JP2022129220A - Light receiving/emitting element, light emitting/receiving element module, and sensor device - Google Patents

Abstract

To reduce the occurrence of optical noise due to leaked light.SOLUTION: A light emitting/receiving element 1 includes a semiconductor substrate 7, a light emitting portion 3, a light receiving portion 4, and a semiconductor layer 8. The semiconductor substrate 7 is made of a semiconductor material and has a first surface 7a and a second surface 7b opposite to the first surface 7a. The light emitting portion 3 and the light receiving portion 4 are located on the first surface 7a of the semiconductor substrate 7. The semiconductor layer 8 is located on the second surface 7b of the semiconductor substrate 7. As a constituent material of the semiconductor layer 8 located on the second surface 7b, a semiconductor material having a higher refractive index than that of the constituent material of the semiconductor substrate 7 is used.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present disclosure relates to a light emitting/receiving element, a light emitting/receiving element module, and a sensor device.

A conventional light emitting/receiving element module and a sensor device using the module are equipped with a light emitting element and a light receiving element, and are configured such that light emitted from the light emitting element is reflected by an object to be irradiated and the reflected light is received by the light receiving element. It is The light emitting/receiving element module described in Patent Document 1 includes a light emitting element and a light receiving element on one surface of a semiconductor substrate.

WO2016/175246

Further miniaturization is desired for such a light emitting/receiving element module by, for example, shortening the distance between the light emitting element and the light receiving element. However, due to the miniaturization, part of the leaked light from the light-emitting element may pass through the semiconductor substrate, be reflected by the metal layer on the back surface of the substrate, and be received by the light-receiving element.

An object of the present disclosure is to provide a light emitting/receiving element, a light emitting/receiving element module, and a sensor device capable of reducing the occurrence of optical noise due to leaked light.

A light emitting/receiving device of the present disclosure includes: a semiconductor substrate having a first surface and a second surface opposite to the first surface;
a light-emitting portion and a light-receiving portion located on the first surface;
a semiconductor layer located on the second surface;
The refractive index of the constituent material of the semiconductor layer is higher than the refractive index of the constituent material of the semiconductor substrate.

The light emitting/receiving element module of the present disclosure includes the light emitting/receiving element described above,
a wiring board on which the light emitting/receiving element is mounted;
and an optical member including a first lens that transmits light emitted from the light emitting unit and a second lens that transmits light incident on the light receiving unit.

The sensor device of the present disclosure includes the light receiving and emitting element module described above,
a control circuit that is electrically connected to the light emitting/receiving element module, controls emitted light emitted from the light emitting unit, and detects an amount of light received by the light receiving unit.

According to the light emitting/receiving element and the light emitting/receiving element module of the present disclosure, it is possible to reduce the occurrence of optical noise due to leaked light.

According to the sensor device of the present disclosure, sensing accuracy can be improved.

1 is a schematic cross-sectional view showing a light emitting/receiving element that is an embodiment of the present disclosure; FIG. (a) is an enlarged cross-sectional view showing a light emitting portion of a light emitting/receiving element, and (b) is an enlarged cross-sectional view showing a light receiving portion of the light emitting/receiving element. FIG. 4 is a schematic cross-sectional view showing a light emitting/receiving element that is another embodiment of the present disclosure; BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic which shows the light emitting/receiving element module which is embodiment of this indication, (a) shows a top view, (b) shows sectional drawing. 1 is a schematic diagram showing a sensor device that is an embodiment of the present disclosure; FIG.

FIG. 1 is a schematic cross-sectional view showing a light emitting/receiving element that is an embodiment of the present disclosure. The light emitting/receiving element 1 includes a semiconductor substrate 7 , a light emitting section 3 , a light receiving section 4 and a semiconductor layer 8 . The semiconductor substrate 7 is made of a semiconductor material and is a plate-like member having a first surface 7a and a second surface 7b opposite to the first surface 7a. A light-emitting portion 3 and a light-receiving portion 4 are positioned on a first surface 7 a of the semiconductor substrate 7 . A semiconductor layer 8 is located on the second surface 7 b of the semiconductor substrate 7 .

The light-emitting portion 3 and the light-receiving portion 4 share one semiconductor substrate 7 as a base material and are formed on the same first surface 7a of the semiconductor substrate 7 . This makes it possible to arrange the light-emitting part 3 and the light-receiving part 4 in close proximity to each other, compared to a structure in which the light-emitting element and the light-receiving element are mounted as individual elements on a wiring board. Miniaturization and improved sensing performance are possible. Further, although the light emitting/receiving element 1 of the present embodiment includes one light emitting section 3 and one light receiving section 4 , it may include a plurality of light emitting sections 3 and a plurality of light receiving sections 4 .

The semiconductor substrate 7 is made of a semiconductor material of one conductivity type. The semiconductor substrate 7 of this embodiment is made of a semiconductor material of one conductivity type. The semiconductor substrate 7 of this embodiment uses, for example, an n-type Si (silicon) substrate, and has a thickness of, for example, 300 to 500 μm. That is, the semiconductor substrate 7 is made of Si, and is formed by doping an Si substrate with an n-type impurity. As the n-type impurity for the Si substrate, for example, P (phosphorus), N (nitrogen), As (arsenic), Sb (antimony), Bi (bismuth), or the like may be used. In this specification, one conductivity type is defined as n-type, and the opposite conductivity type is defined as p-type.

The light emitting section 3 is formed by laminating a plurality of semiconductor layers on the first surface 7a of the semiconductor substrate 7, as shown in FIG. 2(a). The light emitting portion 3 can be formed by epitaxial growth on the semiconductor substrate 7 by, for example, a MOCVD (Metal-Organic Chemical Vapor Deposition) apparatus. The light emitting unit 3 of this embodiment can emit infrared light with a wavelength of 850 nm, for example.

The plurality of semiconductor layers have buffer layers 81 laminated on the first surface 7 a of the semiconductor substrate 7 . The buffer layer 81 can buffer differences in lattice constants at interfaces between the semiconductor substrate 7 and the plurality of semiconductor layers. The buffer layer 81 may be made of GaAs (gallium arsenide), for example.

The multiple semiconductor layers have an n-type contact layer 82 laminated on the upper surface of the buffer layer 81 . A cathode electrode of the light emitting section 3 is formed on the upper surface of the n-type contact layer 82 . The n-type contact layer 82 can reduce contact resistance with the electrode. The n-type contact layer 82 can be formed, for example, by doping GaAs with an n-type impurity. As an n-type impurity for GaAs, for example, Si or Se (selenium) may be used.

The multiple semiconductor layers have an n-type cladding layer 83 laminated on the upper surface of the n-type contact layer 82 . The n-type cladding layer 83 can confine holes in the active layer 84 to be described later. The n-type cladding layer 83 can be formed, for example, by doping AlGaAs (aluminum gallium arsenide) with an n-type impurity. For example, Si or Se may be used as an n-type impurity for AlGaAs.

The multiple semiconductor layers have an active layer 84 laminated on the upper surface of the n-type cladding layer 83 . The active layer 84 can emit light by concentration and recombination of carriers such as electrons and holes. That is, the active layer 84 can function as a light emitting layer. The active layer 84 may be made of AlGaAs, for example.

The multiple semiconductor layers have a p-type clad layer 85 laminated on the upper surface of the active layer 84 . The p-type cladding layer 85 can confine electrons in the active layer 84 . The p-type clad layer 85 can be formed, for example, by doping AlGaAs with p-type impurities. As p-type impurities for AlGaAs, Zn (zinc), Mg (magnesium), or C (carbon) may be used, for example.

The multiple semiconductor layers have a p-type contact layer 86 laminated on the upper surface of the p-type cladding layer 85 . The p-type contact layer 86 has an anode electrode of the light emitting section 3 formed on its upper surface. The p-type contact layer 86 can reduce contact resistance with the electrode. The p-type contact layer 86 can be formed, for example, by doping AlGaAs with p-type impurities. The p-type contact layer 86 may be set to have a higher carrier density than the p-type clad layer 85 in order to reduce the contact resistance with the electrode. The connection of the anode electrode to the p-type contact layer 86 and the connection of the cathode electrode to the n-type contact layer 82 are performed by forming an insulating layer so as to cover the above plurality of semiconductor layers, and then forming a p-type contact of this insulating layer. This is done by inserting the respective electrode layers into contact holes (connection holes) respectively formed on the layer 86 and on the n-type contact layer 82 .

As shown in FIG. 2B, a p-type semiconductor region 41 is provided on the first surface 7a of the semiconductor substrate 7. As shown in FIG. As a result, a pn junction is formed at the interface between the n-type semiconductor substrate 7 and the p-type semiconductor region 41, and the light receiving portion 4 can be formed. The p-type semiconductor region 41 is formed by doping the semiconductor substrate 7 with p-type impurities. Since the semiconductor substrate 7 of this embodiment is a Si substrate, p-type impurities include, for example, Zn, Mg, B (boron), In (indium), and the like.

The closer the distance between the light emitting unit 3 and the light receiving unit 4 is (for example, about 3 mm), the smaller the size becomes. There is a risk that the light will be incident on the laser beam, resulting in optical noise. A metal layer such as Cr is provided on the second surface 7b of the semiconductor substrate 7 for bonding with the mounting substrate on which the light emitting/receiving element 1 is mounted. When incident on the metal layer at an angle equal to or greater than the critical angle for total reflection, the incident light is totally reflected, making it easier for the light to enter the light receiving section 4 from within the semiconductor substrate 7 .

The light emitting/receiving element 1 of this embodiment has a semiconductor layer 8 on the second surface 7 b of the semiconductor substrate 7 . As a constituent material of the semiconductor layer 8 located on the second surface 7b, a semiconductor material having a higher refractive index than that of the constituent material of the semiconductor substrate 7 is used. By using a semiconductor material having such a refractive index, reflection of leaked light at the boundary between the semiconductor substrate 7 and the semiconductor layer 8 is reduced, and the amount of light incident on the light receiving section 4 is reduced. Thereby, the occurrence of optical noise in the light emitting/receiving element 1 can be reduced.

If the refractive index of the semiconductor layer 8 is greater than that of the semiconductor substrate 7 , the leaked light that has passed through the semiconductor substrate 7 and reached the boundary with the semiconductor layer 8 is not totally reflected. As a result, the amount of light reflected at the boundary between the semiconductor substrate 7 and the semiconductor layer 8 and incident on the light receiving section 4 can be reduced. Part of the leaked light that has passed through the semiconductor layer 8 is reflected at the boundary between the semiconductor layer 8 and the outside, and part of it is transmitted to the outside. The light reflected in the semiconductor layer 8 returns to the semiconductor substrate 7 , but the leaked light is attenuated in the semiconductor substrate 7 and in the semiconductor layer 8 as the light travels repeatedly. In the light emitting/receiving element 1 of the present embodiment, the leakage light incident on the light receiving section 4 is thus reduced, and the occurrence of optical noise is reduced.

Assuming that the refractive index of the constituent material of the semiconductor substrate 7 is n1 and the refractive index of the constituent material of the semiconductor layer 8 is n2, n2>n1. The refractive index in the present disclosure is the refractive index at the wavelength of light (leakage light) emitted from the light emitting section 3 . In this embodiment, for example, since the wavelength of the light emitted from the light emitting section 3 is 850 nm, the refractive index is the refractive index at the wavelength of 850 nm. In this embodiment, for example, the constituent material of the semiconductor substrate 7 is Si, and the refractive index n1 is 3.42. The constituent material of the semiconductor layer 8 is, for example, one or more selected from Ge (germanium), GaAs, InP (indium phosphide), and InAs (indium arsenide). Ge has a refractive index n2 of 4.6, GaAs has a refractive index n2 of 3.63, InP has a refractive index n2 of 3.44, and InAs has a refractive index n2 of 3.71. , and any semiconductor material has a refractive index n2>refractive index n1.

The thickness of the semiconductor layer 8 may be appropriately set according to the semiconductor material forming the semiconductor layer 8, and is, for example, 400 to 1000 nm if the constituent material is Ge. The method of forming the semiconductor layer 8 may be appropriately selected according to the semiconductor material forming the semiconductor layer 8. If the constituent material is Ge, the semiconductor layer 8 can be formed, for example, by vapor deposition.

FIG. 3 is a schematic cross-sectional view showing a light emitting/receiving element that is another embodiment of the present disclosure. The light emitting/receiving element 1A of the present embodiment differs from the light emitting/receiving element 1 described above only in that the first surface 7a of the semiconductor substrate 7 also has a semiconductor layer 8A. and detailed description is omitted. The semiconductor layer 8A is located on the first surface 7a of the semiconductor substrate 7 and between the light emitting section 3 and the light receiving section 4. As shown in FIG.

As described above, part of the leaked light from the light emitting unit 3 into the semiconductor substrate 7 is reflected at the boundary between the semiconductor substrate 7 and the semiconductor layer 8 and the boundary between the semiconductor layer 8 and the outside, and is reflected inside the semiconductor substrate 7. return. This return light is reflected at the boundary between the first surface 7a of the semiconductor substrate 7 and the outside (for example, air). In the present embodiment, by providing the semiconductor layer 8A on the first surface 7a, similarly to the semiconductor layer 8, return light reaching the boundary between the semiconductor substrate 7 and the semiconductor layer 8A on the first surface 7a is not totally reflected. passes through the semiconductor layer 8A and is attenuated. This further reduces the occurrence of optical noise in the light emitting/receiving element 1A.

As with the semiconductor layer 8, the constituent material of the semiconductor layer 8A may be, for example, one or more selected from Ge, GaAs, InP, and InAs. They may be the same or different.

The thickness of the semiconductor layer 8A may be appropriately set according to the semiconductor material forming the semiconductor layer 8A. The semiconductor layer 8A can be formed by a method similar to that of the semiconductor layer 8. FIG.

4A and 4B are schematic diagrams showing a light receiving and emitting element module according to an embodiment of the present disclosure, where (a) shows a plan view and (b) shows a cross-sectional view. The light emitting/receiving element module 100 includes the light emitting/receiving element 1 described above, a wiring board 2 on which the light emitting/receiving element 1 is mounted, and an optical member 9 . Although the light emitting/receiving element module 100 of the present embodiment includes the light emitting/receiving element 1, it may include the light emitting/receiving element 1A instead of the light emitting/receiving element 1. FIG. The light emitting/receiving element module 100 may be used with any direction facing up or down. Z-axis direction) is used as a reference, and terms such as upper surface and lower surface are used.

The light emitting/receiving element module 100 can irradiate an object to be irradiated with light from the light emitting unit 3 and receive reflected light from the object by the light receiving unit 4 . As a result, the light emitting/receiving element module 100 can sense the surface state of the object to be irradiated.

The light emitting/receiving element module 100 is installed in, for example, an image forming apparatus such as a copier or a printer, and used to detect position information, distance information, density information, or the like of an irradiated object such as toner or media. Further, the light emitting/receiving element module 100 may be mounted on, for example, a machine tool to sense the surface state of a workpiece. Note that the light emitting/receiving element module 100 is not limited to the above example, and can be mounted on various devices.

The wiring substrate 2 is mounted with the light emitting/receiving element 1 and can support the light emitting/receiving element 1 . The wiring board 2 is electrically connected to an external device so that, for example, a bias voltage can be applied to the light-emitting portion 3 and the light-receiving portion 4, and an electric signal received and output by the light-receiving portion 4 can be taken out. can.

The wiring board 2 may have a shape such as a rectangular plate shape, for example. For the wiring board 2, for example, a resin board or a ceramic board can be used. The wiring substrate 2 of this embodiment is, for example, a resin substrate. In the present disclosure, a resin substrate refers to a substrate in which the insulating material of the wiring substrate 2 is made of a resin material. A ceramic substrate refers to a substrate in which the insulating material of the wiring substrate 2 is made of a ceramic material. The wiring board 2 can be formed by a conventionally known method.

The light emitting/receiving element 1 has the semiconductor layer 8 side (the second surface 7 b side of the semiconductor substrate 7 ) bonded to the upper surface of the wiring board 2 . For example, the semiconductor layer 8 can be joined to the wiring substrate 2 using solder or brazing material. Moreover, a metal layer such as Cr or Au may be formed on the surface of the semiconductor layer 8 in order to increase the bonding strength between the light emitting/receiving element 1 and the wiring board 2 .

The optical member 9 includes a first lens 12 through which light emitted from the light emitting unit 3 is transmitted, and a second lens 13 through which light incident on the light receiving unit 4 is transmitted. can be Each of the first lens 12 and the second lens 13 is, for example, a convex lens, a spherical lens, or an aspherical lens. The support portion 10 can support the first lens 12 and the second lens 13 . The column 11 is provided on the lower surface of the support section 10 and can support the support section 10 .

The first lens 12 and the second lens 13 (hereinafter sometimes referred to as lenses 12 and 13) may be made of, for example, a translucent material. Translucent materials that can be used include, for example, thermosetting resins such as silicone resins, urethane resins and epoxy resins, plastics such as thermoplastic resins such as polycarbonate resins and acrylic resins, sapphire and inorganic glass. The lenses 12 and 13 can be formed by injection molding or the like, for example. In the optical member 9, the lenses 12 and 13 need only be translucent, and the supporting portion 10 and the strut 11 need not be translucent.

The support portion 10 has a function of holding the lenses 12 and 13 . The support portion 10 may be plate-shaped, for example. The support portion 10 may hold the lenses 12 and 13 by being formed integrally with the lenses 12 and 13, and may hold the lenses 12 and 13 by fitting the lenses 12 and 13 into the support portion 10. good too. Note that the term “integral” means that the lenses 12 and 13 and the support portion 10 are continuous without joints. That is, lenses 12, 13 and haptics 10 may be formed simultaneously from the same material in one process.

The strut 11 supports the support portion 10 holding the lenses 12 and 13, and thus can support the lenses 12 and 13. As shown in FIG. The lenses 12 and 13 and the supporting portion 10 are positioned above and away from the light emitting portion 3 and the light receiving portion 4 . The support 11 extends from the lower surface of the support portion 10 to the wiring board 2 , and the lower tip of the support 11 is in contact with the upper surface of the wiring board 2 . The distance between the first lens 12 and the light emitting section 3 and the distance between the second lens 13 and the light receiving section 4 can be set to appropriate distances depending on the length of the post 11 . For example, as compared with the case of performing positioning in the vertical direction using a frame-like member or the like, the support 11 has a smaller area in contact with the wiring board 2, so that the influence of the shape of the upper surface of the wiring board 2 on the positioning accuracy is reduced. be able to. Therefore, the displacement of the lenses 12 and 13 in the vertical direction can be more effectively reduced, and the sensing performance of the light emitting/receiving element module 100 can be improved.

The end face of the support 11 on the side of the wiring board 2 may be, for example, a convex surface. Since the contact between the post 11 and the wiring board 2 can be made close to point contact, the influence of the shape of the upper surface of the wiring board 2 on the positioning accuracy can be effectively reduced. Therefore, vertical positional displacement can be reduced more effectively. In addition, by forming the tip surface of the support 11 into a curved surface, it is possible to reduce the occurrence of chipping at the tip of the support 11 as compared with the case where the tip is sharp.

The first lens 12, the second lens 13, the supporting portion 10, and the strut 11 may be integrally formed. That is, the optical member 9 may be integrally formed. Also, in other words, the first lens 12, the second lens 13, the supporting portion 10, and the strut 11 may have no boundaries at the contact points of the constituent members, and the constituent members may be continuous. As a result, variations in the positional relationship among the constituent members can be reduced, for example, compared to the case where the constituent members of the optical member 9 are separately produced and then adhered to form the optical member 9 .

Further, since the light-emitting portion 3 and the light-receiving portion 4 of the light-receiving and emitting element 1 are formed on the single semiconductor substrate 7, the light-emitting portion 3 and the light-receiving portion 4 may be mounted on the wiring board 2 as separate elements. In comparison, variations in the positional relationship between the light emitting section 3 and the light receiving section 4 can be reduced.

The light emitting/receiving element module 100 of this embodiment further has a light shielding body 6 . The light shielding body 6 can reduce the reception of unintended light (stray light) by the light receiving section 4 above and to the side of the light emitting/receiving element 1 . The light shielding body 6 is arranged between the optical member 9 and the wiring board 2 so as to surround the light emitting section 3 and the light receiving section 4 . As a result, the light shielding body 6 can reduce the reception of stray light by the light receiving section 4 as described above.

The light shielding body 6 is made of, for example, general-purpose plastics such as polypropylene resin (PP), polystyrene resin (PS), vinyl chloride resin (PVC), polyethylene terephthalate resin (PET), acrylonitrile/butadiene/styrene resin (ABS), polyamide resin ( PA) Engineering plastics such as polycarbonate resin (PC), super engineering plastics such as liquid crystal polymer, and metal materials such as aluminum (Al) and titanium (Ti) may be used. The light shielding body 6 can be formed by, for example, injection molding.

The light shielding body 6 has a wall portion 14 and a lid portion 15 . The wall portion 14 may be any frame-shaped member that surrounds the light emitting portion 3 and the light receiving portion 4 . The lid portion 15 may be arranged so as to be fitted into the upper end side opening of the frame-shaped wall portion 14 . The lid portion 15 also has a light passing portion 16 positioned on the optical path from the light emitting portion 3 to the first lens 12 and on the optical path from the second lens 13 to the light receiving portion 4 . The light passing portion 16 of the present embodiment is a through hole penetrating the lid portion 15 in the thickness direction.

The wall portion 14 has a through hole 17 penetrating vertically. A support 11 of the optical member 9 is arranged in the through hole 17 . In other words, the support 11 is inserted into the through hole 17 . Since the support 11 is covered with the wall portion 14 of the light shielding body 6, the support 11 can be protected, and it is possible to reduce breakage of the support 11 due to external impact, for example.

Also, the ends of the plurality of posts 11 on the side of the wiring board 2 may be tapered toward the ends. When manufacturing the light receiving and emitting element module 100, the optical member 9 can be easily inserted into the light blocking body 6, and the production efficiency of the light emitting and receiving element module 100 can be improved.

The upper surface of the light shielding body 6 may be positioned below and away from the lower surface of the support portion 10 of the optical member 9 . That is, there may be a gap between the upper surface of the light shielding body 6 and the lower surface of the support portion 10 . For example, it is possible to reduce the possibility that the optical member 9 is pushed up due to the thermal expansion of the light blocking member 6 or the like. Therefore, the distances between the lenses 12 and 13 and the light emitting unit 3 and the light receiving unit 4 can be easily maintained, and the sensing performance of the light emitting/receiving element module 100 can be maintained.

The outer edge of the light shielding body 6 may be located outside the outer edge of the optical member 9 when the light emitting/receiving element module 100 is viewed from above. Further, the upper surface of the outer edge portion of the light blocking member 6 may have a convex portion 18 protruding upward. As a result, for example, the optical member 9 can be protected from external stress. In addition, in the present embodiment, the convex portion 18 is continuously formed so as to surround the support portion 10 .

The optical member 9 may be fixed to the inner surface of the convex portion 18 of the light shielding body 6 and the side surface of the support portion 10 via an adhesive. The amount of adhesive entering between the lower surface of the support part 10 and the upper surface of the lid part 15 can be reduced, and the thermal expansion of the adhesive can reduce the displacement of the lenses 12 and 13 in the vertical direction. be able to.

Further, the positioning of the light shielding member 6 is performed using the through holes 17 in this embodiment. , may be aligned by combining them.

FIG. 5 is a schematic diagram showing a sensor device that is an embodiment of the present disclosure. 5 indicates the path of light emitted from the light emitting section 3 and received by the light receiving section 4. The two-dot chain line arrows shown in FIG. The sensor device 200 includes the light emitting/receiving element module 100 described above and a control circuit 101 . The control circuit 101 is electrically connected to the light emitting/receiving element module 100, controls the emitted light emitted from the light emitting section 3, and detects the amount of light received by the light receiving section 4. FIG. The control circuit 101 includes, for example, a drive circuit for driving the light emitting unit 3, an arithmetic circuit for processing the output (current or voltage, etc.) from the light receiving unit 4, a communication circuit for communicating with an external device, and the like. you can stay The sensor device 200 can output, for example, the output from the light receiving unit 4 or the calculation result of the calculation circuit to the outside as the detection result by sensing by the control circuit 101 .

(Example)
A light emitting/receiving element having a Ge layer as a semiconductor layer on the second surface of the semiconductor substrate was prepared as an example, and a light emitting/receiving element having a Cr layer instead of the semiconductor layer was prepared as a comparative example. The thickness of the semiconductor substrate in the example and the comparative example was set to 350 μm, the thickness of the Ge layer in the example was set to 500 nm, and the thickness of the Cr layer in the comparative example was set to 30 nm.

Examples and comparative examples were operated under the conditions shown below, and the reduction rate of leaked light was evaluated.
・Light-emitting part current value: 6mA
・Light-receiving part normal output: 3V

A method for measuring leaked light is as follows.
(1) With an object to be irradiated, adjust the output of the light receiving unit so that it becomes a normal output of 3 V (2) Measure the output of the light receiving unit without an object to be irradiated (3) Leakage light (% ) = (measured output/normal output) x 100 In (2), since the object to be irradiated is not placed, the light receiving part does not receive the reflected light from the object to be irradiated, and the measured output is , can be attributed to leakage light.

Measure the leakage light (%) of the example, measure the leakage light (%) of the comparative example,
Leakage light reduction rate (%) = ((Leakage light of Example - Leakage light of Comparative example) / Leakage light of Comparative example) x 100
was calculated.

The measured output of the example was 0.111 V and the leakage light was 3.7%. The measured output of the comparative example was 0.138 V, and the leakage light was 4.6%. From these results, it was found that the leakage light reduction rate was 20%, and that the amount of leakage light incident on the light receiving section could be reduced in the example.

REFERENCE SIGNS LIST 1, 1A light receiving and emitting element 2 wiring board 3 light emitting section 4 light receiving section 6 light shielding body 7 semiconductor substrate 7a first surface 7b second surface 8, 8A semiconductor layer 9 optical member 10 support section 11 post 12 first lens 13 second lens 14 wall portion 15 lid portion 16 light passing portion 17 through hole 18 convex portion 100 light emitting/receiving element module 101 control circuit 200 sensor device

Claims (5)

a semiconductor substrate having a first surface and a second surface opposite the first surface;
a light-emitting portion and a light-receiving portion located on the first surface;
a semiconductor layer located on the second surface;
A light emitting/receiving device, wherein a refractive index of a constituent material of the semiconductor layer is higher than a refractive index of a constituent material of the semiconductor substrate. The constituent material of the semiconductor layer is one or more selected from Ge, GaAs, InP and InAs,
2. The light emitting/receiving device according to claim 1, wherein the semiconductor substrate is made of Si. 3. The light receiving and emitting device according to claim 1, wherein said semiconductor layer has a thickness of 400 to 1000 nm. a light receiving and emitting device according to any one of claims 1 to 3;
a wiring board on which the light emitting/receiving element is mounted;
A light emitting/receiving element module comprising an optical member including a first lens through which light emitted from the light emitting section is transmitted and a second lens through which light incident on the light receiving section is transmitted. a light emitting/receiving element module according to claim 4;
a control circuit that is electrically connected to the light emitting/receiving element module, controls light emitted from the light emitting unit, and detects an amount of light received by the light receiving unit.

Images