JP2021100033A - Detection element and light emitting element for infrared light - Google Patents

Abstract

To provide a compact detection element and a light emitting element for infrared light having a high signal-to-noise ratio and high photoelectric conversion efficiency.SOLUTION: A detection or light emitting element for infrared light includes a light-sensitive unit consisting of a plurality of light-sensitive pieces having layer structure in which a dielectric layer and a second conductor layer are sequentially laminated on a surface composed of a first conductor layer having a planar shape of a main size L arranged two-dimensionally with a period P, a wire unit made of a wire piece having a maximum width of more than 0 and L/5 or less for connecting at least the second conductor layers of the adjacent light-sensitive pieces with a non-linear unit, and the thickness of the dielectric layer exceeds 0 and is less than λ/2n when the refractive index of the dielectric layer is n, and the area of the light-sensitive piece is (3λ/8n)2 or more (5λ/8n)2 or less, the element has an in-plane propagation mode in which the light-sensitive piece and the wire piece propagate in the arrangement direction and are polarized in the direction perpendicular to the plane, and the planar shape of a functional unit consisting of the light-sensitive unit and the wire unit has a symmetry of 3 times or more.SELECTED DRAWING: Figure 1

Description

The present invention relates to an infrared light detection element and a light emitting element.

Infrared detection elements and light emitting elements are widely used in infrared image sensors and surveillance sensors. For example, infrared rays in a long wavelength band of 2 μm or more are strong against motion sensors that detect the human body, heat source movement monitoring sensors, non-contact temperature sensors, gas sensors, etc. due to their thermal effect and infrared absorption effect by gas. There is demand.
In view of environmental improvement, gas sensors that can be used for monitoring and protecting the atmospheric environment and for early detection of fires are essential devices. In particular, since there are many absorption bands peculiar to various gases in the region from the wavelength of 3 μm to the wavelength of 10 μm, there is a strong demand for a gas sensor capable of detecting this region with a high S / N ratio and high sensitivity. There is also a strong demand for light emitting devices for infrared light.

A patch antenna is known as a structure for efficiently transmitting and receiving radio waves (see Patent Documents 1 and 2). Recently, it has been further evolved and developed as a structure that efficiently absorbs radio waves such as microwaves and infrared light. Metal-insulator-metal (MIM) that utilizes half-wave resonance in transverse magnetic (TM) gap plasmon mode. ) A patch antenna composed of a cavity has been developed (see Non-Patent Document 1).
The MIM cavity can strongly absorb light and electromagnetic waves even though it is a thin structure by utilizing a strong interaction with a tightly confined electric field. On top of that, metal layers formed above and below the insulator, which is a functional material, can be used as electrodes. For this reason, a patch antenna element exhibiting high detection sensitivity to infrared rays has been developed by connecting the patch antennas with a simple one-dimensional straight wire (see Non-Patent Document 2).

However, a detection element for infrared light, which has higher infrared light detection sensitivity, can secure a higher S / N ratio, and can be miniaturized (compactified), has been desired.
Further, like the detection element for infrared light, a light emitting element for infrared light having strong emission intensity of infrared light, high directivity, and miniaturization (compactification) has been desired. ..

Japanese Unexamined Patent Publication No. 52-134350 Japanese Unexamined Patent Publication No. 05-20627

Phys. Rev. Lett. , Vol. 96, p. 097401 (2006) Apple. Phys. Lett. , Vol. 104, p. 031113 (2014)

An object of the present invention is to provide a compact detection element and light emitting element for infrared light having a high S / N ratio and a high photoelectric conversion efficiency. That is, the detection element provides a compact infrared light detection element having a low noise level and high detection sensitivity, and the light emitting element is in a state where the wavelength and the radiation direction are highly controlled. It is an object of the present invention to provide a compact light emitting element for infrared light having a strong light emitting intensity.

The configuration of the present invention is shown below.
(Structure 1)
An element that detects or emits infrared light with a peak wavelength of λ.
The element has at least a light-sensitive portion that is sensitive to the infrared light and a wire portion that makes an electrical connection.
The light-sensitive portion is composed of a plurality of light-sensitive pieces having a planar shape of main size L arranged two-dimensionally with a period P.
The light-sensitive piece has a layer structure in which a dielectric layer and a second conductor layer are sequentially laminated on a surface made of a first conductor layer.
The thickness T of the dielectric layer is more than 0 and less than λ / (2n) when the refractive index of the dielectric layer with respect to λ is n.
Area of the light-sensitive strip is ² or less {3λ / ^{(8n)} 2} or {5λ / ^(8n)},
The wire portion connects at least the second conductor layers of the adjacent light-sensitive pieces with a non-linear portion, and has a maximum width of more than 0 and L / 5 or less. Consists of
The element has an in-plane propagation mode in which the photosensitizer and the wire piece propagate in the first direction, which is the direction of the arrangement, and are polarized in the second direction, which is the direction perpendicular to the plane. And
With respect to the infrared light incident from the second direction.
_{| k a × L + k w} × (P-L) -2 × m × π | ≦ π / 2 (m is a positive integer)
There relationship, a positive propagation constant portion and portions of the wire piece of the light-sensitive strip of the propagation modes traveling in the first direction when a k _a, k _w respectively,
An element in which the planar shape of the functional portion including the light-sensitive portion and the wire portion has symmetry of three times or more.
(Structure 2)
The element according to configuration 1, wherein the dielectric layer includes a semiconductor layer.
(Structure 3)
The semiconductor layer is composed of Si, Ge, AlAs, GaAs, InAs, AlSb, GaSb, InSb, AlP, GaP, InP, AlN, GaN, InN, PbS, PbSe, ZnTe, CdTe, HgTe, ZnSe, CdSe, MgSe. The infrared light detection element and light emitting element according to the configuration 2, which comprises one or more selected from the group.
(Structure 4)
The element according to configuration 2, wherein the semiconductor layer includes a quantum well.
(Structure 5)
The element according to configuration 4, wherein the number of quantum wells is 1 or more and 5 or less.
(Structure 6)
The element according to configuration 4, wherein the number of the quantum wells is 1.
(Structure 7)
The quantum wells are GaAs and AlGaAs, InGaAs and InAlAs, InGaAs and InP, InGaAs and AlAsSb, InGaAsP and InP, GaAs and GaInP, GaAs and AlInP, GaN and AlGaN, GaN and AlN, InAs and AlAsSb, ZnCdSe and ZnCdMgSe, InAs. The element according to any one of configurations 4 to 6, which comprises 1 or more selected from the group consisting of GaSb, InAs and GaInSb, InAs and InAsSb, InGaAs and GaAsSb, and InAs and AlGaSb.
(Structure 8)
The element according to any one of configurations 1 to 7, wherein the first conductor layer and the dielectric layer, and the dielectric layer and the second conductor layer are both in ohmic contact.
(Structure 9)
The element according to configuration 1, wherein the dielectric layer is made of an insulator.
(Structure 10)
The dielectric layer is diamond, Si, Ge, MgO, Al ₂ O ₃ , SiO ₂ , BeO, CaO, TiO ₂ , Ti ₂ O ₃ , TiO, V ₂ O ₅ , Cr ₂ O ₃ , MnO, Cu _2. O, CuO, ZnO, Sc ₂ O ₃ , Y ₂ O ₃ , ZrO ₂ , Ga ₂ O ₃ , Nb ₂ O ₅ , SnO ₂ , CeO ₂ , HfO ₂ , Ta ₂ O ₅ , LiF, NaF, MgF ₂ , _{AlF 3, CaF 2, SrF 2} , YF 3, CsF, BaF 2, LaF 3, CeF 3, NdF 3, GdF 3, YbF 3, PbF 2, ThF 4, ZnS, ZnSe, ZnTe, CdSe, CdTe, AgGaS 2 , AgGaSe ₂ , Zn ₃ P ₂ , ZnGeP ₂ , As ₂ S ₃ , As ₂ Se ₃ , AlAs, AlSb, GaP, GaAs, GaSb, GaSe, GaTe, InP, SiC, BN, AlN, GaN, NaCl, KCl, One or more selected from the group consisting of AgCl, CsCl, KBr, RbBr, AgBr, CsBr, KI, RbI, AgI, CsI, TlI, TlBr, CaCo ₃ , _{SrTIO 3} , LiTaO ₃ , ZrSiO ₄ , and KNbO _3. 1. The element according to 1.
(Structure 11)
The first conductor layer and the second conductor layer are Ti, Cr, Ni, Au, Pt, Ag, Pd, W, Cu, Yb, Sm, Y, Tb, Ho, Tm, Gd, Er. , Nd, Sc, Zr, Hf, Ta, Nb, V, Fe, Mo, Ru, Co, Rh, Re, Ir, In, Al, one or more metals selected from the group consisting of Ti, Cr, Ni, Au. , Pt, Ag, Pd, W, Cu, Yb, Sm, Y, Tb, Ho, Tm, Gd, Er, Nd, Sc, Zr, Hf, Ta, Nb, V, Fe, Mo, Ru, Co, Rh , Re, Ir, In, Al alloys containing one or more metals selected from the group consisting of, Ti, Cr, Ni, Au, Pt, Ag, Pd, W, Cu, Yb, Sm, Y, Tb, Ho, A compound containing one or more metals selected from the group consisting of Tm, Gd, Er, Nd, Sc, Zr, Hf, Ta, Nb, V, Fe, Mo, Ru, Co, Rh, Re, Ir, In and Al. , And the element according to any one of configurations 1 to 10, comprising any of ITO, AZO, GZO, IZO, IGZO, ATO, FTO, FZO, and TiN.
(Structure 12)
The element according to any one of configurations 1 to 11, wherein the plane shape of the light-sensitive piece is 1 selected from the group consisting of an equilateral triangle, a square, a regular hexagon, a regular octagon, and a perfect circle.
(Structure 13)
The planar shape of the light-sensitive piece is a square whose size is L.
Wherein L, when the lowest order of the effective refractive index of in-plane propagation modes polarized in the second direction of the light-sensitive element was _{n eff, 3λ / (8n eff} ) or 5λ / _{(8n eff)} below And
The effective refractive index n _eff ^{is n · (1 + 2δ / T) 1/2} when the average skin depth of the first conductor layer and the second conductor layer is δ. 11. The element according to any one of 11.
(Structure 14)
The element according to any one of configurations 1 to 13, wherein the planar shape of the wire piece includes a right-angled portion.
(Structure 15)
The element according to any one of configurations 1 to 14, wherein the symmetry is four-fold symmetry.
(Structure 16)
The element according to any one of configurations 1 to 15, wherein the arrangement is in the form of a matrix.
(Structure 17)
The element according to any one of configurations 1 to 16, wherein at least a plurality of second conductor layers of the light-sensitive pieces are formed above the first conductor layer.
(Structure 18)
The element according to any one of configurations 1 to 17, wherein at least a plurality of second conductor layers of the light-sensitive pieces are formed on the dielectric layer.
(Structure 19)
On the outside of the infrared light detection element and the light emitting element according to any one of claims 1 to 18.
A second light-sensitive piece in which the dielectric layer and the second conductor layer are sequentially laminated on a surface made of the first conductor layer.
A second wire having a maximum width of more than 0 and L / 5 or less, which connects at least the second conductor layers of the adjacent second light-sensitive pieces with a non-linear portion. The pieces are arranged in two dimensions,
The wire length of the second wire piece changes according to any distance of one-dimensional, two-dimensional, and polar coordinate radii with the center of gravity of the arrangement of the light-sensitive pieces as the origin. The element according to any one of 1 to 16.
(Structure 20)
The element according to configuration 19, wherein the second wire piece is arranged in the period P.
(Structure 21)
The element according to configuration 19 or 20, wherein the change in wire length is monotonous.

INDUSTRIAL APPLICABILITY The present invention provides a compact detection element and light emitting element for infrared light having a high signal-to-noise ratio and high photoelectric conversion efficiency. That is, in the detection element, a compact infrared light detection element having a low noise level and high detection sensitivity is provided, and in the light emitting element, a compact infrared having a strong light emission intensity with little noise emission. A light emitting device for light is provided.

It is a bird's-eye view which shows the outline structure of an element. It is a top view which shows the outline structure of the element. It is a top view which shows the outline structure of the element. It is a top view which shows the outline structure of the element. It is a top view which shows the outline structure of the element. It is a top view which shows the outline structure of the element. It is a top view which shows the outline structure of the element. It is a top view which shows the outline structure of the element. It is explanatory drawing which shows the band composition of the dielectric which has a quantum well used in this invention. It is a top view which shows the outline structure of the element. It is explanatory drawing of the light absorption characteristic which shows the structure of an element and the light absorption spectroscopic characteristic in comparison. It is an SEM photograph of the element produced in the Example. It is an SEM photograph of the element produced in the Example. It is a characteristic figure which shows the light sensitivity characteristic of the element manufactured in an Example. It is a characteristic figure which shows the light sensitivity characteristic of the element manufactured in an Example. It is a characteristic figure which shows the light sensitivity characteristic of the element manufactured in an Example. It is a characteristic figure which shows the light sensitivity characteristic of the element manufactured in an Example. It is a bird's-eye view which shows the structure of the element of an Example. It is a characteristic figure which shows the light sensitivity characteristic of the element of an Example.

Hereinafter, the present invention will be described in detail. The detailed description of the present invention described below may be based on representative embodiments, embodiments, and examples, but these are examples, and the present invention describes such embodiments, embodiments, and the like. And is not limited to the examples.
In addition, "A to B" indicates A or more and B or less.

(Embodiment 1)
<Element structure>
As shown in FIG. 1, the element 101 of the present invention is a patch antenna having a thin dielectric layer 22 sandwiched between two conductor layers, a first conductor layer 21 and a second conductor layer 23. The light-sensitive pieces 12 act as a light-sensitive piece 12 are regularly arranged in large numbers like a so-called array antenna, and a wire part 13 having a conductor layer for electrically connecting the light-sensitive pieces.
The wire portion 13 is composed of a plurality of wire pieces 14, and each wire piece 14 is a wire that electrically connects at least the second conductor layers 23 of the adjacent light-sensitive pieces 12.

In the configuration of the present invention, since the light-sensitive pieces are connected by the conductor layer, a bias voltage can be applied to the dielectric layer, or a current due to photoelectric conversion can be taken out. Further, a tunnel current can be passed through the dielectric layer 22 by applying a voltage between the two conductor layers, or a current can be passed through the conductor to apply heat to the dielectric layer 22 to cause light emission.

In general, the light detection sensitivity of a photodetector and the light emission intensity of a light emitting element have common behaviors from the viewpoint of photoresonance due to the principle of light retrograde. That is, the condition that the light detection element can cause effective resonance can also cause the light emitting element to cause effective resonance. Hereinafter, the photodetector element will be mainly described, and the matters peculiar to the light emitting element will be described individually as appropriate.

The element 101 of the present invention is characterized in the shape, size, structure, and arrangement of the light sensitive piece 12 and the wire piece. Further, the dielectric layer 22 is also characterized in order to further improve the performance.

The light-sensitive piece 12 has a cavity structure composed of three layers, a first conductor layer 21, a dielectric layer 22, and a second conductor layer 23, and the thickness T of the dielectric layer 22 exceeds 0. λ / (2n) or less, the area of the photosensitive member 12 is ² or less {3λ / ^{(8n)} 2} or {5λ / ^(8n)}.
It has been found that by adopting this structure, half-wave resonance in TM gap plasmon mode efficiently occurs in a state where noise is suppressed, and infrared light is efficiently absorbed. Further, in this structure, since the dielectric layer 22 is thin, the electric field generated by resonance is large, a large sensitivity enhancement can be obtained, and the volume is small, so that the dark current is reduced as a result. Since the dark current can be suppressed, the device can be sufficiently used even in a low temperature environment such as a liquid nitrogen environment.

When the light-sensitive piece 12 is a square having a size of L, n · (1 + 2δ / T) ^{1 when the average skin depth of the first conductor layer and the second conductor layer is δ.} When the effective refractive index of the lowest-order in-plane propagation mode polarized in the second direction of the light-sensitive piece 12 represented by ^{/ 2} _{is n eff} , L is _{3λ / (8n eff} ) or more and 5λ / (8n). _eff ) It is preferable that the value is less than or equal to.
It was found that this structure is optimized for a square light-sensitive piece, and that half-wave resonance in TM gap plasmon mode efficiently occurs and infrared light is efficiently absorbed while suppressing noise. ..
Here, λ is the peak wavelength of infrared light to be detected or emitted by this device, and n is the refractive index of the dielectric layer 22 with respect to the wavelength λ. The infrared light in the present invention refers to light having a wavelength of 0.76 μm or more and 1000 μm or less. Further, the wavelength range of infrared light that is particularly effective in the present invention is 2.5 μm or more and 25 μm or less.

In the present invention, the light-sensitive pieces 12 having a planar shape of the main size L are arranged two-dimensionally with a period P, and the adjacent light-sensitive pieces 12 and the wire pieces 14 are arranged two-dimensionally with a period P. By electrically connecting the light-sensitive pieces 12, the group of the light-sensitive pieces 12 is brought into a resonance state to further absorb infrared light with high efficiency. Here, the two-dimensional array is typically a matrix array, and includes a square lattice pattern, a rectangular lattice pattern, an orthorhombic lattice pattern, and a triangular lattice pattern. Of these, the square grid is the easiest to design and can be used preferentially.
The planar shape of the light-sensitive piece 12 is preferably one having high symmetry, and specific examples thereof include an equilateral triangle, a square, a regular hexagon, a regular octagon, and a perfect circle. Of these, squares are particularly preferred because they are easy to manufacture. When the plane shape of the light sensitive piece 12 has high symmetry, the direction of the incident light and the dependence on polarization are reduced, and it is preferable because the sensitivity is stable at a high level in a state of being less susceptible to these disturbances.

Here, in order to increase the degree of integration of the light-sensitive pieces 12 by narrowing the distance between the adjacent light-sensitive pieces 12 and to make the element 101 compact, the maximum width of the wire piece 14 exceeds 0 and is L / 5 or less. Therefore, it is assumed that the conductor layer has a folded shape having a bent portion such as a Z or S shape having a non-linear portion. An example thereof is shown in FIG. FIG. 2 is a plan view of a part of the element 101 as viewed from above. FIG. 2A is a plan view in which only a light sensitive piece is arranged, and FIG. 2B is a light sensitive piece 12 and a linear wire piece 14a. Is arranged, (c) is the case where the light sensitive piece 12 and the Z-shaped wire piece 14b are arranged, and (d) is the case where the light sensitive piece 12 and the S-shaped wire piece 14c are arranged. If you are. Here, in order to narrow the region and form an efficient folding plane shape, it is preferable to include a right-angled shape portion.
Here, the main size L is the length of one side if the light-sensitive piece 12 is square, the length of one side if it is an equilateral triangle, and the diagonal line if it is a regular n-sided polygon (n is an even number of 6 or more) such as a regular hexagon and a regular octagon. The length of a circle, the diameter in the case of a circle, and the diameter of a circle with the same area in other cases.

As a result of detailed examination, it was found that in order to match the resonance state of the group of light sensitive pieces 12 with the wavelength λ, it is necessary to satisfy the following conditions in consideration of the shape of the bent portion and the photonic band gap. It was.
The element 101 propagates the light-sensitive piece 12 and the wire piece 14 in the first direction, which is the arrangement direction thereof, and the electric field is generated in the second direction, which is the direction perpendicular to the surface on which the light-sensitive piece 12 is placed. It has a polarized in-plane propagation mode, and with respect to the infrared light incident from the second direction.
_{| k a × L + k w} × (P-L) -2 × m × π | ≦ π / 2 (m is an appropriate positive integer) .. (1)
Relationship is a positive propagation constant of the light portion of the photosensitive member 12 and the portion of the wire piece 14 of the propagation modes traveling in the first direction when a k _a, k _w respectively.

In the element 101, the resonance (2) is a combination of two optical resonances of the individual optical resonance of the photosensitive piece 12 and the optical resonance of the whole through the wire piece 14 with respect to the incident light (detection light). (Multiple resonance). In this case, the resonance caused by the vertically incident light on the element 101 is a very strong resonance, but the resonance characteristic is that the light incident on the element 101 at an angle suddenly deviates from the resonance condition.
In an infrared photodetector, most of the background noise is caused by thermal radiation from the surroundings. In the element 101, in order to suppress heat radiation from the surroundings easily, at low cost, and compactly, and to make the element with less noise, the directivity is enhanced by using the above-mentioned double resonance, in other words, FOV (Field Of View). Was narrowed to reduce the sensitivity to heat radiation (infrared rays) from the surroundings. As a result, in the infrared photodetector element in which heat radiation from the surroundings becomes a problem, the element 101 becomes an element excellent in S / N while obtaining high detection sensitivity. In particular, in the case of an infrared light detection element that utilizes an intersubband transition of a quantum well, the quantum well itself has resonance sensitivity (electronic resonance) at a specific wavelength. By matching this with double optical resonance and triple resonance, it becomes an element with a high S / N that is particularly strong and is not affected by unnecessary thermal radiation in terms of wavelength and direction. Alternatively, in an infrared light emitting device in which unnecessary heat radiation given to the surroundings is a problem, the device is excellent in directivity while obtaining high light emitting intensity.

Further, the element 101 makes the planar shape of the functional portion including the light-sensitive portion 11 and the wire portion 13 three-fold symmetric or more, preferably four-fold symmetric. That is, the light-sensitive piece 12 and the wire piece 14 are arranged at a period P so as to be symmetrical at least 3 times, preferably 4 times. As a result, the polarization dependence of the incident light (polarization angle dependence) is almost eliminated, which contributes to the improvement of sensitivity.

The shapes of the light-sensitive portion and the wire portion formed on the first conductor layer 21, the dielectric layer 22, and the second conductor layer 23 are not limited to those shown in the bird's-eye view of FIG. The wire portion 13 may or may not sandwich the dielectric layer 22, and the first conductor layer 21 and the dielectric layer 22 may have a patterned shape and may be a flat plate in a wide area on which a plurality of light-sensitive pieces and wire pieces are placed. It may be in the form.

FIG. 3 shows a plan view when FIG. 1 is divided into the first conductor layer 21, the dielectric layer 22, and the second conductor layer 23. The second conductor layer 23 is shown in FIG. 3 (a), and the dielectric layer 22 and is shown in FIG. 3 (b). The first conductor layer 21 is shown in FIG. 3 (c). In the case of FIG. 3, the planar shape of the second conductor layer 23 is a shape having a light-sensitive portion 11 and a wire portion 13, and the planar shape of the dielectric layer 22 is the same as that of the light-sensitive portion 11. The planar shape of 21 is a wide planar shape on which a plurality of light-sensitive pieces and wire pieces are placed.
FIG. 4 shows the planar shape of each layer when the dielectric layer 22 has only the light-sensitive portion 11 and does not include the wire portion, and FIG. 5 shows the first conductor layer 21, the dielectric layer 22, and the second conductor layer 23. 6 has the same planar shape including the light-sensitive portion 11 and the wire portion 13, and FIG. 6 shows that the first conductor layer 21 and the second conductor layer 23 have the same planar shape including the light-sensitive portion 11 and the wire portion 13 and are a dielectric material. The layer 22 has a planar shape having only the light-sensitive portion 11 and no wire portion, and FIG. 7 has a planar shape having only the light-sensitive portion 11 and the wire portion 13 only for the second conductor layer 23, and the first conductor layer 21 has a planar shape. The dielectric layer 22 has a wide planar shape on which a plurality of light-sensitive pieces and wire pieces are placed, and FIG. 8 shows that the first conductor layer 21 and the second conductor layer 23 include the light-sensitive portion 11 and the wire portion 13. In the case of a planar shape, the dielectric layer 22 has a wide planar shape in which a plurality of light-sensitive pieces and wire pieces are placed only on the light-sensitive portion. The element 101 of the present invention may have any of the above-mentioned planar shapes.

When a wide planar shape on which a plurality of light-sensitive pieces and wire pieces are placed is used, there is a feature that the formation of the layer does not involve the formation of a fine pattern, so that the production is easy. Further, in the cases shown in FIGS. 5 and 6, since the wire pieces act as springs to connect the light-sensitive pieces, the flexibility and stretch durability are increased when the wire pieces are formed on the flexible substrate, which is preferable.

The dielectric layer 22 is composed of a semiconductor layer and / and a layer including an insulator layer.
The semiconductor layer is a group consisting of Si, Ge, AlAs, GaAs, InAs, AlSb, GaSb, InSb, AlP, GaP, InP, AlN, GaN, InN, PbS, PbSe, ZnTe, CdTe, HgTe, ZnSe, CdSe, MgSe. One or more selected from the above can be mentioned, and it is particularly suitable for obtaining high detection sensitivity and high S / N when the element 101 is used as an optical detection element.

When the semiconductor layer includes a quantum well, it is suitable for detecting infrared light in a predetermined narrow wavelength range determined by the design of the quantum well structure with extremely high sensitivity and S / N. That is, when a semiconductor layer including a quantum well is used, it becomes a detection element in a narrow wavelength region with high sensitivity, while thermal radiation, which is a noise source, generally has a wide wavelength region, so that a high S / N can be obtained.
Here, the quantum wells include GaAs and AlGaAs, InGaAs and InAlAs, InGaAs and InP, InGaAs and AlAsSb, InGaAsP and InP, GaAs and GaInP, GaAs and AlGaN, GaN and AlGaN, GaN and AlN, InAs and AlAsSb, and ZnCdSe. One or more selected from the group consisting of ZnCdMgSe, InAs and GaSb, InAs and GaInSb, InAs and InAsSb, InGaAs and GaAsSb, and InAs and AlGaSb can be mentioned.

If the quantum wells are defective, the photodetection sensitivity and S / N will decrease, so it is preferable that the number of quantum wells is small. Further, in general, the light absorption by a quantum well in the absence of absorption enhancement by the cavity is approximately proportional to the number of quantum wells, but the element of the present invention has a cavity structure using half-wavelength resonance in TM gap plasmon mode. Therefore, even if the number of quantum wells is small, the absorption is sufficiently large. In addition to absorption, the photoconductive gain (the ease with which electrons move through a group of quantum wells), which is another factor that determines sensitivity, is approximately inversely proportional to the number of quantum wells. The smaller the number, the more responsive it is. As a result of detailed examination, it was found that the number of quantum wells is preferably 1 or more and 5 or less, more preferably 1 or more and 3 or less, and even more preferably 1.

Further, it is preferable that the first conductor layer 21 and the dielectric layer 22 and the dielectric layer 22 and the second conductor layer 23 are in ohmic contact with each other. Ohmic contact smoothes the flow of electrons at the interface between the first conductor layer 21 and the dielectric layer 22 and the interface between the dielectric layer 22 and the second conductor layer 23, and efficiently distributes photocurrent. It can be taken out. If it is a Schottky contact instead of an ohmic contact, the electrons accumulated in the dielectric layer 22 will stay, and it will not be easy to take out a sufficient photocurrent.

FIG. 9 shows an explanatory diagram of the conduction band structure when a semiconductor layer having one quantum well is used for the dielectric layer 22. This explains the conduction band structure of the dielectric layer used in the device of the first embodiment.
The vertical axis of FIG. 9 represents the energy of electrons, and the shaded area represents that the electrons are full. Since the quantum well is thin, the electron levels exist discretely.
In addition to the ground level, the electrons in the quantum well can exist in continuously excited levels that are continuously distributed with a predetermined energy width. In that state, when an infrared photon having an energy equal to the energy difference between the two levels is incident, the electron at the base level is excited to the excitation level. When a bias voltage is applied between the first conductor layer and the second conductor layer, the excited electrons move in the direction corresponding to the bias voltage by the electric field, and pass through the contact layer to the conductor layer. It reaches and the photocurrent flows.
FIG. 9 shows a case where a Schottky barrier exists at the boundary between the contact layer and the conductor layer, and as described above, ohmic contact is preferable. However, even with a Schottky barrier, if the contact layer is doped with sufficient electrons, the barrier becomes extremely thin as shown in FIG. 9, and the electrons tunnel and freely flow between the contact layer and the conductor layer. It will be possible to use it because it will be possible.

When the light emitting element is used, a structure in which the dielectric layer 22 includes an insulator layer can be preferably used. Emission can be achieved by two methods, thermal excitation and tunneling current.
In the method using thermal excitation, an electric current is passed through one or both of the first conductor layer 21 and the second conductor layer 23, and Joule heat is applied to the dielectric layer 22 to cause light emission. As another method of applying heat, light absorption can be mentioned. In this case, the thickness of the insulator layer is preferably 1 nm or more and 500 nm or less, and more preferably 10 nm or more and 300 nm or less.
In the method using the tunnel current, a bias voltage is applied between the first conductor layer 21 and the second conductor layer 23 to allow the tunnel current to flow through the insulator layer to cause light emission. In this case, the insulator layer needs to be set to a thickness that allows the tunnel current to flow. Specifically, the thickness of the insulator layer is preferably 1 atomic layer or more and 10 nm or less, and more preferably 3 atomic layers or more and 3 nm or less.

Examples of the insulator layer include diamond, Si, Ge, MgO, Al ₂ O ₃ , SiO ₂ , BeO, CaO, TiO ₂ , Ti ₂ O ₃ , TiO, V ₂ O ₅ , Cr ₂ O ₃ , MnO, and the like. Cu ₂ O, CuO, ZnO, Sc ₂ O ₃ , Y ₂ O ₃ , ZrO ₂ , Ga ₂ O ₃ , Nb ₂ O ₅ , SnO ₂ , CeO ₂ , HfO ₂ , Ta ₂ O ₅ , LiF, NaF, MgF ₂ , AlF ₃ , CaF ₂ , SrF ₂ , YF ₃ , CsF, BaF ₂ , LaF ₃ , CeF ₃ , NdF ₃ , GdF ₃ , YbF ₃ , PbF ₂ , ThF ₄ , ZnS, ZnSe, ZnTe, AgGaS ₂ , AgGaSe ₂ , Zn ₃ P ₂ , ZnGeP ₂ , As ₂ S ₃ , As ₂ Se ₃ , AlAs, AlSb, GaP, GaAs, GaSb, GaSe, GaTe, InP, SiC, BN, AlN, GaN, Na Selected from the group consisting of KCl, AgCl, CsCl, KBr, RbBr, AgBr, CsBr, KI, RbI, AgI, CsI, TlI, TlBr, CaCo ₃ , _{SrTIO 3} , LiTaO ₃ , ZrSiO ₄ , KNbO _{3 or more.} be able to.

The first conductor layer 21 and the second conductor layer 23 are not particularly limited as long as they are conductive materials, but for example, Ti, Cr, Ni, Au, Pt, Ag, Pd, W, Cu, Group consisting of Yb, Sm, Y, Tb, Ho, Tm, Gd, Er, Nd, Sc, Zr, Hf, Ta, Nb, V, Fe, Mo, Ru, Co, Rh, Re, Ir, In, Al One or more metals selected from, Ti, Cr, Ni, Au, Pt, Ag, Pd, W, Cu, Yb, Sm, Y, Tb, Ho, Tm, Gd, Er, Nd, Sc, Zr, Hf, Alloys containing one or more metals selected from the group consisting of Ta, Nb, V, Fe, Mo, Ru, Co, Rh, Re, Ir, In, Al, Ti, Cr, Ni, Au, Pt, Ag, Pd. , W, Cu, Yb, Sm, Y, Tb, Ho, Tm, Gd, Er, Nd, Sc, Zr, Hf, Ta, Nb, V, Fe, Mo, Ru, Co, Rh, Re, Ir, In , A compound containing one or more metals selected from the group consisting of Al, and any of ITO, AZO, GZO, IZO, IGZO, ATO, FTO, FZO, and TiN.

From the above, the element 101 of the first embodiment provides a compact detection element and a light emitting element for infrared light having a high S / N ratio and a high photoelectric conversion efficiency.

<Device manufacturing method>
The element 101 of the first embodiment can be manufactured by the following steps.

The first method is particularly suitable when the dielectric layer is used as an insulating film.
A substrate is prepared and a first conductor layer is formed on the substrate. Here, the first conductor layer may also serve as the substrate. The substrates include GaAs substrates, Si substrates, InP substrates, sapphire substrates, synthetic quartz glass, borosilicate glass, glass substrates such as soda lime glass, ceramic substrates such as alumina and silicon nitride, acrylic, polystyrene (PS), and polypropylene ( Organic material substrates such as PP), polyethylene terephthalate (PET), and polycarbonate (PC), and metal substrates such as aluminum, iron, stainless steel, and copper can be preferably used. When the substrate is not insulating, it is also preferable to form an oxide film, a nitride film and / or an oxynitride film on the surface of the substrate. Here, the substrate may be one having sufficient rigidity such as Si or synthetic quartz, or one having sufficient flexibility such as PET.
Next, the first conductor layer is formed on the substrate. Examples of the method for forming the first conductor layer include a sputtering method, a heat vapor deposition method, an electron beam deposition method, a CVD (Chemical Vapor Deposition) method, a MOCVD (Metalorganic Vapor Deposition) method, and an atomic layer deposition method.
After that, the dielectric layer is formed on the first conductor layer. Examples of the method for forming the dielectric layer include a sputtering method, a heat vapor deposition method, an electron beam deposition method, a CVD method, a MOCVD method, a sol-gel method, a spin coating method, a dip coating method, a bonding method, and an atomic layer deposition method. be able to.
After that, a second conductor layer is formed on the dielectric layer. Examples of the method for forming the second conductor layer include a sputtering method, a heat vapor deposition method, an electron beam deposition method, a CVD method, a MOCVD method, and an atomic layer deposition method.

Next, lithography and etching are performed to form a pattern of a light-sensitive portion having a plurality of light-sensitive pieces and a pattern of a wire portion having a plurality of wire pieces on the second conductor layer. Then, the dielectric layer is also etched by using those patterns as a mask.
Here, as the lithography, electron beam lithography, EUV lithography, and nanoimplanting, which are excellent in microfabrication, are preferable, but KrF lithography, ArF lithography, and ArF immersion lithography may also be used. As the etching, dry etching such as reactive ion etching having excellent microfabrication can be preferably used.
Further, in forming the pattern of the second conductor layer, it may be formed by a lift-off method without using etching. That is, a lift-off resist pattern is formed on the dielectric layer by lithography, a second conductor layer is deposited by a sputtering method or a vapor deposition method, and then the resist is removed to have a pattern of a light-sensitive portion and a wire portion. 2 conductor layers may be formed. Since the pattern formation of the dielectric layer is performed by self-alignment with the pattern of the second conductor layer as a mask, problems such as misalignment do not occur. Since the wire piece is thin, this self-alignment formation makes it possible to form a high yield.
Through the above steps, the element 101 having the structure shown in FIG. 1 is manufactured.

The second method is a method of forming the dielectric layer first, which is a suitable manufacturing method when the dielectric layer has a semiconductor layer having a crystal structure. In the second method, a high-quality semiconductor layer is easily formed, so that the performance of the element 101 can be easily improved.

First, a first substrate having sufficient rigidity is prepared, and a buffer layer and a sacrificial layer responsible for surface flattening are sequentially formed on the first substrate.

The first substrate can be used as long as it has sufficient rigidity and a semiconductor layer can be epitaxially formed on the substrate.
The material of the buffer layer is not particularly limited as long as the surface thereof can be sufficiently flattened and smoothed.
Examples of the method for producing the buffer layer include MBE (Molecular Beam Epitaxy), MOCVD, MOPVE (MetalOrganic Vapor Phase Epitaxy), HVPE (Hydride Vapor Phase Epitaxy), HVPE (Hydride Vapor Phase Epitaxy, etc.) It is not limited to.
The thickness of the buffer layer is not particularly limited, but may be, for example, 50 nm or more and 1000 nm or less.

The sacrificial layer may be a film having an etching rate higher than the etching rate of the material of the semiconductor layer. For example, when GaAs is used as the semiconductor layer, AlGaAs, in particular, AlGaAs having an Al composition ratio of 50% or more and 100% or less can be preferably used. This is because AlGaAs having an Al composition ratio can be easily removed by wet etching with an aqueous hydrofluoric acid solution.
Examples of the method for producing the sacrificial layer include, but are not limited to, MBE, MOCVD, MOPVE, HVPE, and LPE.
The thickness of the sacrificial layer is not particularly limited, but may be, for example, 500 nm or more and 2000 nm or less.

Next, a first interface layer is formed on the sacrificial layer.
Examples of the method for forming the first interface layer include, but are not limited to, MBE, MOCVD, MOPVE, HVPE, and LPE.

After that, the semiconductor layer is formed on the first interface layer.
The semiconductor layer is preferably epitaxially formed by a method such as MBE, MOCVD, MOPVE, HVPE, or LPE.
As the semiconductor layer, a laminated film can be preferably used, but a single-layer film can also be used. When a single-layer film is used, a distribution of impurities is created to form a pn junction in the semiconductor layer.
When the semiconductor layer is used as a laminated film, for example, a plurality of combinations of a Si-doped GaAs layer, an undoped GaAs layer, and an AlGaAs layer are laminated by the MBE method.

After that, a second interface layer is formed on the semiconductor layer.
Examples of the method for forming the second interface layer include, but are not limited to, MBE, MOCVD, MOPVE, HVPE, and LPE.

After that, the first conductor layer is formed on the second interface layer.
Examples of the method for forming the first conductor layer include, but are not limited to, a sputtering method, a heat vapor deposition method, an electron beam vapor deposition method, and a MOCVD method, and are not limited to these methods, and include electrical conductivity, adhesion, and adhesion. Any forming method having excellent surface flatness can be used.

Then, the sample is turned upside down, and the sample is bonded onto the second substrate so that the first conductor layer is in contact with the sample. The second substrate is the substrate of the element 101.
Examples of the bonding method include the Au-Au diffusion bonding method.
In this method, for example, Ti having a thickness of 10 nm and Au having a thickness of 500 nm are laminated and formed on the second substrate. At least the surface side of the first conductor layer is set to Au, and both of them are brought into pressure contact with each other under heating. Examples of the conditions include pressurization of 5 to 10 MPa and temperature of 250 to 330 ° C. for 1 hour.
Here, in order to reduce the stress generated at this time, it is also preferable to continuously apply the heat treatment under the same conditions under no pressure.
As a second bonding method, an epoxy bonding method or the like can be mentioned.
In addition, as other bonding methods, eutectic bonding (soldering, silver wax bonding), anode bonding, surface activation bonding ( ^{cleaning the surface with Ar +} ions under ultra-high vacuum and bonding at room temperature) , Diffusion bonding using Au fine particles and the like can also be mentioned.

The second substrate can be used as long as its surface has flatness and smoothness suitable for bonding. For example, as the second substrate, a GaAs substrate, a Si substrate, an InP substrate, a sapphire substrate, a synthetic quartz glass, a glass substrate such as borosilicate glass and soda lime glass, a ceramics substrate such as alumina and silicon nitride, acrylic and polystyrene (PS). ), Polycarbonate (PP), polyethylene terephthalate (PET), polycarbonate (PC) and other organic material substrates, and metal substrates such as aluminum, iron, stainless steel and copper.

After that, the first substrate is removed by etching, and subsequently, the buffer layer is also removed by etching. These etchings may be mechanical polishing, wet etching, or dry etching.
Then, the sacrificial layer is etched and removed. This etching may be wet etching or dry etching.

After that, a second conductor layer is formed on the exposed first interface layer.
Next, lithography and etching are performed to form a pattern of a light-sensitive portion having a plurality of light-sensitive pieces and a pattern of a wire portion having a plurality of wire pieces on the second conductor layer. Then, the dielectric layer is also etched by using those patterns as a mask.
Here, as the lithography, electron beam lithography, EUV lithography, and nanoimplanting, which are excellent in microfabrication, are preferable, but KrF lithography, ArF lithography, and ArF immersion lithography may also be used. As the etching, dry etching such as reactive ion etching having excellent microfabrication can be preferably used.
Further, in forming the pattern of the second conductor layer, it may be formed by a lift-off method without using etching. That is, a lift-off resist pattern is formed on the dielectric layer by lithography, a second conductor layer is deposited by a sputtering method or a vapor deposition method, and then the resist is removed to have a pattern of a light-sensitive portion and a wire portion. 2 conductor layers may be formed. Since the pattern formation of the dielectric layer is performed by self-alignment with the pattern of the second conductor layer as a mask, problems such as misalignment do not occur. Since the wire piece is thin, this self-alignment formation makes it possible to form a high yield.
Through the above steps, the element 101 having the structure shown in FIG. 1 is manufactured.

(Embodiment 2)
In the second embodiment, elements (infrared light detection element and light emitting element) having enhanced functionality such as directivity and light collection property will be described.
As shown in FIG. 10A, in the element 106 of the second embodiment, the element shown in the first embodiment is arranged in the central portion as a core region 51, and the peripheral region 52 shown below is arranged outside the core region 51. It has a configured structure.
In the peripheral region 52, the second light-sensitive piece and the second wire piece shown below are arranged two-dimensionally. The second light-sensitive piece has a structure in which a dielectric layer and a second conductor layer described in the first embodiment are sequentially laminated on a surface composed of the first conductor layer described in the first embodiment. Have. The second wire piece has a maximum width of more than 0 and L / 5 or less, and connects at least the second conductor layers of the adjacent second light-sensitive pieces with a non-linear portion. It is a wire arranged in a two-dimensional shape. Here, the wire length of the second wire piece changes according to any distance of one-dimensional, two-dimensional, and polar coordinate radii with the center of gravity of the arrangement of the light-sensitive pieces in the core region 51 as the origin. It has become something that has been done. Here, the second wire piece may be arranged at a period P. By fixing the period of the second wire piece to P, there is an effect that the design of the wire length of the second wire piece becomes simple.
Here, the planar shape of the element 106 is not limited to a quadrangle, although both the core region 51 and the peripheral region 52 have a quadrangular outer shape. It may be a circle (element 107) as shown in FIG. 10 (b), or it may be a triangle, a hexagon, or an octagon.

As described in the first embodiment, the core region 51 having the same device structure as the first embodiment exhibits a narrow FOV, a high signal-to-noise ratio, and a high photoelectric conversion efficiency. On the other hand, the peripheral region 52 can impart directivity, light collection, and divergence to the element 106 as a kind of phased array by adjusting the wire length of the second wire piece to control the phase. it can. Here, in order to enhance the light-collecting property to one point (focus) or the divergence property from one point (focus), it is preferable to make the change in the wire length of the second wire piece monotonous.
The elements 106 and 107 of the second embodiment make it possible to provide an element having a high S / N ratio and a high photoelectric conversion efficiency, and having desired directivity, light collecting property, and divergence property.

Further, in the elements 106 and 107 of the second embodiment, the substrate (not shown) is made of a flexible or flexible material such as PET, polycarbonate or rubber, or a membrane made of SiN or the like, and the substrate is bent to give a variable curvature. By expanding and contracting to change the shape of the wire piece in the plane, it can be made into a variable focus element. In this case as well, the core region 51 is formed on a highly rigid substrate to form a fixed region, where a narrow FOV, a high S / N ratio and high photoelectric conversion efficiency are ensured, and the peripheral region 52 is formed on a flexible substrate. It is preferable to perform deformation to give variability. For example, the core region 51 is formed on a relatively thick substrate, and the peripheral region 52 is formed on a thin film substrate, and is deformed by applying pressurization or negative pressure to the substrate like a diaphragm or expanding and contracting the periphery of the substrate. Can be made to.
Wire pieces folded shape of an S-like propagation coefficient k _w is changed by the expansion and contraction, also generally, will also change the interval of the second light-sensitive element, light-collecting plane phase distribution around the region 52 is caused Ya It becomes possible to change the divergence.
In this case, it is preferable to use phosphor bronze, beryllium copper, carbon-containing iron or the like, which are often used as spring materials, for at least the second wire piece because of its high expansion and contraction durability. Further, as the structure of the second wire piece, as shown in FIG. 6, an aerial wiring-like structure in which the dielectric layer 22 is not formed on the portion of the second wire piece is preferable because of its high elasticity.

The present invention is not limited to the above-described embodiment, and the above-described embodiment is an example for explaining the present invention, and is substantially the same as the technical idea described in the claims of the present invention. Anything having the same configuration and exhibiting the same effect and effect is included in the technical scope of the present invention.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not necessarily limited to the following Examples.

(Example 1)
In Example 1, an element according to the first embodiment was produced and its characteristics were evaluated.
First, prior to the experiment, the resonance characteristics of the conventional cavity structure (patch antenna structure) and the resonance characteristics of the structure of the present invention were simulated. The result is shown in FIG. Here, the structure of the device is shown on the left side of FIG. 11, and the light absorption resonance characteristic (relationship diagram between wavelength and light absorption) is shown on the right side.

FIG. 11A is an example of the conventional structure, which is an element 102 in which square cavities having a side width of L, which are light sensitive pieces, are arranged in a matrix with a pitch P. Here, the refractive index of the dielectric layer 22 was assumed to be 3.05 + 0.03i, and the thickness was set to 200 nm. Both the first conductor layer 21 and the second conductor layer 23 are assumed to be made of Au and have a thickness of 100 nm. L is 1.08 μm and P is 2.0 μm. This magnitude and arrangement are values that cause resonance of vertically incident light having a wavelength of 6.7 μm, and peak light absorption is observed at an actual wavelength of 6.7 μm. In this structure, since the light-sensitive pieces are not electrically connected to each other, it is difficult to take out the photoelectrically converted electric signal.

FIG. 11B is an element 103 when the light sensitive piece shown in FIG. 11A is connected by a straight wire piece having a width W of 0.1 μm. The wire piece has a layer structure in which a wire-shaped dielectric layer 22 and a second conductor layer 23 are laminated on the first conductor layer 21. It can be seen that the wavelength at which resonance occurs is shifted to the short wavelength side because the light-sensitive piece is tied with the wire piece. In order to cause resonance at a wavelength of 6.7 μm using a linear wire piece, it is necessary to extend the period P, which increases the size of the element 103.

FIG. 11C is an element 104 when the light sensitive piece shown in FIG. 11A is connected by a Z-shaped wire piece having a width W of 0.1 μm. The layer structure of the wire piece is the same as that of the element 103, and S shown in the figure is 0.45 μm. At a wavelength of 6.7 .mu.m, the propagation constant of the propagation constants _k a = _2.83μm ^-1, portions of the Z-shaped S = 0.45 [mu] m wire piece portion of the photosensitive strip _k w = _3.14μm ^- It is ^1. The structure of this wire piece, for positive integer m = 1, since it is _{k a × L + k w ×} (P-L) -2 × m × π = -0.34, in the above formula (1) there _{| k a × L + k w} × (P-L) -2 × m × π | satisfy ≦ [pi / 2 relationship. As a result, resonance was observed at a wavelength of 6.7 μm, the peak level of the light absorption was higher than that of the element 102, the half width was narrow, and the resonance had a high Q value.
In this structure, since the light-sensitive pieces are electrically connected to each other, the photoelectrically converted electric signal can be taken out. Further, in this structure, the light-sensitive pieces are arranged in a period P, and the light-sensitive pieces are electrically connected to each other while maintaining the period, so that the element 104 is compact.

FIG. 11D is an element 105 when the light sensitive piece shown in FIG. 11A is connected by an S-shaped wire piece having a width W of 0.1 μm. The layer structure of the wire piece is the same as that of the element 103, and S shown in the figure is 0.38 μm. Since the structure of this wire piece is the same as that of FIG. 11 (c), the part of the wire piece having ka = 2.83 μm ^-1 and S-shaped S = 0.38 μm at _{a wavelength of 6.7 μm.} since the propagation constant is the _k w = _3.65μm ^-1, for positive integer _{m = 1, k a × L} + k w × (P-L) -2 × m × π = + 0.13 , and the previously described The relationship of equation (1) is satisfied. As a result, resonance was observed at a wavelength of 6.7 μm, the peak level of the light absorption was higher than that of the element 102, the half width was narrow, and the resonance had a high Q value.
In this structure, since the light-sensitive pieces are electrically connected to each other, the photoelectrically converted electric signal can be taken out. Further, in this structure, the light-sensitive pieces are arranged in a period P, and the light-sensitive pieces are electrically connected to each other while maintaining the period, so that the element 105 is compact.

_{The propagation constant k a} of the light-sensitive piece _{portion and the propagation constant k w} of the wire piece portion of various shapes are obtained by precise numerical calculation. As research progresses in the future, it is expected that reliable values can be obtained at a practical level using an appropriate equivalent circuit picture. In addition, it is thought that it is possible to obtain it experimentally if a special sample is prepared for that purpose, but at present, there is no way to know these values other than relying on numerical calculations. Here, _{the meanings of ka} and k _w and how to obtain them in this study will be explained.
The propagation constant k represents how many radians the phase of the mode of interest in a waveguide structure rotates per unit length. More specifically, when placing the propagation wavelength of the modes within the waveguide structure and lambda _P, it is defined as k = 2π / λ _P. The propagation wavelength is generally different from the wavelength λ in air or vacuum, and in the field of microwave waveguides, λ _P is sometimes called the in-tube wavelength. Here, both the light-sensitive piece and the wire piece are MIM waveguides, and the propagation wavelength λ _P and the propagation constant (also referred to as wave number) k of the TM gap plasmon mode propagating there are discussed in Non-Patent Document 1 and the like. ..

Propagation constant k _a portion of the light-sensitive pieces, consider an infinitely long just before shaped MIM waveguide width L = 1.08 .mu.m, the electric field is polarized in the second direction to the end surface center of the width L, An electric dipole vibrating at a frequency that radiates infrared light having a wavelength of 6.7 μm in a vacuum was arranged, and the electric dipole was obtained as a propagation constant of a propagation mode in which the MIM waveguide propagates in an infinitely continuous longitudinal direction.
The propagation constant of the Z-shaped or S-shaped wire piece portion is infinite in the x direction only for the wire piece portion having a width W extending in the x direction and a length PL in FIGS. 11 (c) and 11 (d). Considering a MIM waveguide made only of wire pieces connected repeatedly, an electric field is polarized in the second direction at the center of the end face of the width W, and emits infrared light having a wavelength of 6.7 μm in a vacuum. An electric dipole that oscillates at the same frequency is arranged, and it is obtained as the propagation constant of the propagation mode in which the MIM waveguide propagates in the infinitely continuous x direction.
Various numerical methods that can solve Maxwell's equation can be used for this calculation, but in this study, the finite element method was used.

Next, an element having the structure shown in FIG. 11 was produced and its characteristics were evaluated. Here, the first conductor layer 21 is a Ti with a thickness of 3 nm and an Au metal layer with a thickness of 150 nm, and the dielectric layer 22 is a GaAs semiconductor layer in which one quantum well having a band structure shown in FIG. 9 is formed. A dielectric layer having a total thickness of 200 nm and a contact layer, and a second conductor layer 23 is a Ti having a thickness of 3 nm and an Au metal layer having a thickness of 100 nm.
For reference, an enlarged SEM photograph of the manufactured element is shown in FIG. 12, and the entire SEM photograph is shown in FIG.

This device was manufactured by the method shown below.
First, a method for producing a quantum well layer will be described. A GaAs (100) substrate to be the first substrate is prepared, the oxide film on the surface thereof is removed by heating at 580 ° C., and then a GaAs buffer for surface flattening is used using an MBE device (COMPACT21T, manufactured by RIBER). The layer was grown to a thickness of 300 nm. Here, the subsequent film containing Ga and As was formed using the same MBE device.
After that, an AlGaAs sacrificial layer having an Al composition of 90% was formed with a thickness of 900 nm, and an AlGaAs sacrificial layer having an Al composition of 55% was formed with a thickness of 100 nm. The formation temperature at this time is 580 ° C.
Subsequently, a total of seven films containing Ga and As were formed as the first contact layer. The first contact layer is a total of 28 nm-thick Si-doped GaAs in which a total of 7 layers of 4 nm-thick Si-doped GaAs (Si: 5 × 10 ¹⁸ / cm ^{3) are laminated, and Si is added each time each layer is formed.} It was δ-doped 7 times in total at 3 × 10 ¹² / cm ^2. The formation temperature after this layer is 530 ° C. Thereafter, the thickness of the volume content of Si in 15nm is 3 × ¹⁰ 18 / cm ³ of GaAs, the thickness was formed undoped GaAs of 5 nm. After the sacrificial layer, the portion having a thickness of 48 nm so far corresponds to the contact layer on the left side of FIG.

After that, in order to form a quantum well structure that plays a central role in the device, an Al _0.3 Ga _0.7 As barrier layer with a thickness of 50 nm and a volume content of Si with a thickness of 4 nm of 3 × 10 ¹⁸ / GaAs quantum well layer of cm ³ (only the last 0.85nm undoped), the thickness was formed _{an Al} 0.3 _{Ga 0.7} As barrier layer of 50nm.
Finally, as the second contact layer on the right side of FIG. 9, ^{a GaAs having a thickness of 15 nm and a volume content of Si of 3 × 10 18} / cm ³ was formed, and then a Si-doped GaAs (Si:) having a thickness of 4 nm was formed. A total of 7 layers of 5 × 10 ¹⁸ / cm ³ ) were laminated, and immediately before forming each layer, Si was ^{delta-doped at 3 × 10 12} / cm ² a total of 7 times.

Next, the formation of the first conductor layer and the step of reversing the quantum well structure using the first conductor layer will be described. On the second contact layer located on the uppermost surface of the quantum well structure, Ti having a thickness of 3 nm and Au having a thickness of 150 nm were formed as a first conductor layer by sputtering. Further, Ti having a thickness of 10 nm and Au having a thickness of 500 nm are formed by sputtering on another GaAs (100) substrate to be a second substrate. The substrate on which the quantum well was formed was turned upside down, the two Au surfaces were brought into contact with each other, and the substrate was heated at 250 ° C. for 60 minutes in a nitrogen gas atmosphere while applying a load of 5 MPa. As a result, the first and second substrates were integrated. Subsequently, the GaAs substrate of the first substrate is mechanically polished leaving about 100 μm, and the remaining GaAs substrate and buffer layer are mixed with a citric acid aqueous solution having a concentration of 1 g / ml and a hydrogen peroxide solution at a ratio of 10: 1. The solution was selectively removed at 38 ° C. to expose the AlGaAs sacrificial layer. Finally, the AlGaAs sacrificial layer was selectively removed with an aqueous hydrofluoric acid solution.

The structure as shown in FIG. 12 was manufactured by an electron beam lithography method, a lift-off method, and a dry etching method. After applying an electron beam resist and drawing a pattern in an area of 100 μm square (this becomes an individual detector) with an electron beam, the pattern corresponding to the second conductor layer is formed by development. The contact layer of 1 was exposed. On it, Ti having a thickness of 3 nm and Au having a thickness of 150 nm were formed as a second conductor layer. By dissolving the resist (lift-off method), a second conductor layer having the expected pattern was formed. Finally, using this second conductor layer as a mask, the dielectric layer was vertically removed by an inductively coupled plasma etching method using a mixed gas of chlorine and nitrogen.
Separately, an electrode pad connected to each 100 μm square detector was formed by a photolithography method and brought into contact with the second conductor layer of each detector. The electrode pad has a size of about 400 μm square with Ti having a thickness of 3 nm and Au having a thickness of 150 nm formed on _{a SiO 2} insulating layer having a thickness of 100 nm.
Finally, the necessary part including the detector and the electrode pad on the second substrate was cut out by cleavage, mounted on the 8-pin ceramic package with conductive epoxy, and each electrode pad was Ag-paste bonded with the pin of the package and Au wire. ..

Next, the characteristics of the manufactured device will be described.
FIG. 14 shows the wavelength dependence of the light absorption rate and the sensitivity of the manufactured infrared light detection element with respect to the vertically incident light. The sensitivity was measured by a Fourier transform infrared spectrophotometer (FT / IR-6200, manufactured by JASCO Corporation). Since it is difficult to directly measure the light absorption rate with vertically incident light, the light absorption rate was calculated as follows. First, infrared light was incident at an angle of 26 ° with respect to vertical incidence, the reflected light was monitored by a micro-Fourier transform infrared spectrophotometer, and the absorption rate was obtained from the reflected light intensity. Then, after confirming that the value matches the simulation value and the result of the simulation is reliable, the simulation for the vertically incident light was performed to calculate the absorption rate. Here, the length L of one side of the actually produced light-sensitive piece is 1.17 μm, the period P is 2.0 μm, the width W of the wire piece is 0.1 μm, and the shape of the wire is Z-shaped (FIG. 11 (FIG. 11). c) (shape), and plotted with S as a parameter.

As described with reference to FIG. 11, the resonance wavelength can be tuned according to the shape of the wire. In FIG. 14, S = 0 μm corresponds to the straight wire of FIG. 11 (a), and as seen there, the resonance wavelength is the shortest at this time. As S increases, the wire becomes longer, and the resonance wavelength becomes longer accordingly. In FIG. 14, when S = 0.29 μm, the resonance wavelength coincided with the light absorption wavelength (electronic resonance) 6.7 μm peculiar to the quantum well, and the maximum sensitivity was obtained. At this time, in addition to the optical resonance of each light-sensitive piece, a double optical resonance is generated by electrically connecting the light-sensitive pieces with a wire piece having a non-linear portion, thereby causing a wavelength of 6.7 μm. It can be seen that triple resonance is realized at this point, and extremely high light absorption and extremely high sensitivity can be obtained. The maximum sensitivity observed individually is 3.3 A / W, which is 61% in terms of quantum efficiency. This is a value comparable to the HgCdTe detector currently exclusively used as a high-sensitivity detector in these wavelength ranges. However, since the detector according to the present invention does not use toxic elements such as Hg and Cd, it can be said that the present invention is also highly valuable in that it can replace the conventional toxicity detector with a low toxicity material.

FIG. 15 shows the infrared light incident angle dependence of the detection sensitivity. The angle of incidence when the normalization sensitivity is 0.5 represents FOV / 2.
Here, in the structure of the present invention, the light-sensitive piece L is 1.17 μm, P is 2.0 μm, the width of the wire piece is 0.1 μm, the shape is Z-shaped, and S is 0.45 μm.
The prior art is an element 102 in which only the square light-sensitive pieces having an L side shown in FIG. 11A are arranged in a matrix with a period P. Here, L is 1.17 μm and P is 2.0 μm. It is not possible to actually extract a current signal only with a square light-sensitive piece that is not connected by a wire. The results shown here are virtual results obtained by simulation to clarify the effect of the presence of the wire piece on the angle of incidence dependence.
The FOV of the element 102 of the prior art is as wide as 117 °, whereas in the case of the present invention, the FOV is as narrow as 66 °, which is about half. Since the FOV is narrow, the element of the present invention is difficult to pick up noise due to background light (heat radiation from the surroundings).

FIG. 16 shows the polarization dependence of the detector sensitivity.
Here, in the structure of the present invention, the light-sensitive piece L is 1.17 μm, P is 2.0 μm, the width of the wire piece is 0.1 μm, the shape is Z-shaped, and S is 0.45 μm.
The prior art in this figure is a Brewster's angle incident detector, which uses the same quantum well but has no absorption enhancement due to any cavity. A conventional detection element for infrared light using a quantum well employs an oblique incident structure in order to obtain incident light (defined as a polarization angle of 0 °) in which an electric field is polarized in the second direction. Brewster's angle incidence is one form of this, in which the incident light efficiently captures light at a special angle that efficiently penetrates into the quantum well without reflection on the surface. However, since the quantum well has no sensitivity to the incident light (polarization angle 90 °) polarized in the orthogonal direction, the polarization dependence has always been a problem. FIG. 16 shows the situation by actual measurement.
In the device of the prior art, the sensitivity decreases monotonically from 0 ° to 90 ° and becomes almost zero at 90 °, whereas in the case of the present invention, it hardly changes from 0 ° to 90 °. By adopting a 4-fold symmetric structure, the polarization dependence is eliminated and the maximum sensitivity to any incident light can be exhibited.

FIG. 17 shows the environmental temperature dependence of the detection sensitivity. In this figure, the shape of the characteristic curve and the position of the peak wavelength are normalized and plotted in order to compare them. It can be seen that this device has sensitivity not only at 78K but also at 293K (20 ° C.). This is because the quantum well is incorporated in the patch antenna structure (cavity structure utilizing half-wavelength resonance in TM gap plasmon mode) to enhance the sensitivity.

(Example 2)
In Example 2, the characteristics of the device according to the second embodiment were evaluated.
Here, it is shown that an infrared light detection element having a particularly strong sensitivity to a spherical wave having a specific curvature can be realized by a structure in which the wire gradually becomes longer from the center. Based on the structure shown in FIG. 11 (d). A wire piece having an _{S value of S 0} in FIG. 11D is connected to the central light sensitive piece in four directions. A wire piece is connected to the outer region so that the value of S gradually increases according to the horizontal and vertical distances from the center. This makes it possible to strongly resonate with wavefronts having different phases locally.

L is 1.08 μm, P is 2.0 μm, and W is 0.1 μm. The refractive index of the dielectric layer 22 was assumed to be 3.05 + 0.03i, and the thickness was 200 nm. Both the first conductor layer 21 and the second conductor layer 23 are assumed to be made of Au and have a thickness of 100 nm. Although FIG. 18 is a schematic view, the actually examined structure is a complicated one in which 19 × 19 light-sensitive pieces 12 are arranged. The central light-sensitive pieces to the 0th, X and Y directions respectively the i-th light-sensitive pieces (i + 1) th value of S in wire piece which connects the light sensitive element and S _i. Specifically, S ₀ = 0.25 μm, S ₁ = 0.30 μm, S ₂ = 0.35 μm, S ₃ = 0.38 μm, S ₄ = 0.41 μm, S ₅ = 0.43 _{μm, S 6} = It was selected to increase monotonically, such as 0.44 μm, S ₇ = 0.45 μm, S ₈ = 0.46 _{μm, and S 9 = 0.47 μm.} All the wire pieces at the same position in the X direction were selected to have the same S value, and all the wire pieces at the same position in the Y direction were selected to have the same S value.
Here, the central light-sensitive piece 12 and _{the four wire pieces whose S values are S 0} are connected in the X-direction and the Y-direction, and up to the four light-sensitive pieces 12 arranged in the period P, in the center. The region surrounded by the five light-sensitive pieces 12 satisfies the condition of the equation (1).

At this time, FIG. 19 shows the relationship between the position of the light source and the sensitivity of the detection element when the point light source that emits infrared light having a wavelength of 6.1 μm is at a distance Zs from the surface of the first conductor layer. The maximum sensitivity is obtained at Zs = 10 μm, which means that this detection element has a specific strong sensitivity to spherical waves having a radius of curvature of 10 μm.
When this structure is used for the light emitting element for infrared light, light rays that strongly focus infrared light of a specific wavelength at a specific focal position from an ultrathin light emitting element or emitted light rays are used without using a lens. Can be emitted.

INDUSTRIAL APPLICABILITY The present invention provides a compact detection element and light emitting element for infrared light having a high signal-to-noise ratio and high photoelectric conversion efficiency.
Infrared light detection elements are in strong demand in the fields of motion sensors, surveillance sensors, temperature sensors, gas sensors, etc., where both small size and high S / N ratio and high detection sensitivity are required.
Further, infrared light emitting elements are in strong demand in fields such as gas sensors, and there is a demand for both high directivity and strong light emitting intensity.
The detection element and the light emitting element according to the present invention satisfy the above performance and are considered to be industrially beneficial.

11 Light-sensitive part 12 Light-sensitive piece 13 Wire part 14, 14a, 14b, 14c Wire piece 21 First conductor layer 22 Dielectric layer 23 Second conductor layer 51 Core area 52 Peripheral area 53 Core area 54 Peripheral area 101, 102, 103, 104, 105, 106, 107 elements

Claims (21)

An element that detects or emits infrared light with a peak wavelength of λ.
The element has at least a light-sensitive portion that is sensitive to the infrared light and a wire portion that makes an electrical connection.
The light-sensitive portion is composed of a plurality of light-sensitive pieces having a planar shape of main size L arranged two-dimensionally with a period P.
The light-sensitive piece has a layer structure in which a dielectric layer and a second conductor layer are sequentially laminated on a surface made of a first conductor layer.
The thickness T of the dielectric layer is more than 0 and less than λ / (2n) when the refractive index of the dielectric layer with respect to λ is n.
Area of the light-sensitive strip is ² or less {3λ / ^{(8n)} 2} or {5λ / ^(8n)},
The wire portion connects at least the second conductor layers of the adjacent light-sensitive pieces with a non-linear portion, and has a maximum width of more than 0 and L / 5 or less. Consists of
The element has an in-plane propagation mode in which the photosensitizer and the wire piece propagate in the first direction, which is the direction of the arrangement, and are polarized in the second direction, which is the direction perpendicular to the plane. And
With respect to the infrared light incident from the second direction.
_{| k a × L + k w} × (P-L) -2 × m × π | ≦ π / 2 (m is a positive integer)
There relationship, a positive propagation constant portion and portions of the wire piece of the light-sensitive strip of the propagation modes traveling in the first direction when a k _a, k _w respectively,
An element in which the planar shape of the functional portion including the light-sensitive portion and the wire portion has symmetry of three times or more. The element according to claim 1, wherein the dielectric layer includes a semiconductor layer. The semiconductor layer is composed of Si, Ge, AlAs, GaAs, InAs, AlSb, GaSb, InSb, AlP, GaP, InP, AlN, GaN, InN, PbS, PbSe, ZnTe, CdTe, HgTe, ZnSe, CdSe, MgSe. The element according to claim 2, which comprises one or more selected from the group. The element according to claim 2, wherein the semiconductor layer includes a quantum well. The element according to claim 4, wherein the number of the quantum wells is 1 or more and 5 or less. The device according to claim 4, wherein the number of the quantum wells is 1. The quantum wells are GaAs and AlGaAs, InGaAs and InAlAs, InGaAs and InP, InGaAs and AlAsSb, InGaAsP and InP, GaAs and GaInP, GaAs and AlInP, GaN and AlGaN, GaN and AlN, InAs and AlAsSb, ZnCdSe and ZnCdMgSe, InAs. The element according to any one of claims 4 to 6, which comprises 1 or more selected from the group consisting of GaSb, InAs and GaInSb, InAs and InAsSb, InGaAs and GaAsSb, and InAs and AlGaSb. The element according to any one of claims 1 to 7, wherein the first conductor layer and the dielectric layer, and the dielectric layer and the second conductor layer are both in ohmic contact. The element according to claim 1, wherein the dielectric layer is made of an insulator. The dielectric layer is diamond, Si, Ge, MgO, Al ₂ O ₃ , SiO ₂ , BeO, CaO, TiO ₂ , Ti ₂ O ₃ , TiO, V ₂ O ₅ , Cr ₂ O ₃ , MnO, Cu _2. O, CuO, ZnO, Sc ₂ O ₃ , Y ₂ O ₃ , ZrO ₂ , Ga ₂ O ₃ , Nb ₂ O ₅ , SnO ₂ , CeO ₂ , HfO ₂ , Ta ₂ O ₅ , LiF, NaF, MgF ₂ , _{AlF 3, CaF 2, SrF 2} , YF 3, CsF, BaF 2, LaF 3, CeF 3, NdF 3, GdF 3, YbF 3, PbF 2, ThF 4, ZnS, ZnSe, ZnTe, CdSe, CdTe, AgGaS 2 , AgGaSe ₂ , Zn ₃ P ₂ , ZnGeP ₂ , As ₂ S ₃ , As ₂ Se ₃ , AlAs, AlSb, GaP, GaAs, GaSb, GaSe, GaTe, InP, SiC, BN, AlN, GaN, NaCl, KCl, 1 or more selected from the group consisting of AgCl, CsCl, KBr, RbBr, AgBr, CsBr, KI, RbI, AgI, CsI, TlI, TlBr, CaCo ₃ , _{SrTIO 3} , LiTaO ₃ , ZrSiO ₄ , KNbO ₃ Item 1. The element according to item 1. The first conductor layer and the second conductor layer are Ti, Cr, Ni, Au, Pt, Ag, Pd, W, Cu, Yb, Sm, Y, Tb, Ho, Tm, Gd, Er. , Nd, Sc, Zr, Hf, Ta, Nb, V, Fe, Mo, Ru, Co, Rh, Re, Ir, In, Al, one or more metals selected from the group consisting of Ti, Cr, Ni, Au. , Pt, Ag, Pd, W, Cu, Yb, Sm, Y, Tb, Ho, Tm, Gd, Er, Nd, Sc, Zr, Hf, Ta, Nb, V, Fe, Mo, Ru, Co, Rh , Re, Ir, In, Al alloys containing one or more metals selected from the group consisting of, Ti, Cr, Ni, Au, Pt, Ag, Pd, W, Cu, Yb, Sm, Y, Tb, Ho, A compound containing one or more metals selected from the group consisting of Tm, Gd, Er, Nd, Sc, Zr, Hf, Ta, Nb, V, Fe, Mo, Ru, Co, Rh, Re, Ir, In and Al. , And the element according to any one of claims 1 to 10, comprising any of ITO, AZO, GZO, IZO, IGZO, ATO, FTO, FZO, and TiN. The element according to any one of claims 1 to 11, wherein the plane shape of the light-sensitive piece is 1 selected from the group consisting of an equilateral triangle, a square, a regular hexagon, a regular octagon, and a perfect circle. The planar shape of the light-sensitive piece is a square whose size is L.
Wherein L, when the lowest order of the effective refractive index of in-plane propagation modes polarized in the second direction of the light-sensitive element was _{n eff, 3λ / (8n eff} ) or 5λ / _{(8n eff)} below And
The effective refractive index n _eff ^{is n · (1 + 2δ / T) 1/2} , where δ is the average skin depth of the first conductor layer and the second conductor layer, claim 1. The element according to any one of 1 to 11. The element according to any one of claims 1 to 13, wherein the planar shape of the wire piece includes a right-angled portion. The element according to any one of claims 1 to 14, wherein the symmetry is four-fold symmetry. The element according to any one of claims 1 to 15, wherein the arrangement is in the form of a matrix. The element according to any one of claims 1 to 16, wherein at least a plurality of second conductor layers of the light-sensitive pieces are formed above the first conductor layer. The element according to any one of claims 1 to 17, wherein at least a plurality of second conductor layers of the light-sensitive pieces are formed on the dielectric layer. On the outside of the infrared light detection element and the light emitting element according to any one of claims 1 to 18.
A second light-sensitive piece in which the dielectric layer and the second conductor layer are sequentially laminated on a surface made of the first conductor layer.
A second wire having a maximum width of more than 0 and L / 5 or less, which connects at least the second conductor layers of the adjacent second light-sensitive pieces with a non-linear portion. The pieces are arranged in two dimensions,
The wire length of the second wire piece varies according to any distance of one-dimensional, two-dimensional, and polar coordinate radii with the center of gravity of the arrangement of the light-sensitive pieces as the origin. Item 1. The element according to any one of Items 1 to 16. The element according to claim 19, wherein the second wire piece is arranged in the period P. The element according to claim 19 or 20, wherein the change in wire length is monotonous.

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