistor, a diode, and the like, and a required semiconductor circuit is formed using these elements.

In particular, a transistor in a semiconductor circuit is often used as a switching element that performs on / off switching control of energization.

A transistor is generally formed by joining a p-type semiconductor layer and an n-type semiconductor layer, and has a pn junction in which a p-type semiconductor layer and an n-type semiconductor layer are joined. The transistor cannot be driven unless energy exceeding the energy band gap generated at the pn junction is given.

Therefore, a transistor in a semiconductor circuit formed using silicon requires a driving voltage of at least 0.7 V or more, and normally a voltage of about 1.5 V or more is required to stably operate the semiconductor circuit. It is often applied.

Furthermore, in semiconductor circuits, power is consumed during operation and heat is generated. Therefore, not only to save power, but also to suppress the amount of heat generated, semiconductor circuits are required to be driven at as low a voltage as possible. Yes.

Therefore, a phase change layer composed of vanadium oxide, nickel oxide, hafnium oxide or the like is provided, and the physical properties of the channel are changed by utilizing the fact that this phase change layer changes its conductivity when a voltage is applied. A method for controlling and lowering the driving voltage of a semiconductor circuit has been proposed (for example, see Patent Document 1).
JP 2006-1148109 A

However, it is not sufficient to control the physical properties of the channel with the phase change layer, and the manufacturing cost may increase due to the complicated structure.

While conducting research on a compound having a layered triangular lattice structure containing rare earth elements, the present inventors provide a current control element capable of current control with a small driving voltage by utilizing the current-carrying characteristics of this compound. The present invention has been accomplished by thinking of what can be done.

The current control element of the present invention is a current control element that includes a current control body that controls the amount of current by applying an electric field, and an electrode that applies a predetermined electric field to the current control body. It was decided to comprise a compound having a layered triangular lattice structure containing the element.

Furthermore, the current control element of the present invention is also characterized by the following points. That is,
(1) In the compound, R is at least one element selected from In, Sc, Y, Dy, Ho, Er, Tm, Yb, Lu, Ti, Ca, Sr, Ce, Sn, and Hf, Ma, and Mb is at least one element selected from Ti, Mn, Fe, Co, Cu, Ga, Zn, Al, Mg, and Cd, n is an integer of 1 or more, m is an integer of 0 or more, δ Is a compound represented by (RMbO _3-δ ) _n (MaO) _m , where R is a real number of 0 or more and 0.2 or less, or a compound in which a part of R of the compound is substituted with an element less than or equal to positive divalent.
(2) The current control body is joined between the drain electrode and the source electrode of the p-type conductor provided with the drain electrode and the source electrode.
(3) The current control body is provided with an input side electrode for inputting current and an output side electrode for outputting current.
(4) The direction of the electric field applied to the current control body is the c-axis direction of the compound portion.

The current control element manufacturing method of the present invention is a current control element manufacturing method including a current control body that controls the amount of current by applying an electric field, and an electrode that applies a predetermined electric field to the current control body. Therefore, the method includes forming the current control body with a compound having a layered triangular lattice structure containing a rare earth element.

In the present invention, a current control body of a current control element having a current control body that controls the amount of current by applying an electric field and an electrode that causes a predetermined electric field to act on the current control body is formed into a layered triangle containing a rare earth element. By forming with a compound having a lattice structure, a current control element that is driven at a voltage lower than 0.7 V can be provided, and a current control element that saves power and generates low heat can be provided.

FIG. 1 is a schematic explanatory diagram of the arrangement of each element in a plan view of a compound having a layered triangular lattice structure. FIG. 2 is a schematic explanatory diagram of the arrangement of each element in a side view of a compound having a layered triangular lattice structure. FIG. 3 is an explanatory diagram of the current control element of the first embodiment. FIG. 4 is a graph of the current-voltage measurement result of the pn junction formed by the current control body and the p-type conductor. FIG. 5 is an explanatory diagram of the current control element of the second embodiment. FIG. 6 is an explanatory diagram of a current control element according to the third embodiment. FIG. 7 is an explanatory diagram of a modification example of the current control element of the third embodiment. FIG. 8 is an explanatory diagram of a modification example of the current control element of the third embodiment.

10 p-type conductor 11 drain electrode 12 source electrode 13 current controller 14 gate electrode

In the current control element and the manufacturing method thereof according to the present invention, in the current control element having a current control body that controls the amount of current by applying an electric field, and an electrode that applies a predetermined electric field to the current control body, the current control body Is formed of a compound having a layered triangular lattice structure containing a rare earth element.

Specifically, the current control body includes at least one element selected from R, In, Sc, Y, Dy, Ho, Er, Tm, Yb, Lu, Ti, Ca, Sr, Ce, Sn, and Hf. , Ma and Mb are at least one element selected from Ti, Mn, Fe, Co, Cu, Ga, Zn, Al, Mg, and Cd, n is an integer of 1 or more, and m is 0 or more. It is a compound represented by (RMbO _{3 -δ} ) _n (MaO) _m , where R is an integer and δ is a real number of 0 or more and 0.2 or less, or a compound in which a part of R of the compound is substituted with an element less than or equal to positive divalent.

Hereinafter, a compound having a layered triangular lattice structure will be described with LuFe ₂ O _{4 in} which R is Lu and Ma and Mb are Fe as representative examples.

LuFe ₂ O ₄ can be produced by the following procedure.
(1) Lutetium oxide (Lu ₂ O ₃ ) and iron (III) oxide (Fe ₂ O ₃ ) are mixed at a ratio of 1: 2 and mixed with a ball mill for about 1 hour to form a mixture.
(2) The mixture is formed into a predetermined shape and heated to 800 ° C. for 24 hours in an oxygen atmosphere to form a pre-fired body.
(3) The temporary fired body is fired by the FZ (Floating Zone) method to obtain single crystal LuFe ₂ O ₄ . At this time, the crystal is grown in an atmosphere of a CO—CO ₂ mixed gas that is a mixed gas of carbon monoxide and carbon dioxide.

In the main firing for producing a single crystal, a CO ₂ —H ₂ mixed gas may be used instead of the CO—CO ₂ mixed gas, and the amount of oxygen is obtained by firing while controlling the oxygen partial pressure in a reducing atmosphere. Is adjusted.

The crystal structure of single crystal LuFe ₂ O ₄ will be described with reference to FIGS. For convenience of explanation, the crystal structure of LuFe ₂ O ₄ is in a state before so-called charge ordering, in which the ordered structure of Fe ³⁺ and Fe ²⁺ does not appear in Fe ions in the crystal.

FIG. 1 is a schematic explanatory diagram of the arrangement of each element in a plan view, and shows the positional relationship of a triangular lattice of element A, a triangular lattice of element B, and a triangular lattice of element C. In the following, the position of the lattice point in the triangular lattice of element A is “A position”, the position of the lattice point in the triangular lattice of element B is “B position”, and the position of the lattice point in the triangular lattice of element C is “C position”. I will call it.

FIG. 2 is a schematic explanatory diagram of the arrangement of each element in a side view, and each element is located at a predetermined position in the following order from the uppermost layer downward.
Lu-B position O-C position Fe-C position O-B position O-C position Fe-B position O-B position Lu-C position O-A position Fe-A position ○
O-C position ○
O-A position ○
Fe-C position ○
O-C position Lu-A position O-B position Fe-B position O-A position O-B position Fe-A position O-A position Lu-B position

Among these, a portion composed of four layers marked with a circle is called a W layer (W-Layer), and having this W layer is a characteristic point of LuFe ₂ O ₄ .

Further, it is known that a W layer is also formed in a compound having a layered triangular lattice structure other than LuFe ₂ O ₄ .

The W layer has a triangular lattice laminated structure, and the presence of the same number of Fe ²⁺ and Fe ³⁺ in LuFe ₂ O ₄ causes frustration of charges.

As a result, in LuFe ₂ O ₄ , the region rich in Fe ³⁺ has a role of positive charge in the W layer, while the region rich in Fe ²⁺ has a role of negative charge. (Electrical polarization) appears.

In addition, in LuFe ₂ O ₄ , the electric dipole state is changed by applying an electric field from the outside, and the conductivity changes, so that the amount of current flowing through LuFe ₂ O ₄ can be changed.

Thus, a compound having a layered triangular lattice structure containing a rare earth element has a W layer and can change the amount of current by an electric field applied from the outside, so that it can be used as a current control element.

The following will be described in detail based on the drawings.

[First Embodiment]
As shown in FIG. 3, the current control element according to the first embodiment includes a p-type conductor 10 serving as a support base, a drain electrode 11 and a source electrode 12 provided at predetermined positions of the p-type conductor 10, A current control body 13 provided on the upper surface of the p-type conductor 10 between the drain electrode 11 and the source electrode 12 and a gate electrode 14 provided on the upper surface of the current control body 13 are configured.

In the present embodiment, the current control body 13 is LuFe ₂ O ₄ . The current control body 13 is not limited to LuFe ₂ O ₄ , and R is changed to In, Sc, Y, Dy, Ho, Er, Tm, Yb, Lu, Ti, Ca, Sr, Ce, Sn, Hf. At least one element selected from the group consisting of Ma, Mb, at least one element selected from Ti, Mn, Fe, Co, Cu, Ga, Zn, Al, Mg, and Cd, n being one or more Or a compound having a layered triangular lattice structure represented by (RMbO3 _-δ ) _n (MaO) _m , where m is an integer of 0 or more and δ is a real number of 0 or more and 0.2 or less, or one of R of the compound A compound in which a part is substituted with an element having a positive divalent value or less can be used. Hereinafter, the current control body 13 will be described as LuFe ₂ O ₄ .

LuFe ₂ O ₄ functions as an n-type conductor, and is provided in contact with the p-type conductor 10 so that the junction interface between the p-type conductor 10 and the current control body 13 is a pn junction interface.

As the p-type conductor 10, an appropriate semiconductor can be used. However, when the p-type conductor 10 is an organic semiconductor composed of C60 fullerene, it exhibits rectification characteristics as shown in FIG. It is confirmed that it is formed.

When the p-type conductor 10 is an organic semiconductor composed of C60 fullerene, the p-type conductor 10 is formed by vacuum-depositing C60 fullerene on an appropriate support base.

When a positive electric field is applied to the gate electrode 14 in a current control element in which a pn junction interface is formed by the p-type conductor 10 and the current control body 13, the junction interface portion between the p-type conductor 10 and the current control body 13 becomes negative. Charges appear, and the negative charges trap carriers, thereby reducing electrical conduction between the source and drain electrodes. That is, the current control element of this embodiment functions as a transistor that performs current control.

The current control body 13 may be a single crystal of LuFe ₂ O ₄ or may be polycrystalline, but when it is a single crystal, it is sandwiched between the p-type conductor 10 and the gate electrode 14. By controlling the thickness direction of the current control body 13 to the c-axis direction of LuFe ₂ O ₄ , current control can be performed effectively.

The current control element of the first embodiment is formed as follows.

First, a p-type conductor 10 is prepared, and on the upper surface of the p-type conductor 10, fine particles of LuFe ₂ O ₄ are used to form a CVD (Chemical Vapor Deposition) method, a sputtering method, an MBE (Molecular Beam Epitaxy). The film-like or layer-like current control body 13 is formed by the method or the aerosol deposition method. The upper surface of the p-type conductor 10 may be flattened and the crystal plane may be adjusted as necessary.

Next, the film-like or layer-like current control body 13 is formed into a predetermined shape by electron beam lithography.

Next, a metal layer is formed on the current control body 13 and the p-type conductor 10 by sputtering or the like, a required etching mask is formed on the metal layer, and the metal layer is etched to thereby form a drain electrode. 11, a source electrode 12 and a gate electrode 14 are formed.

The formation of the current control element is not limited to the above method, and an appropriate method may be used.

[Second Embodiment]
As shown in FIG. 5, the current control element according to the second embodiment corresponds to a dielectric insulating film 20 serving as a support base, a current control body 21 provided on the upper surface of the dielectric insulating film 20, and a current control body 21, respectively. A drain electrode 22 and a source electrode 23 provided on the upper surface of the dielectric insulating film 20 in contact with each other and a gate electrode 24 provided on the lower surface of the dielectric insulating film 20 are configured. The gate electrode 24 is provided immediately below the current control body 21 with the dielectric insulating film 20 interposed therebetween.

The current control body 21 is also LuFe ₂ O ₄ in this embodiment. The current control body 21 is not limited to LuFe ₂ O ₄ , and R is changed to In, Sc, Y, Dy, Ho, Er, Tm, Yb, Lu, Ti, Ca, Sr, Ce, Sn, Hf. At least one element selected from the group consisting of Ma, Mb, at least one element selected from Ti, Mn, Fe, Co, Cu, Ga, Zn, Al, Mg, and Cd, n being one or more Or a compound having a layered triangular lattice structure represented by (RMbO3 _-δ ) _n (MaO) _m , where m is an integer of 0 or more and δ is a real number of 0 or more and 0.2 or less, or one of R of the compound A compound in which a part is substituted with an element having a positive divalent value or less can be used. Hereinafter, the current control body 21 will be described as LuFe ₂ O ₄ .

The current control body 21 may be a single crystal of LuFe ₂ O ₄ or may be polycrystalline, but in the case of a single crystal, the current that is in the same direction as the thickness direction of the dielectric insulating film 20 By controlling the thickness direction of the control body 21 to the c-axis direction of LuFe ₂ O ₄ , current control can be performed effectively.

In particular, in the current control element of the present embodiment, by applying a predetermined voltage to the gate electrode 24, a predetermined electric field acts on the current control body 21 to cause modulation of channel conduction, and the current control body 21 Current control between the source and drain electrodes can be performed.

The current control element of the second embodiment is formed as follows.

First, a film-like or layer-like film is formed on the upper surface of a thin plate-like or thin-film dielectric insulating film 20 by using a fine particle-like LuFe ₂ O ₄ by a CVD method, a sputtering method, an MBE method, an aerosol deposition method, or the like. A current control body 21 is formed.

Next, the film-like or layer-like current control body 21 is formed into a predetermined shape by electron beam lithography.

Next, a metal layer is formed on the upper surfaces of the current control body 21 and the dielectric insulating film 20 by sputtering or the like, a required etching mask is formed on the metal layer, and the metal layer is etched, whereby the drain electrode 22 and source electrode 23 are formed.

Further, a metal layer is formed on the lower surface of the dielectric insulating film 20 by a sputtering method or the like, a required etching mask is formed on the metal layer, and the gate electrode 24 is formed by etching the metal layer. .

[Third Embodiment]
As shown in FIG. 6, the current control element according to the third embodiment includes an insulating substrate 30 serving as a support base, a first electrode 31 provided on the upper surface of the insulating substrate 30, and an upper surface of the first electrode 31. The current control body 32 and the second electrode 33, the third electrode 34, and the fourth electrode 35 provided on the upper surface of the current control body 32 so as to be spaced apart from each other.

In particular, the first electrode 31 and the third electrode 34 are disposed to face each other with the current control body 32 interposed therebetween, and the third electrode 34 is disposed between the second electrode 33 and the fourth electrode 35.

For the insulating substrate 30, ScAlMgO ₄ or the like can be suitably used.

The current control body 32 is also LuFe ₂ O ₄ in this embodiment. The current control body 32 is not limited to LuFe ₂ O ₄ , and R is changed to In, Sc, Y, Dy, Ho, Er, Tm, Yb, Lu, Ti, Ca, Sr, Ce, Sn, Hf. At least one element selected from the group consisting of Ma, Mb, at least one element selected from Ti, Mn, Fe, Co, Cu, Ga, Zn, Al, Mg, and Cd, n being one or more Or a compound having a layered triangular lattice structure represented by (RMbO3 _-δ ) _n (MaO) _m , where m is an integer of 0 or more and δ is a real number of 0 or more and 0.2 or less, or one of R of the compound A compound in which a part is substituted with an element having a positive divalent value or less can be used. Hereinafter, the current control body 32 will be described as LuFe ₂ O ₄ .

The current control body 32 may be a single crystal of LuFe ₂ O ₄ or may be polycrystalline, but when it is a single crystal, it is sandwiched between the first electrode 31 and the third electrode 34. The current control can be effectively performed by setting the thickness direction of the current control body 32 to the c-axis direction of LuFe ₂ O ₄ .

That is, in the current control element of the present embodiment, the second electrode 33 and the fourth electrode 35 are used as the source electrode or the drain electrode, respectively, and by applying a predetermined voltage to each of the first electrode 31 and the third electrode 34, A predetermined electric field is applied to the current control body 32 sandwiched between the first electrode 31 and the third electrode 34 to control the current flowing between the second electrode 33 and the fourth electrode 35 via the current control body 32. ing.

That is, since the current control element of the present embodiment is a transistor that does not use a pn junction, a so-called forward voltage drop does not exist in principle, and can function as a transistor that operates at a low driving voltage.

The current control element of the third embodiment is formed as follows.

First, a first electrode 31 is formed by forming a metal layer on the upper surface of the insulating substrate 30 by sputtering or the like.

Next, a film-like or layer-like current control body 32 is formed on the upper surface of the first electrode 31 by using finely divided LuFe ₂ O ₄ by CVD, sputtering, MBE, aerosol deposition, or the like. ing.

Next, a metal layer is formed on the upper surface of the current control body 32 in the form of a film or a layer by sputtering or the like, a required etching mask is formed on the metal layer, and the metal layer is etched to form a first layer. Two electrodes 33, a third electrode 34, and a fourth electrode 35 are formed.

The current control element according to the third embodiment is not limited to the form shown in FIG. 6. For example, as shown in FIG. 7, the first electrode 31, the second electrode 33, the third electrode 34, and the fourth electrode 35 are provided. It can also be arranged.

That is, when the current control element shown in FIG. 7 is formed, first, a metal layer is formed on the upper surface of the insulating substrate 30 by sputtering or the like, and a required etching mask is formed on the metal layer. The first electrode 31 is formed by etching the layer.

Next, a film-like or layered LuFe ₂ O ₄ layer is formed on the upper surface of the first electrode 31 by using finely divided LuFe ₂ O ₄ by CVD, sputtering, MBE, aerosol deposition, or the like. The current control body 32 is formed with the LuFe ₂ O ₄ layer having a predetermined shape by electron beam lithography.

Next, a metal layer is formed on the upper surface of the current control body 32 by sputtering or the like, a required etching mask is formed on the metal layer, and the metal layer is etched. An electrode 34 and a fourth electrode 35 are formed to form a current control element.

In particular, the third electrode 34 is provided at least directly above the first electrode 31. The second electrode 33 and the fourth electrode 35 are provided in contact with the current control body 32, respectively.

Alternatively, in the current control element, as shown in FIG. 8, a first electrode 31, a second electrode 33, a third electrode 34, and a fourth electrode 35 can be arranged.

That is, in the current control element, first, fine particles of LuFe ₂ O ₄ are used on the upper surface of the insulating substrate 30 to form a film-like or layer-like current by CVD, sputtering, MBE, aerosol deposition, or the like. A control body 32 is formed.

Next, a metal layer is formed on the upper surface of the current control body 32 in the form of a film or a layer by sputtering or the like, a required etching mask is formed on the metal layer, and the metal layer is etched, whereby the first An electrode 31, a second electrode 33, a third electrode 34, and a fourth electrode 35 are formed to form a current control element.

In particular, the first electrode 31 and the third electrode 34 are arranged to face each other, and the second electrode 33 and the fourth electrode 35 are also arranged to face each other, and the first electrode 31 and the third electrode 34 are arranged. And a virtual line connecting the second electrode 33 and the fourth electrode 35 are arranged so as to cross each other.

Furthermore, the current control body 32 sets the c-axis direction of LuFe ₂ O ₄ as the extending direction of the imaginary line connecting the first electrode 31 and the third electrode 34.

Therefore, even in the current control element shown in FIG. 8, by applying predetermined voltages to the first electrode 31 and the third electrode 34, the current control body 32 positioned between the first electrode 31 and the third electrode 34 is applied. It is possible to control the current flowing between the second electrode 33 and the fourth electrode 35 via the current control body 32 by applying a predetermined electric field.

According to the present invention, it is possible to provide a current control element that operates with a small driving power, and to achieve power saving of an electronic circuit.

Claims (6)

A current control body that controls the amount of current by applying an electric field;
A current control element having an electrode for applying a predetermined electric field to the current control body,
A current control element comprising the current control body made of a compound having a layered triangular lattice structure containing a rare earth element. The current controller is
R is at least one element selected from In, Sc, Y, Dy, Ho, Er, Tm, Yb, Lu, Ti, Ca, Sr, Ce, Sn, and Hf,
Ma and Mb, at least one element selected from Ti, Mn, Fe, Co, Cu, Ga, Zn, Al, Mg, and Cd with duplication allowed,
n is an integer of 1 or more,
m is an integer greater than or equal to 0,
A compound having a layered triangular lattice structure represented by (RMbO _{3 -δ} ) _n (MaO) _m or a part of R of the compound was substituted with an element less than positive divalent, where δ is a real number between 0 and 0.2. The current control element according to claim 1, which is a compound. The current control element according to claim 1 or 2, wherein the current control body is joined between the drain electrode and the source electrode of a p-type conductor provided with a drain electrode and a source electrode. The current control element according to claim 1, wherein the current control body is provided with an input side electrode for inputting a current and an output side electrode for outputting a current. 5. The current control element according to claim 1, wherein a direction of an electric field applied to the current control body is a c-axis direction of the compound portion. A method for manufacturing a current control element, comprising: a current control body that controls the amount of current by applying an electric field; and an electrode that applies a predetermined electric field to the current control body,
A current control element comprising a step of forming the current control body with a compound having a layered triangular lattice structure containing a rare earth element.

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