JP2024003684A - Photonic crystal and infrared optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photonic crystal and an infrared optical device which can be widely used in a mid-infrared light region.

SOLUTION: The photonic crystal includes a periodic structure made in plural regions containing impurities in different concentrations, and is made of Al_xGa_yIn_1-x-yAs_zSb_1-z (0≤x+y≤0.5, 0≤z≤1.0). The periodic structure may have a periodicity in three different directions which are not in the same flat surface. The material may be Al_xGa_yIn_1-x-yAs_zSb_1-z (0≤x+y≤0.5, 0≤z≤0.5).

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2024,JPO&INPIT

Description

TECHNICAL FIELD This disclosure relates to photonic crystals and infrared light devices.

Generally, infrared rays in a long wavelength band of 2 μm or more are used in human sensors, non-contact temperature sensors, gas sensors, etc. that detect the human body because of their thermal effects and the effects of infrared absorption by gases. In particular, infrared rays in the short, medium, and long wavelength infrared regions (referred to as the mid-infrared region), which have wavelengths of about 2 to 15 μm, are non-dispersed infrared absorbers because gas molecules exhibit a unique absorption band. It has been used in type gas concentration measuring devices. Among these, infrared light devices are important components that greatly influence the main performance of gas concentration measuring instruments, such as detection resolution and power consumption, and infrared light devices with high emission intensity or light reception sensitivity at desired wavelengths are required. It's here. Here, the optical device means a light emitting element or a light receiving element. For example, a light emitting diode (LED) is used as the light emitting element. Further, for example, a photodiode (PD) is used as the light receiving element. Infrared light devices using such semiconductors are capable of receiving and emitting light in a desired wavelength band depending on material design, and have been used in gas concentration measuring instruments.

However, at present, analytical instruments that use infrared light devices have not become widely used. One of the reasons for this is that known infrared light devices do not provide sufficient light emission intensity or light reception sensitivity, and therefore, sufficient signal strength (S/N ratio) cannot be obtained for the analytical instrument as a whole.

Generally, one of the reasons why the light emission intensity of an LED becomes low is that the light extraction efficiency is low. As a method of increasing light extraction efficiency, a method using a photonic crystal having a period comparable to the wavelength of light is known. A photonic crystal is a crystal with a periodic refractive index distribution, and is characterized by the formation of a band structure with respect to photon energy. By appropriately designing the band structure of a photonic crystal, the transmittance or reflectance of a desired wavelength can be controlled.

For example, Patent Document 1 discloses a method of improving the light extraction efficiency of an LED by forming a photonic crystal on a light exit surface. Moreover, Patent Document 2 discloses a method of improving light extraction efficiency by forming a reflective photonic crystal on a surface of a light-emitting layer opposite to a light-emitting surface.

International Publication No. 2013/008556 International Publication No. 2015/133000

A photonic crystal periodic structure is formed at an interface between two structures having different refractive indexes, and generally has irregularities mainly consisting of a pillar structure or a hole structure. However, dry etching is often used to form unevenness, and there is a problem in that the layer to be etched is damaged and the characteristics of the optical device are deteriorated. Furthermore, since the surface of the compound semiconductor layer is uneven, problems may occur in the coverage and uniformity of the protective film formed on the semiconductor surface.

The present disclosure has been made in view of these circumstances, and an object of the present disclosure is to provide a photonic crystal and an infrared optical device that can be widely used in the mid-infrared region.

(1) The photonic crystal according to an embodiment of the present disclosure is
It has a periodic structure composed of multiple regions with different impurity concentrations,
The constituent material is Al _x Ga _y In _1-x-y As _z Sb _1-z (0≦x+y≦0.5, 0≦z≦1.0).

(2) As an embodiment of the present disclosure, in (1),
The periodic structure has periodicity in three different directions that are not on the same plane.

(3) As an embodiment of the present disclosure, in (1) or (2),
The constituent material is Al _x Ga _y In _1-xy As _z Sb _1-z (0≦x+y≦0.5, 0≦z≦0.5).

(4) As an embodiment of the present disclosure, in any one of (1) to (3),
The periodic structure consists of a low refractive index region and a high refractive index region,
The low refractive index region includes an N-type semiconductor region having an impurity concentration of 1.0×10 ¹⁸ /cm ³ or more,
The high refractive index region includes at least one of a P-type semiconductor region, an intrinsic semiconductor region, and an N-type semiconductor region having a lower impurity concentration than the N-type semiconductor region of the low refractive index region.

(5) As an embodiment of the present disclosure, in (4),
The low refractive index region includes an N-type semiconductor region having an impurity concentration of 3.0×10 ¹⁸ /cm ³ or more.

(6) As an embodiment of the present disclosure, in (4) or (5),
The high refractive index region includes at least one of a P-type semiconductor region, an intrinsic semiconductor region, and an N-type semiconductor region having an impurity concentration of less than 3.0×10 ¹⁷ /cm ³ .

(7) As an embodiment of the present disclosure, in any one of (1) to (6),
It is provided on a substrate and has a periodic structure having periodicity in the plane direction of one main surface of the substrate.

(8) The infrared light device according to an embodiment of the present disclosure includes:
A substrate and
a light receiving and emitting layer that receives or emits infrared light;
A photonic crystal according to any one of (1) to (7) is provided.

(9) As an embodiment of the present disclosure, in (8),
The bandgap of the constituent material of the photonic crystal is larger than the bandgap of the light emitting/receiving layer.

(10) As an embodiment of the present disclosure, in (8) or (9),
It has an entrance/exit surface that emits or enters infrared rays, and the photonic crystal is formed on the side of the entrance/exit surface with respect to the light emitting/receiving layer.

(11) As an embodiment of the present disclosure, in (10),
The photonic crystal is formed on the input/output surface.

(12) As an embodiment of the present disclosure, in any one of (8) to (11),
A distance between the photonic crystal and the light emitting/receiving layer is within one wavelength of light corresponding to a band gap of the light emitting/receiving layer.

(13) As an embodiment of the present disclosure, in (8) or (9),
It has an entrance/exit surface that emits or enters infrared rays, and the photonic crystal is formed on the opposite side of the entrance/exit surface with respect to the light receiving/emitting layer.

According to the present disclosure, it is possible to provide a photonic crystal and an infrared optical device that can be widely used in the mid-infrared region. Infrared light devices can have strong light emitting or light receiving characteristics in the mid-infrared wavelength range.

FIG. 1 is a diagram illustrating the structure and formation method of a photonic crystal. FIG. 2 is a diagram illustrating the arrangement and shape of regions in a photonic crystal. FIG. 3 is a diagram illustrating the arrangement and shape of regions in a photonic crystal. FIG. 4 is a diagram illustrating the shape of a region in a photonic crystal. FIG. 5 is a diagram illustrating the shape of a region in a photonic crystal. FIG. 6 is a diagram illustrating two-level regions in a photonic crystal. FIG. 7 is a diagram illustrating two-level regions in a photonic crystal. FIG. 8 is a diagram illustrating the structure and formation method of a photonic crystal. FIG. 9 is a diagram illustrating point defects in a photonic crystal. FIG. 10 is a diagram illustrating the arrangement of photonic crystals in an infrared light device. FIG. 11 is a diagram illustrating the arrangement of photonic crystals in an infrared light device. FIG. 12 is a diagram illustrating the arrangement of photonic crystals in an infrared light device. FIG. 13 is a diagram illustrating the arrangement of photonic crystals in an infrared light device. FIG. 14 is a diagram showing the dependence of the refractive index of the InSb layer on the n-type impurity concentration.

Embodiments of the present disclosure will be described below with reference to the drawings. However, the drawings are schematic. For example, the thickness, length, period, etc. are different from the real thing. The technical idea of the present disclosure can be modified in various ways within the technical scope defined by the claims. The following embodiments do not limit the content of this disclosure. Furthermore, not all combinations of features described in the embodiments are essential to the solution.

<Photonic crystal>
The photonic crystal according to this embodiment has Al _x Ga _y In _1-x-y As _z Sb _1-z (0≦x≦0.5, 0≦y≦0.5, 0≦x+y≦0.5 , 0≦z≦1.0), and has a periodic structure composed of a plurality of regions having mutually different impurity concentrations. The inventors of the present disclosure have discovered that the refractive index can be broadly controlled in the mid-infrared region by doping a material with impurities and controlling the impurity concentration (carrier concentration). Here, the carrier concentration is determined by the impurity concentration and activation rate.

The low refractive index region is formed including an N-type semiconductor region having an impurity concentration of 1.0×10 ¹⁸ /cm ³ or more.

Further, the high refractive index region is formed including at least one of a P-type semiconductor region, an intrinsic semiconductor region, and an N-type semiconductor region. When an N-type semiconductor region is used as the high refractive index region, an N-type semiconductor region having a lower impurity concentration than the N-type semiconductor region of the low refractive index region can be used. As the P-type semiconductor region, for example, a semiconductor region having an impurity concentration of 1.0×10 ¹⁶ /cm ³ to 1.0×10 ¹⁹ /cm ³ can be used.

The low refractive index region may include an N-type semiconductor region having an impurity concentration of 1.5×10 ¹⁸ /cm ³ or more. Further, the low refractive index region preferably includes an N-type semiconductor region having an impurity concentration of 3.0×10 ¹⁸ /cm ³ or more, and by setting the impurity concentration to 4.0×10 ¹⁸ /cm ³ or more. , the refractive index can be further lowered.

When using an N-type semiconductor region as a high refractive index region, it is necessary to have an impurity concentration lower than the impurity concentration of the low refractive index region as described above, and less than 1.5 × 10 ¹⁸ /cm ³ More preferably, it includes an N-type semiconductor region. Furthermore, the refractive index of the high refractive index region can be further increased by setting the impurity concentration of the N-type semiconductor region to less than 8.0×10 ¹⁷ /cm ³ . The high refractive index region may include, for example, an N-type semiconductor region with an impurity concentration of less than 3.0×10 ¹⁷ /cm ³ and further may have an impurity concentration of less than 1.0×10 ¹⁷ /cm ³ .

A periodic structure in which these low refractive index regions and high refractive index regions are periodically arranged makes it possible to form a photonic crystal.

Here, as impurities, for example, Sn and Te are used as n-type doped materials, and Zn, Be, and Ge are used as p-type doped materials. Further, Si is used as an n-type or p-type dopant material depending on the base semiconductor. However, the impurity materials are not limited to these. The impurity concentration can be evaluated by, for example, secondary ion mass spectrometry (SIMS).

By forming a plurality of regions with different impurity concentrations (that is, impurity doping concentrations), regions with different refractive indexes are formed. The different regions may be of different materials or the same material with only different impurity doping concentrations.

As in this embodiment, Al _x Ga _y In _1-x-y As _z Sb _1-z can be formed on the substrate. Here, as the substrate, for example, a Si substrate, a GaAs substrate, an InP substrate, an InSb substrate, an InAs substrate, a GaSb substrate, etc. can be used.

A plurality of regions having different impurity concentrations can be formed, for example, as follows. Impurities are introduced into Al _x Ga _y In _1-x-y As _z Sb _1-z by ion implantation or thermal diffusion treatment using a patterned photoresist as a mask. Thereby, a region doped with a predetermined impurity can be formed (FIG. 1). In FIG. 1, the mask is shown as a small white square, and the regions into which impurities have been introduced are shown in color. In FIGS. 2 to 13 as well, regions into which impurities have been introduced are shown in color. Further, a treatment such as annealing may be performed to activate impurities. Thereby, when a photonic crystal is provided on a substrate, it is possible to easily form a periodic structure having periodicity in the plane direction of one main surface of the substrate (direction along the main surface). This corresponds to a so-called two-dimensional photonic crystal.

Here, common orthogonal coordinates are set in FIG. 1 and FIGS. 2 to 13, which will be described later. In this embodiment, the z-axis direction is an axial direction perpendicular to the main surface of the substrate. The x-axis direction and the y-axis direction are directions in which the photonic crystal described above has periodicity. For example, FIG. 1 shows a periodic structure along the x-axis direction, and the two-dimensional photonic crystal similarly has a periodic structure along the y-axis direction (for example, see FIG. 2). Furthermore, in this embodiment, the xy plane is parallel to the main surface of the substrate. The line of sight direction in which the xy plane is viewed from the front may be referred to as a planar view below.

Returning to FIG. 1, after patterning a photoresist for Al _x Ga _y In _1-x-y As _z Sb _1-z , which is an intrinsic semiconductor that is not doped with impurities, ion implantation is performed to a predetermined depth. n-type impurity is introduced. By this method, it is possible to form a photonic crystal in which the region into which the n-type impurity is introduced is a low refractive index region, and the region into which the n-type impurity is not introduced is a high refractive index region. Here, the material into which impurities are introduced is sometimes referred to as the constituent material of the photonic crystal. In this embodiment, the constituent materials are Al _x Ga _y In _1-xy As _z Sb _1-z .

As a similar example, after patterning a photoresist for Al _x Ga _y In _1-x-y As _z Sb _1-z , which is a p-type semiconductor doped with p-type impurities, a predetermined depth is formed by ion implantation. Only a small amount of n-type impurity is introduced. This method also makes it possible to form a photonic crystal in which the region into which the n-type impurity is introduced is a low refractive index region, and the region into which the n-type impurity is not introduced is a high refractive index region. That is, by introducing an n-type impurity at a concentration higher than the original p-type impurity concentration, a low refractive index region can be formed.

The doped or undoped regions may be arranged in any shape. For example, the impurity-doped regions may be arranged in a square lattice shape (FIG. 2) or a triangular lattice shape (FIG. 3) in plan view.

The doped or undoped regions may have any shape. For example, the impurity-doped region may be circular (FIGS. 2 and 3), triangular (FIG. 4), or square (FIG. 5) in plan view.

The region doped with impurities or the region not doped with impurities may be formed with two or more different impurity concentrations (FIG. 6).

For example, a doped region may be formed in a circular shape in a plan view, and outside the doped region, a region doped with different concentrations may be formed in an annular shape in a plan view (FIG. 7).

When a photonic crystal is provided on a substrate, a periodic structure having periodicity also in the direction perpendicular to the substrate (z-axis direction) can be formed, for example, as follows. After forming a plurality of regions having mutually different impurity concentrations as described above, the constituent material Al _x Ga _y In _1-xy As _z Sb _1-z is grown again. Before growth, the surface may be flattened by CMP (Chemical Mechanical Polishing) or the like. After the growth, a plurality of regions having mutually different impurity concentrations are formed again. By performing this process a certain number of times, it is possible to easily form a periodic structure that also has periodicity in the direction perpendicular to the substrate. This corresponds to a so-called three-dimensional photonic crystal (Figure 8).

The doped or undoped regions can be coincident with the underlying layer. For example, by doping impurities in a square lattice shape, and after regrowing the constituent materials, doping the impurities in a square lattice shape at the same position as the layer below in plan view, a three-dimensional photonic crystal in a cubic lattice shape is formed. can do.

Here, there is no need for the doped or undoped regions to coincide with the underlying layer. By freely designing the impurity doping position according to the design of the photoresist mask, a three-dimensional photonic crystal can be designed arbitrarily. For example, a three-dimensional photonic crystal having a body-centered cubic lattice structure or a hexagonal close-packed structure can be formed. In this way, a periodic structure consisting of a unit cell having basic translation vectors in three different directions that are not on the same plane can be formed. In other words, the periodic structure of the three-dimensional photonic crystal is formed to have periodicity in three different directions that are not on the same plane.

Here, the presence or absence of local impurity doping can be freely designed by designing the photoresist mask. For example, point defects can be introduced by not doping only a portion of the layer when repeating regrowth and doping as described above (FIG. 9). With this design, defects such as so-called line defects or point defects can be introduced into the photonic crystal, and optical waveguides or optical confinement can be performed.

Further, as another method for forming a three-dimensional photonic crystal, there is a method in which it is formed only by ion implantation without performing regrowth. Ion implantation is a method of doping impurities by accelerating ionized impurities at high speed and implanting them into a sample. At this time, the depth into which the impurity is implanted changes depending on the acceleration energy. Therefore, by implanting impurities multiple times using different acceleration energies, it is possible to implant impurities into multiple different depth regions. Thereby, a three-dimensional photonic crystal can be formed without regrowth.

The photonic crystal according to this embodiment has a periodic structure composed of a plurality of regions having mutually different impurity concentrations. However, the periodic structure in this embodiment is not intended to completely match the positions, sizes, or doping concentrations of a plurality of adjacent regions.

For example, the positions or sizes of a plurality of adjacent regions may be modulated. Additionally, defects such as line defects or point defects may be introduced as described above. Similarly, the dope concentration may be partially modulated.

In addition, _the photonic _{crystal according} to _the present embodiment _has Al .5, 0≦z≦1.0).

Here _, by narrowing _the composition _{range of} As _{in Al} Ga _y In _1-xy As _z Sb _1-z (0≦x+y≦0.5, 0≦z≦0.3) may be used. In addition _, narrowing the composition range of Al _{and Ga} enables better crystal growth and improves the performance _of infrared light devices _. 0≦x+y≦0.3, 0≦z≦0.3) may be used. Furthermore, Al _x Ga _y In _1-x-y As _z Sb _1-z (0≦x+y≦0.2, 0≦z≦0.2) may be used. Further, for example, by using a quaternary mixed crystal in which y indicating the Ga composition is 0, a simple structure whose structure can be more easily controlled can be obtained.

Al _x Ga _y In _1-x-y As _z Sb _1-z can be formed by various methods such as MBE or MOCVD. In order to reduce dislocation defects, so-called dislocation filter layers may also be introduced.

<Infrared light device>
By using the above-described photonic crystal, the characteristics of an infrared light device can be improved. For example, the light emission intensity of a light emitting diode (LED) can be improved. Further, for example, the light receiving sensitivity of a photodiode (PD) can be improved. Here, the infrared light device is an infrared light emitting element or an infrared light receiving element, and is a collective name for these elements.

A photonic crystal has a periodic structure of refractive index. Therefore, the dispersion relationship of light waves takes a so-called photonic band structure. This is very different from the dispersion relationship in normal media, and it exhibits various functions not seen in normal media. For example, it is possible to form a wavelength range in which light propagation is impossible, a so-called photonic bandgap. The photonic bandgap is determined by the refractive index of the material, the periodic length of the periodic structure, etc.

For example, in the case of a two-dimensional photonic crystal, by utilizing a condition called a light cone, light is no longer confined within the photonic crystal, so the light extraction efficiency, that is, the light transmittance, can be improved. In the following, a photonic crystal having the function of improving transmittance in this manner will be referred to as a "transmission type photonic crystal."

For example, light within the photonic bandgap is not allowed to propagate within the photonic crystal. Such photonic crystals can improve reflectance. In the following, a photonic crystal having the function of improving reflectance in this manner will be referred to as a "reflection type photonic crystal."

The infrared light device according to this embodiment includes a substrate, a light receiving/emitting layer that receives or emits infrared light, and a photonic crystal. _{The photonic crystal} has a constituent material _{of Al} It has a periodic structure consisting of regions. Further, the infrared light device has an infrared input/output surface.

The entrance/exit surface is an entrance surface or an exit surface, and is a collective name for these. That is, the entrance/exit surface is an exit surface that emits infrared rays or an entrance surface that enters infrared rays. Further, the light-receiving and emitting layer is a light-receiving layer or a light-emitting layer, and is a collective name for these layers. That is, the light receiving and emitting layer is a light emitting layer that emits infrared light in an optical device that is a light emitting element, or a light receiving layer that receives infrared light in an optical device that is a light receiving element.

In order to suppress light absorption within the photonic crystal, it is preferable that the band gap of Al _x Ga _y In _1-x-y As _z Sb _1-z constituting the photonic crystal is larger than the energy corresponding to the desired wavelength. . In optical devices, the emission wavelength or reception wavelength often corresponds to the bandgap of the light emitting/receiving layer. Therefore, it is preferable that the band gap of Al _x Ga _y In _1-x-y As _z Sb _1-z constituting the photonic crystal is larger than the band gap of the light emitting/receiving layer.

By forming a transmissive photonic crystal on the infrared incident/exit surface, the light transmittance, that is, the light extraction efficiency can be improved as described above, and the emission intensity of the LED can be improved (FIG. 10). Even in PDs, the difference in refractive index between air and the device can be suppressed gently, so reflection can be suppressed and light-receiving sensitivity can be improved.

Furthermore, the transmission type photonic crystal does not necessarily need to be formed on the incident/exit surface as long as it is formed on the incident/exit surface side with respect to the light receiving/emitting layer (FIG. 11). For example, internal reflection at the interface can be suppressed by forming a transmissive photonic crystal at the interface of materials with significantly different refractive indexes inside the device.

In the case of a two-dimensional photonic crystal, by appropriately designing a photonic band, it is possible to generate a standing wave of light of a desired wavelength within a plane in which a periodic structure is formed.

At this time, by bringing the spatial distance between the light emitting/receiving layer and the photonic crystal closer, improvements in characteristics can be expected.

For example, in the case of a PD, by localizing incident light as a standing wave within a photonic crystal and arranging a light-receiving layer near the photonic crystal, it is possible to efficiently absorb the incident light and improve light-receiving sensitivity. For example, in the case of an LED, by using light emitted from the active layer as a standing wave in the photonic crystal and increasing the electric field intensity, it is possible to increase the intensity of light emitted from the light emitting layer due to the Purcell effect. Here, regarding the neighborhood arrangement, it is preferable that the distance between the photonic crystal and the light emitting/receiving layer is within one wavelength of the desired wavelength within the substance. As described above, in optical devices, the emission wavelength or reception wavelength often corresponds to the bandgap of the light emitting/receiving layer. Therefore, in other words, it is preferable that the distance between the photonic crystal and the light emitting/receiving layer is within one wavelength of the light corresponding to the band gap of the light emitting/receiving layer.

Further, by forming a reflective photonic crystal on the opposite side of the infrared ray incident/exit surface of the light emitting/receiving layer, the characteristics of the infrared light device can be improved (FIG. 12). For example, in the case of an LED, the light emitted from the light emitting layer on the side opposite to the entrance/exit surface can be redirected toward the entrance/exit surface by reflection, so that the light emission intensity can be improved. For example, in the case of a PD, the light that has passed through the light-receiving layer among the incident light can be directed to the light-receiving layer again by reflection, so that the light-receiving sensitivity can be improved.

At this time, the reflective photonic crystal may be formed in any shape, for example, it may be arranged to form a paraboloid in order to improve the directivity of the LED (FIG. 13).

(Example)
FIG. 14 shows the dependence of the refractive index of the InSb layer on the n-type impurity concentration. Doping was performed using Sn. As shown in FIG. 14, as the n-type impurity concentration, that is, the n-type carrier concentration increases, the refractive index decreases significantly. This tendency becomes more noticeable as the wavelength goes from short to long. In the example of FIG. 14, four infrared wavelengths are shown. On the other hand, no concentration dependence of the refractive index was observed with respect to the p-type impurity concentration. A similar tendency was also observed for materials made of InSb mixed with Al, Ga, and As. Here, the leftmost point in FIG. 14 where the n-type impurity concentration is 0 indicates the value of undoped i-InSb.

Claims (13)

It has a periodic structure composed of multiple regions with different impurity concentrations,
A photonic crystal whose constituent material is Al _x Ga _y In _1-x-y As _z Sb _1-z (0≦x+y≦0.5, 0≦z≦1.0). The photonic crystal according to claim 1, wherein the periodic structure has periodicity in three different directions that are not on the same plane. The photonic according to claim 1 or 2, wherein the constituent material is Al _x Ga _y In _1-x-y As _z Sb _1-z (0≦x+y≦0.5, 0≦z≦0.5). crystal. The periodic structure consists of a low refractive index region and a high refractive index region,
The low refractive index region includes an N-type semiconductor region having an impurity concentration of 1.0×10 ¹⁸ /cm ³ or more,
3. The high refractive index region includes at least one of a P-type semiconductor region, an intrinsic semiconductor region, and an N-type semiconductor region having a lower impurity concentration than the N-type semiconductor region of the low refractive index region. photonic crystal. 5. The photonic crystal according to claim 4, wherein the low refractive index region includes an N-type semiconductor region having an impurity concentration of 3.0×10 ¹⁸ /cm ³ or more. 5. The photoreceptor according to claim 4, wherein the high refractive index region includes at least one of a P-type semiconductor region, an intrinsic semiconductor region, and an N-type semiconductor region having an impurity concentration of less than ^3.0 ×10 ¹⁷ /cm 3 . Nick crystal. The photonic crystal according to claim 1 or 2, wherein the photonic crystal is provided on a substrate and has a periodic structure having periodicity in a plane direction of one main surface of the substrate. A substrate and
a light receiving and emitting layer that receives or emits infrared light;
An infrared light device comprising the photonic crystal according to claim 1 or 2. 9. The infrared light device according to claim 8, wherein the bandgap of the constituent material of the photonic crystal is larger than the bandgap of the light emitting/receiving layer. 9. The infrared light device according to claim 8, wherein the infrared light device has an input/output surface that emits or receives infrared rays, and the photonic crystal is formed on the side of the input/output surface with respect to the light receiving/emitting layer. The infrared light device according to claim 10, wherein the photonic crystal is formed on the input and output surfaces. The infrared light device according to claim 8, wherein a distance between the photonic crystal and the light emitting/receiving layer is within one wavelength of light corresponding to a band gap of the light emitting/receiving layer. 9. The infrared light device according to claim 8, wherein the infrared light device has an input/output surface that emits or receives infrared rays, and the photonic crystal is formed on the opposite side of the input/output surface with respect to the light receiving/emitting layer. .

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