JP6895348B2 - Infrared light emitting element - Google Patents

Description

The present invention relates to an infrared light emitting device.

In recent years, an infrared light emitting device having a wavelength region of mid-infrared, particularly a wavelength of about 2.0 μm to 12 μm, has attracted attention. Since this wavelength region is a wavelength region in which _{light absorption by gas molecules such as CO 2} and hydrocarbons can be seen, the absorption amount is detected by combining an LED light source, an infrared sensor, and an optical filter that transmits only the desired wavelength band. Therefore, it is expected to be applied as a low power consumption non-dispersive gas sensor that measures the concentration of gas molecules.
Patent Document 1 describes an infrared light emitting device having a substrate and a semiconductor laminated portion formed on one surface of the substrate, and the back surface (opposite surface of one surface) of the substrate is a light extraction surface. This semiconductor laminated portion has a first conductive type semiconductor layer, a light emitting layer, and a second conductive type semiconductor layer in this order from one surface side of the substrate, and has a mesa part made of a material containing In and Sb. Further, a GaAs substrate is exemplified as the substrate. Then, a technique for improving the luminous efficiency (emission intensity per unit area) of the infrared light emitting element is described.

Japanese Unexamined Patent Publication No. 2016-149392

Infrared light emitting devices having the back surface of the substrate as the light extraction surface are required to improve the light extraction efficiency, but at present, no useful technique for improving the light extraction efficiency has been proposed.
An object of the present invention is to improve the light extraction efficiency of an infrared light emitting element having the back surface of the substrate as the light extraction surface.

In order to solve the above problems, the infrared light emitting device of the first aspect of the present invention has the following configurations (1) to (4).
(1) A GaAs substrate and a semiconductor laminated portion formed on one surface of the GaAs substrate, which has a first conductive semiconductor layer, a light emitting layer, and a second conductive semiconductor layer in this order from the one surface side. The one conductive semiconductor layer is formed of a material containing In and Sb, has a first mesa portion protruding from one surface and a second mesa portion protruding from the first mesa portion, and has a first mesa portion and a second mesa portion. A semiconductor laminated portion whose boundary with the light emitting layer is closer to the GaAs substrate side than the light emitting layer is provided.
(2) In a cross section perpendicular to one surface of the GaAs substrate, the angle α formed by the reference line segment S1 defined below and the one surface line forming one surface of the GaAs substrate is 32.2 ° <α ≦ 90 °. Meet. The reference line segment S1 connects the center point A of the boundary line between the light emitting layer and the second conductive semiconductor layer and the common point B between the first side surface line and the one surface line forming the side surface of the first mesa portion. It is a line segment that does not intersect with the second side surface line that forms the side surface of the second mesa portion.
(3) In the cross section perpendicular to one surface of the GaAs substrate, the angle β formed by the reference side surface line and the one surface line satisfies 32.2 ° <β ≦ 90 °. The reference side line is a straight line including the second side line and does not intersect with the first side line.
(4) The back surface of the GaAs substrate, which is the opposite surface of one surface, is the light extraction surface.

The infrared light emitting device of the second aspect of the present invention has the above configurations (1), (3) and (4) and the following configurations (5).
(5) In the cross section perpendicular to one surface of the GaAs substrate, the angle γ formed by the reference straight line S2 defined below and the one surface line forming one surface of the GaAs substrate is 32.2 ° <γ ≦ 90 °. Fulfill. The reference straight line S2 is a straight line including a line segment connecting the center point A of the boundary line between the light emitting layer and the second conductive semiconductor layer and the boundary point C between the first mesa portion and the second mesa portion. It is a straight line that does not intersect the first side surface line that forms the side surface of the first mesa part.

According to the infrared light emitting device of the present invention, it is expected that the light extraction efficiency can be improved by specifying the angle α or the angle γ and the angle β in the cross section perpendicular to one surface of the GaAs substrate.

It is a figure which shows the cross section perpendicular to one surface of the GaAs substrate of the infrared light emitting element of the 1st aspect, and explains the reference line segment S1 and the angle α. It is a figure which shows the cross section perpendicular to one surface of the GaAs substrate of the infrared light emitting element of the 1st aspect and 2nd aspect, and explains the reference side surface line L1 and the angle β. From the incident angle θ21 at which the refraction angle θ3 of the light incident on the air from GaAs is 90 ° and the InSb for that purpose, which shows a cross section perpendicular to one surface of the GaAs substrate of the infrared light emitting element of the first aspect and the second aspect. It is a figure explaining the incident angle θ1 of the light incident on GaAs. It is a figure which shows the cross section perpendicular to one surface of the GaAs substrate of the infrared light emitting element of the 1st aspect and 2nd aspect, and explains the preferable range of an angle β. It is a figure which shows the cross section perpendicular to one surface of the GaAs substrate of the infrared light emitting element of the 2nd aspect, and explains the reference line S2 and the angle γ. FIG. 3A is a plan view showing an infrared light emitting device according to an embodiment of the present invention, and FIG. 3B is a cross-sectional view taken along the line AA. It is a partially enlarged view of FIG. 6 (b). It is sectional drawing explaining the method of forming the semiconductor laminated part which comprises the infrared light emitting element of one Embodiment. It is sectional drawing which shows the infrared light emitting device which includes the infrared light emitting element of one Embodiment.

[Detailed description of the first aspect and the second aspect of the present invention]
The infrared light emitting device of the first aspect of the present invention includes a GaAs substrate, the light extraction surface is the back surface of the GaAs substrate (the opposite surface of one surface on which the semiconductor laminated portion is formed), and the semiconductor laminated portion is the first mesa portion. An infrared light emitting device having a second mesa portion and a first conductive semiconductor layer made of a material containing In and Sb, characterized by having the above configurations (2) and (3).
When the wavelength is 4.0 μm, the refractive index n1 of InSb is 3.9 and the refractive index n2 of GaAs is 3.3. Therefore, according to Snell's law (n1 × sinθ1 = n2 × sinθ2), InSb is changed to GaAs. The incident angle θ1 at which the refraction angle θ2 of the incident light is 90 ° is θ1 = sin ^-1 (n2 / n1) = 57.79577 ° ≈57.8 °.

That is, when the first conductive semiconductor layer 31 of the infrared light emitting element is the InSb layer, as shown in FIG. 1, the second conductive semiconductor of the light emitting layer 33 has a cross section perpendicular to one surface of the GaAs substrate 2. Light having a wavelength of 4.0 μm from the center point A of the boundary line with the layer 35 toward the common point B between the first side surface line L301 forming the side surface of the first mesa portion 301 and the one side line L21 forming one surface of the GaAs substrate 2. When the incident angle θ1 is 57.8 °, the refraction angle θ2 becomes 90 °. Therefore, if the angle α (90 ° −θ1) formed by the reference line segment S1 connecting the points A and B and the one-sided line L21 is larger than 32.2 ° (for example, if it is 32.3 ° or more), this light Enters the GaAs substrate 2 without total internal reflection. Since the difference in refractive index between the semiconductor layers forming the semiconductor laminated portion is generally small, it can be considered that the light incident on the first conductive semiconductor layer 31 from the light emitting layer 33 travels substantially straight.

That is, by having the above configuration (2), when the first conductive semiconductor layer 31 is an InSb layer, ideally, all the light having a wavelength of 4.0 μm from the center point A toward the GaAs substrate 2 is emitted from the GaAs substrate. Can be incident on. Therefore, the infrared light emitting device of the first aspect can be expected to improve the light extraction efficiency by having the above configuration (2).
When the first conductive semiconductor layer 31 of the infrared light emitting element is an InSb layer, as shown in FIG. 2, the second mesa portion 302 of the light emitting layer 33 has a cross section perpendicular to one surface of the GaAs substrate. If the angle β formed by the straight line L1 including the second side surface line L302 forming the side surface and the one side line L21 is 32.2 ° or less, the light directed to the GaAs substrate 2 along the straight line L1 is for the same reason as described above. , Enters the GaAs substrate 2 without total reflection.

On the other hand, as shown by the alternate long and short dash line in FIG. 2, when the inclination of the side surface of the second mesa portion is smaller than the inclination of the solid line (that is, the angle β is smaller than 32.2 °), the second side surface line L302 The light directed to the GaAs substrate 2 along the straight line L10 including the above is totally reflected at the interface. Therefore, in the case of an infrared light emitting device having a second side line L302 indicated by a two-dot chain line, the light E directed to the GaAs substrate 2 between the straight line L10 and the straight line L1 having an angle β of 32.2 ° is the GaAs substrate. Does not fit in 2.
That is, by satisfying β> 32.2 °, when the first conductive semiconductor layer 31 is an InSb layer, the wavelength directed from the widthwise end D of the light emitting layer along the straight line L1 including the second side surface line L302. Ideally, all 4.0 μm light can be incident on the GaAs substrate.
Therefore, the infrared light emitting device of the first aspect can be expected to improve the light extraction efficiency by having the above configuration (3).

Further, the smaller the inclination of the side surface of the second mesa portion, the larger the amount of light that does not enter the GaAs substrate 2 from both ends in the width direction of the light emitting layer, and the wider the width of the infrared light emitting element. Therefore, β ≦ 32.2 ° is not preferable in terms of miniaturization of the infrared light emitting element.
On the other hand, considering the interface between the GaAs substrate and air, the refractive index n3 of air is 1.0 and the refractive index n2 of GaAs is 3.3 when the wavelength is 4.0 μm. Therefore, as shown in FIG. 3, assuming that the incident angle of light incident on the air from the GaAs substrate is θ21 and the refraction angle is θ3, the refraction angle θ3 is 90 according to Snell's law (n2 × sin θ21 = n3 × sin θ3). The incident angle θ21 at ° is θ21 = sin ^-1 (n3 / n2) = 17.6397 ° ≈ 17.6.

That is, if the incident angle θ21 is larger than 17.6 °, the light entering the GaAs substrate 2 can be taken out into the air from the back surface 22.
Since the incident angle θ21 and the refraction angle θ2 are the same, the incident angle θ1 at which the refraction angle θ2 is 17.6 is θ1 = sin ^-1 (n2 / n1) = 14.824 ° ≈ 14.8 °. If θ1 is less than 14.8 ° (that is, the marginal angle δ of θ1 is larger than 75.2 °), light having a wavelength of 4.0 μm entering the GaAs substrate 2 from the InSb layer 31 is introduced into the air from the back surface 22. Can be taken out.
Therefore, if the angle α corresponding to the margin angle δ is larger than 75.2 ° (for example, if it is 75.3 ° or more), when the first conductive semiconductor layer 31 is an InSb layer, the center point A to the point B Ideally, all the light having a wavelength of 4.0 μm that has passed through the GaAs substrate 2 and entered the GaAs substrate 2 can be taken out into the air from the back surface of the GaAs substrate 2, which is preferable.

Further, with respect to the light having a wavelength of 4.0 μm from the widthwise end D of the light emitting layer 33 toward the GaAs substrate 2, the light having a marginal angle δ of the incident angle θ1 larger than 75.2 ° is emitted from the InSb layer 31 to the GaAs substrate 2. It can be taken out into the air from the back surface 22. Then, as shown in FIG. 4, when the second side surface line L302 is β = 90 ° indicated by the alternate long and short dash line for the angle β corresponding to the margin angle δ, the second side surface line L302 is indicated by the solid line β. The amount of light taken out into the air is smaller by the area indicated by the triangle F than in the case of = 75.2 °. That is, when the angle β is larger than 75.2 °, the amount of the light taken out into the air is small, so that the angle β is preferably 75.2 ° or less.

The infrared light emitting device of the second aspect of the present invention includes a GaAs substrate, the light extraction surface is the back surface of the GaAs substrate (the opposite surface of one surface on which the semiconductor laminated portion is formed), and the semiconductor laminated portion is the first mesa portion. An infrared light emitting device having a second mesa portion and a first conductive semiconductor layer made of a material containing In and Sb, characterized by having the above configurations (3) and (5).
When the first conductive semiconductor layer 31 of the infrared light emitting element is an InSb layer, as shown in FIG. 5, the second conductive semiconductor layer 35 of the light emitting layer 33 has a cross section perpendicular to one surface of the GaAs substrate 2. Light having a wavelength of 4.0 μm from the center point A of the boundary line with and through the boundary point C between the first mesa portion 301 and the second mesa portion 302 toward the GaAs substrate 2 has an incident angle θ1 of 57.8 °. At this time, the refraction angle θ2 becomes 90 °. Therefore, if the angle γ (90 ° −θ1) formed by the reference straight line S2 and the one-sided line L21 is larger than 32.2 ° (for example, 32.3 ° or more), this light is not totally reflected and is GaAs. Enter the substrate 2.

That is, by having the above configuration (5), when the first conductive semiconductor layer 31 is an InSb layer, light having a wavelength of 4.0 μm from the center point A to the GaAs substrate 2 through the point C is ideal. Can all be incident on a GaAs substrate. Therefore, the infrared light emitting device of the second aspect can be expected to improve the light extraction efficiency by having the above configuration (5).
The reason why the light extraction efficiency can be expected to be improved by having the infrared light emitting element of the second aspect having the above configuration (3) is the same as the reason explained in the infrared light emitting element of the first aspect.
Further, regarding the consideration at the interface between the GaAs substrate and the air, the angle γ corresponds to the margin angle δ described in the infrared light emitting device of the first aspect.

Therefore, even in the case of the infrared light emitting device of the second aspect, if the angle γ corresponding to the residual angle δ is larger than 75.2 ° (for example, if it is 75.3 ° or more), the first conductive semiconductor layer 31 is InSb. In the case of a layer, it is preferable because all the light having a wavelength of 4.0 μm that has entered the GaAs substrate 2 from the center point A through the point C can be ideally taken out into the air from the back surface of the GaAs substrate 2.
Further, the angle β is preferably 75.2 ° or less for the same reason as described in the first correspondence.
The first aspect and the second aspect of the present invention have been described above by taking the case where the first conductive semiconductor layer is InSb as an example, but the semiconductor layer containing In and Sb has a refractive index close to that of InSb. Therefore, the same effect as described above can be expected even when the first conductive semiconductor layer is made of a material other than InSb (for example, InAsSb or AlInSb).

Hereinafter, the configurations of the infrared light emitting device according to the first aspect and the second aspect of the present invention will be described.
<Semiconductor laminate>
The semiconductor laminated portion is formed on one surface of a GaAs substrate, and has a first conductive semiconductor layer, a light emitting layer, and a second conductive semiconductor layer in this order from the one surface side, and the first conductive semiconductor layer is In and It is made of a material containing Sb. Further, it has a first mesa portion protruding from one surface of the GaAs substrate and a second mesa portion protruding from the first mesa portion, and the boundary between the first mesa portion and the second mesa portion is closer to the GaAs substrate than the light emitting layer. Exists in. Here, the first conductive type may be any of n type, i type and p type. Further, the second conductive type may be any of n type, i type and p type. It is preferable that the first conductive type semiconductor layer and the second conductive type semiconductor layer have different conductive types.

The semiconductor laminated portion may include a layer other than the first conductive type semiconductor layer, the light emitting layer, and the second conductive type semiconductor layer. Specifically, another layer may be provided between the first conductive semiconductor layer and the light emitting layer. For example, when the first conductive type semiconductor layer is an i-type buffer layer, an n-type semiconductor layer may be provided between the buffer layer and the light emitting layer. Further, another layer may be provided between the light emitting layer and the second conductive semiconductor layer.
In the semiconductor laminate, for example, an n-type semiconductor layer (p-type semiconductor layer), a light emitting layer, and a p-type semiconductor layer (n-type semiconductor layer) are formed on a semi-insulating GaAs substrate in this order, and the laminate is formed. It is formed by performing two-step processing using a wet etching or dry etching method. Examples of the film forming method include a molecular beam epitaxy method (MBE) and a metalorganic vapor phase growth method (MOCVD).

The first conductive semiconductor layer is a layer made of a material containing In and Sb. The light emitting layer and the second conductive semiconductor layer are also preferably layers made of a material containing In and Sb. Examples of the material containing In and Sb include InSb, InGaSb, AlGaSb, InAs, InAlAs, InAlSb and InAsSb. When the light emitting layer is made of these materials, it is possible to efficiently generate the above-mentioned infrared rays having a wavelength of 4.0 μm.

<Sealing part>
It is preferable that the infrared light emitting device of the first aspect and the second aspect of the present invention includes a sealing portion that exposes at least a part of the back surface and seals the semiconductor laminated portion. Thereby, the semiconductor laminated portion can be protected from the external environment. As the material of the sealing portion, for example, a resin molding material such as an epoxy resin or a phenol resin can be used. At that time, a resin molding material containing a filler such as _{SiO 2} or Al ₂ O _{3 may be used.} Further, a stress relaxation layer (buffer layer) made of polyimide, polyamide, silicone resin or the like may be provided between the semiconductor laminated portion and the sealing portion.

<Metal layer>
The infrared light emitting device of the first aspect and the second aspect of the present invention preferably includes a metal layer. This metal layer has a first portion that contacts the first conductive semiconductor layer of the first mesa portion and a second portion that is independent of the first portion and contacts the second conductive semiconductor layer of the second mesa portion. And have. The first portion and the second portion of the metal layer are usually formed in the semiconductor laminated portion via an insulating layer, and the first conductive type semiconductor layer and the second conductive type semiconductor layer are formed through an opening provided in the insulating layer. Contact. Further, the metal layer is divided into a first metal layer (including the first portion) formed on the first mesa side and a second metal layer (including the second portion) formed on the second mesa side. , The first metal layer and the second metal layer can each have a third portion formed on one surface of a GaAs substrate.

The metal layer is used as an electrode for electrical connection between the first conductive semiconductor layer and the second conductive semiconductor layer via an external power source. Further, when a plurality of semiconductor laminated portions are provided on a GaAs substrate, they are used as wiring for connecting these in series. Further, since the metal layer is formed on one surface of the GaAs substrate (having a third portion), the reflectance of the light generated in the light emitting layer on one surface of the GaAs substrate is increased, and the light generated in the light emitting layer is increased. Can be efficiently extracted from the light extraction surface (the back surface of the GaAs substrate).
The metal layer preferably has a laminated structure in which, for example, an adhesion layer, a barrier layer, and a low resistance layer are laminated in this order from the semiconductor laminated portion and the GaAs substrate side.

As the adhesion layer of the laminated structure, a material having good adhesion to the insulating layer such as Ti or Cr and having low contact resistance with the n-type semiconductor layer and the p-type semiconductor layer is used. The barrier layer is provided to suppress mutual diffusion between the metal layer material and the semiconductor layer, and for example, Pt can be used. The low resistance layer is preferably low resistance in order not to cause voltage loss due to an unnecessary potential difference in connection with the outside via a metal layer or connection between a plurality of semiconductor laminates. For example, Au is used. Can be done.
Further, when the metal layer has a laminated structure, the adhesion layer has a role of reflecting the light generated in the light emitting layer by the third portion of the metal layer, so that it is desirable that the light absorption loss is small.

[Embodiment]
Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the embodiments shown below. In the embodiments shown below, technically preferable limitations are made for carrying out the present invention, but these limitations are not essential requirements of the present invention.
As shown in FIG. 6, the infrared light emitting element 1 of this embodiment includes a GaAs substrate 2, a semiconductor laminated portion 3, an insulating layer 4, a metal layer 5, and a back surface insulating film 6.
One side 21 of the GaAs substrate 2 is a [100] side, and the back side 22 is a [-100] side. The semiconductor laminated portion 3 is formed on one surface 21 of the GaAs substrate 2.

The semiconductor laminated portion 3 has a two-stage mesa structure including a first mesa portion 301 protruding from one surface 21 of the GaAs substrate 2 and a second mesa portion 302 protruding from the first mesa portion 301.
As shown in FIG. 7, the semiconductor laminated portion 3 includes a Sn-doped InSb layer (corresponding to an n-type semiconductor layer and a first conductive semiconductor layer) 31 and a Sn-doped AlInSb layer (n-type barrier layer) from the GaAs substrate 2 side. 32, non-doped AlInSb layer (corresponding to light emitting layer) 33, Zn-doped AlInSb layer (p-type barrier layer) 34, and Zn-doped AlInSb layer (corresponding to p-type semiconductor layer, second conductive semiconductor layer) 35 in this order. Have. As shown in FIGS. 6 and 7, the boundary between the first mesa portion 301 and the second mesa portion 302 exists in the Sn-doped InSb layer 31.

As shown in FIG. 8, the semiconductor laminated portion 3 is a semiconductor composed of an n-type semiconductor layer 31, an n-type barrier layer 32, a light emitting layer 33, a p-type barrier layer 34, and a p-type semiconductor layer 45 on a GaAs substrate 2. After forming the laminate 30, it is formed by performing mesa etching along the alternate long and short dash line and then mesa etching along the alternate long and short dash line.
The insulating layer 4 is formed around the upper surfaces and side surfaces of the first mesa portion 301 and the second mesa portion 302 of the semiconductor laminated portion 3 and the first mesa portion 301 on one surface 21 of the GaAs substrate 2. The insulating layer 4 has a first opening 41 on the n-type semiconductor layer 31 of the first mesa portion 301. The second opening 42 is provided on the p-type semiconductor layer 35 of the second mesa portion 302.

The metal layer 5 is divided into a first metal layer 510 formed on the first mesa portion 301 side and a second metal layer 520 formed on the second mesa portion 302 side. The first metal layer 510 includes a portion (first portion) 511 that closes the first opening 41 and contacts the n-type semiconductor layer 31 of the first mesa portion 301, a portion 512 formed on the insulating layer 4, and GaAs. It is composed of a portion (third portion, electrode) 513 formed on one surface 21 of the substrate 2. The second metal layer 520 includes a portion (second portion) 521 that closes the second opening 42 and contacts the p-type semiconductor layer 35 of the second mesa portion 302, and a portion 522 formed on the insulating layer 4. It is composed of a portion (third portion, electrode) 523 formed on one surface 21 of the GaAs substrate 2.

FIG. 7 is a partially enlarged view of the AA cross section of FIG. 6A, showing one of the cross sections perpendicular to one surface 21 of the GaAs substrate 2. Then, as shown in FIG. 7, the infrared light emitting element 1 has common points B1 and B2 between the first side surface line L301 and the one side line L21 forming the side surface of the first mesa portion 301.
The line segment connecting the common point B1 and the center point A of the boundary line between the p-type barrier layer (second conductive semiconductor layer) 34 of the light emitting layer 33 is the second side surface forming the side surface of the second mesa portion 302. Since it does not intersect the line L302, it is a reference line segment S1. The angle α formed by the reference line segment S1 and the one-sided line L21 satisfies 32.2 ° <α ≦ 90 °. The line segment LS connecting the common point B2 and the center point A is not the reference line segment S1 because it intersects with the second side surface line L302 forming the side surface of the second mesa portion 302.

Further, at both ends in the width direction of the cross section shown in FIG. 7, the straight line L1 including each second side surface line L302 does not intersect with the first side surface line, and thus both are reference side surface lines. Then, the infrared light emitting element 1 satisfies the angle β formed by the straight line L1 and the one-sided line L21, which is the reference side surface line, at 32.2 ° <β ≦ 75.2 ° at both ends in the width direction of the cross section shown in FIG. ing.
Further, at both ends in the width direction of the cross section shown in FIG. 7, each straight line including the line segment connecting the center point A and the boundary point C between the first mesa portion 301 and the second mesa portion 302 is the first mesa. Since it does not intersect the first side surface line L301 forming the side surface of the portion 301, both are reference straight lines S2. Further, in this example, the reference straight line S2 on the left side of FIG. 7 includes the reference line segment S1. That is, the angle γ formed by the reference straight line S2 on the left side of FIG. 7 and the one-sided line L21 is the same as the angle α. The infrared light emitting element 1 satisfies 32.2 ° <γ ≦ 90 ° at both ends in the width direction of the cross section shown in FIG. 7.

As described above, since the infrared light emitting element 1 satisfies α> 32.2 ° in the cross section shown in FIG. 7, ideally, light having a wavelength of 4.0 μm from the center point A toward the GaAs substrate 2 is emitted. All can be incident on the GaAs substrate 2. Further, by satisfying γ> 32.2 °, all the light having a wavelength of 4.0 μm from the center point A to the GaAs substrate 2 through the point C can ideally be incident on the GaAs substrate. .. Further, when the angle β satisfies 32.2 ° <β ≦ 75.2 °, the wavelength 4. Ideally, all 0 μm of light can be incident on the GaAs substrate 2, and the amount of this light taken out from the back surface 22 of the GaAs substrate 2 into the air can be increased.

Therefore, the infrared light emitting device 1 of the embodiment has a high light extraction efficiency of a wavelength of 4.0 μm.
Although the angles α, β, and γ in one cross section (AA cross section of FIG. 6A) perpendicular to one surface 21 of the GaAs substrate 2 of the infrared light emitting element 1 are described here, GaAs. It is preferable that 32.2 ° <α, β, γ ≦ 90 ° is satisfied in two or more cross sections perpendicular to one surface 21 of the substrate 2, and all the cross sections perpendicular to one surface 21 of the GaAs substrate 2. It is more preferable that the cross section satisfies 32.2 ° <α, β, γ ≦ 90 °.

<Infrared light emitting device>
The infrared light emitting device 10 shown in FIG. 9 can be manufactured by using the infrared light emitting element 1 of the first embodiment. The infrared light emitting device 10 includes an infrared light emitting element 1, lead terminals 71 and 72, thin metal wires 82 and 82, and a sealing portion 9.
The lead terminals 71 and 72 are arranged around the infrared light emitting element 1. The thin metal wire 81 connects the third portion (first electrode) 513 of the first metal layer 510 of the infrared light emitting element 1 and the lead terminal 71. The thin metal wire 82 connects the third portion (second electrode) 523 of the second metal layer 520 of the infrared light emitting element 1 and the lead terminal 72. The sealing portion 9 is arranged in a portion of the back surface insulating film 6 of the infrared light emitting element 1 excluding the surface opposite to the GaAs substrate 2, and seals between the infrared light emitting element 1 and the lead terminals 71 and 72. There is. That is, the semiconductor laminated portion 3 of the infrared light emitting element 1 is sealed.

That is, the infrared light emitting device 10 is an example of an infrared light emitting element 1 including a sealing portion 9 that seals the semiconductor laminated portion 3.
In the infrared light emitting device 1 of the above embodiment, the first metal layer 510, the second metal layer 520, and the metal layer 530 have portions 513,523,533 that come into contact with one surface 21 of the GaAs substrate 2. An insulating film may be interposed between one surface 21 of the GaAs substrate 2 and these portions.

1 Infrared light emitting element 2 GaAs substrate 21 One side of GaAs substrate 211 Area where one surface of semiconductor laminate is not formed 22 Back surface of GaAs substrate 3 Semiconductor laminate 30 Semiconductor laminate 31 n-type semiconductor layer 32 n-type barrier layer 33 Light emitting layer 34 p-type barrier layer 35 p-type semiconductor layer 301 First mesa part 3011 Upper surface not covered by the second mesa part of the first mesa part 302 Second mesa part 4 Insulation layer 5 Metal layer 510 First metal layer 511 n-type Part in contact with the semiconductor layer (first part)
512 Part formed on the insulating layer 513 Part formed on one surface of the GaAs substrate (third part, electrode)
520 Second metal layer 521 Part in contact with p-type semiconductor layer (second part)
522 Part formed on the insulating layer 523 Part formed on one surface of the GaAs substrate (third part, electrode)
71, 72 Lead terminal 81, 82 Fine metal wire 9 Sealing part 10 Infrared light emitting device S1 Reference line segment S2 Reference straight line L1 Reference side line (straight line including the second side line)
L21 one side line

Claims (8)

With a GaAs substrate
A semiconductor laminated portion formed on one surface of the GaAs substrate, which has a first conductive semiconductor layer, a light emitting layer, and a second conductive semiconductor layer in this order from the one surface side, and the first conductive semiconductor. The layer and the light emitting layer are made of any one of InSb, InAsSb, and AlInSb, and have a first mesa portion protruding from one surface and a second mesa portion protruding from the first mesa portion. A semiconductor laminated portion in which the boundary between the first mesa portion and the second mesa portion exists on the GaAs substrate side of the light emitting layer.
With
In a cross section perpendicular to the one surface
The center point A of the boundary line between the light emitting layer and the second conductive semiconductor layer and the common point B between the first side surface line forming the side surface of the first mesa portion and the one surface line forming the one surface are connected. A reference line segment that is a line segment and does not intersect the second side surface line forming the side surface of the second mesa portion and the angle α formed by the one surface line satisfy 32.2 ° <α ≦ 90 °.
The angle β formed by the reference side surface line including the second side surface line and not intersecting with the first side surface line and the one surface line satisfies 32.2 ° <β ≦ 90 °.
Ri backside light extraction surface der of the GaAs substrate which is opposite side of the one surface, an infrared light-emitting element you emit infrared wavelengths including at least 4.0 .mu.m. The infrared light emitting device according to claim 1, wherein the angle α satisfies 75.2 ° <α ≦ 90 °. The infrared light emitting device according to claim 1 or 2, wherein the angle β satisfies 32.2 ° <β ≦ 75.2 °. With a GaAs substrate
A semiconductor laminated portion formed on one surface of the GaAs substrate, which has a first conductive semiconductor layer, a light emitting layer, and a second conductive semiconductor layer in this order from the one surface side, and the first conductive semiconductor. The layer and the light emitting layer are made of any one of InSb, InAsSb, and AlInSb, and have a first mesa portion protruding from one surface and a second mesa portion protruding from the first mesa portion. A semiconductor laminated portion in which the boundary between the first mesa portion and the second mesa portion exists on the GaAs substrate side of the light emitting layer.
With
In a cross section perpendicular to the one surface
A straight line including a line segment connecting the center point A of the boundary line between the light emitting layer and the second conductive semiconductor layer and the boundary point C between the first mesa portion and the second mesa portion. The angle γ formed by the reference straight line that does not intersect the first side surface line forming the side surface of the one mesa portion and the one surface line forming the one surface satisfies 32.2 ° <γ ≦ 90 °.
The angle β formed by the reference side surface line which is a straight line including the second side surface line forming the side surface of the second mesa portion and does not intersect with the first side surface line and the one surface line is 32.2 ° <β ≦. Satisfy 90 °,
Ri backside light extraction surface der of the GaAs substrate which is opposite side of the one surface, an infrared light-emitting element you emit infrared wavelengths including at least 4.0 .mu.m. The infrared light emitting device according to claim 4, wherein the angle γ satisfies 75.2 ° <γ ≦ 90 °. The infrared light emitting device according to claim 4 or 5, wherein the angle β satisfies 32.2 ° <β ≦ 75.2 °. The infrared light emitting device according to any one of claims 1 to 6, wherein the first conductive semiconductor layer is an InSb layer. The infrared light emitting device according to any one of claims 1 to 7, further comprising a sealing portion for exposing at least a part of the back surface and sealing the semiconductor laminated portion.

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