JP6413518B2 - Optical semiconductor device, optical sensor, and manufacturing method of optical semiconductor device - Google Patents

Description

  The present invention relates to an optical semiconductor element, an optical sensor, and an optical semiconductor element manufacturing method.

  Conventionally, an optical semiconductor element has been used to detect light. In addition, an optical sensor that captures an image by arranging a plurality of optical semiconductor elements in a two-dimensional array is used.

  The optical sensor has sensitivity to a predetermined wavelength to be detected according to the application.

  For example, there is an optical semiconductor element having sensitivity in the infrared wavelength region. Such an optical semiconductor element that detects infrared rays is used for detecting a heat source or monitoring a dark field. An optical semiconductor element that detects infrared rays includes, for example, one that detects two wavelengths: a MW band having a wavelength of 3 to 5 μm and an LW band having a wavelength of 8 to 10 μm.

  Such an optical semiconductor element has an active layer sensitive to infrared rays of the first wavelength and an active layer sensitive to infrared rays of the second wavelength, and is formed by laminating these two active layers. There is something.

  FIG. 1 is a diagram showing a conventional optical semiconductor device.

  The optical semiconductor device 100 includes a substrate 11, a buffer layer 12 disposed on the substrate 11, a first electrode layer 13 disposed on the buffer layer 12, and a first active disposed on the first electrode layer 13. A layer 14 and a second electrode layer 15 disposed on the first active layer 14 are provided. A second active layer 16 is disposed on the second electrode layer 15, and a third electrode layer 17 is disposed on the second active layer 16.

  Each of the first active layer 14 and the second active layer 16 receives light having a predetermined wavelength incident from the substrate 11 side, and generates an electrical signal. The first active layer 14 is sensitive to light of the first wavelength, and the second active layer 16 is sensitive to light of the second wavelength, each having sensitivity to a different wavelength.

  A predetermined voltage is applied between the first electrode layer 13 and the second electrode layer 15, and the electric signal of the first active layer 14 is read out. Further, a predetermined voltage is applied between the third electrode layer 17 and the second electrode layer 15, and the electric signal of the second active layer 16 is read out.

  An optical coupling layer 120 and a reflective layer 18 are disposed on the third electrode layer 17. The optical coupling layer 120 is formed of a diffraction grating having a grating period of the second wavelength, and has a function of selectively irregularly reflecting the light of the second wavelength and returning the light into the optical semiconductor element. By exciting the electric field component of the light returned into the optical semiconductor element due to the irregular reflection of the optical coupling layer 120 by interacting with the carriers in the second active layer 16, the light receiving sensitivity to the light of the second wavelength is enhanced. .

JP 2010-114381 A International Publication No. 2007-029714

  The optical coupling layer 120 of the optical semiconductor element 10 shown in FIG. 1 has a function of improving the external quantum efficiency by irregularly reflecting light of the second wavelength back into the optical semiconductor element. There is no function to diffusely reflect the light. Therefore, the external quantum efficiency for the first wavelength light is smaller than that for the second wavelength light.

  Therefore, an optical coupling layer having a diffraction grating having a grating period of the first wavelength and the second wavelength has been proposed.

  FIG. 2 is a diagram showing another optical semiconductor element of the conventional example.

  The optical semiconductor element 200 includes an optical coupling layer 220 including a diffraction grating having a grating period of a first wavelength and a diffraction grating having a grating period of a second wavelength. A diffraction grating having a grating period of the first wavelength is formed in one half region of the optical coupling layer 220, and a diffraction grating having a grating period of the second wavelength is formed in the other half region.

  The optical coupling layer 220 has a function of irregularly reflecting the light of the first wavelength and the second wavelength and returning the light into the optical semiconductor element.

  However, in the optical semiconductor element 200 shown in FIG. 2, the area of the diffraction grating having the grating period of the second wavelength is reduced to half that of the optical semiconductor element 100 shown in FIG. Decreases. For the same reason, in the optical semiconductor element 200 shown in FIG. 2, there is a possibility that the light receiving sensitivity with respect to the light of the first wavelength is not sufficient.

  This specification makes it a subject to provide the optical semiconductor element which improved the sensitivity with respect to two wavelengths.

  According to an embodiment of the optical semiconductor element disclosed in the present specification, a first electrode layer, a first active layer disposed on the first electrode layer and having sensitivity to a first wavelength, and the first active layer A second electrode layer disposed on the second electrode layer, a second active layer disposed on the second electrode layer and sensitive to a second wavelength; a third electrode layer disposed on the second active layer; A first optical coupling layer disposed on the first active layer side with respect to the second electrode layer and selectively guiding light having a first wavelength of incident light to the first active layer; and A second optical coupling layer which is disposed on the second active layer side with respect to the electrode layer and selectively guides light having a second wavelength of incident light to the second active layer.

  Moreover, according to one form of the optical sensor disclosed in this specification, the first electrode layer, the first active layer disposed on the first electrode layer and having sensitivity to the first wavelength, and the first active layer are provided. A second electrode layer disposed on the layer, a second active layer disposed on the second electrode layer and sensitive to a second wavelength, and a third electrode layer disposed on the second active layer, A first optical coupling layer disposed on the first active layer side with respect to the second electrode layer and selectively guiding light having a first wavelength of incident light to the first active layer; and the second A plurality of optical semiconductor elements having a second optical coupling layer that is disposed on the second active layer side with respect to the electrode layer and selectively guides light having a second wavelength of incident light to the second active layer And a signal processing unit that reads an electrical signal of each of the optical semiconductor elements.

  Furthermore, according to one form of the manufacturing method of the optical semiconductor element disclosed in this specification, the first electrode layer is formed on the substrate, and the first electrode having sensitivity to the first wavelength is formed on the first electrode layer. An active layer is formed, a second electrode layer is formed on the first active layer, a second active layer having sensitivity to a second wavelength is formed on the second electrode layer, and the second active layer is formed. A third electrode layer is formed thereon, a second optical coupling layer for selectively guiding light having the second wavelength to the second light absorption layer is formed on the third electrode layer, and the substrate is processed. Thus, a first optical coupling layer that selectively guides light having the first wavelength to the first light absorption layer is formed.

  According to one mode of the optical semiconductor element disclosed in the present specification described above, sensitivity to two wavelengths is improved.

  Moreover, according to one form of the optical sensor disclosed in the present specification described above, sensitivity to two wavelengths is improved.

  Furthermore, according to one mode of the method for manufacturing an optical semiconductor element disclosed in the present specification, an optical semiconductor element having improved sensitivity to two wavelengths can be obtained.

  The objects and advantages of the invention will be realized and obtained by means of the elements and combinations particularly pointed out in the appended claims.

  Both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention as claimed.

It is a figure which shows the optical semiconductor element of a prior art example. It is a figure which shows the other optical semiconductor element of a prior art example. It is a figure which shows one Embodiment of the optical semiconductor element disclosed by this specification. It is a calculation result of the electric field strength distribution of an optical semiconductor element. It is a figure which shows the modification of an optical semiconductor element. It is a figure which shows one Embodiment of the optical sensor disclosed in this specification. It is a figure which shows the process (the 1) of one Embodiment of the manufacturing method of an optical sensor. It is a figure which shows the process (the 2) of one Embodiment of the manufacturing method of an optical sensor. It is a figure which shows the process (the 3) of one Embodiment of the manufacturing method of an optical sensor. It is a figure which shows the process (the 4) of one Embodiment of the manufacturing method of an optical sensor. It is a figure which shows the process (the 5) of one Embodiment of the manufacturing method of an optical sensor. It is a figure which shows the process (the 6) of one Embodiment of the manufacturing method of an optical sensor. It is a figure which shows the process (the 7) of one Embodiment of the manufacturing method of an optical sensor. It is a figure which shows the process (the 8) of one Embodiment of the manufacturing method of an optical sensor. It is a figure which shows other embodiment of an optical semiconductor element.

  Hereinafter, a preferred embodiment of the optical semiconductor device disclosed in this specification will be described with reference to the drawings. However, the technical scope of the present invention is not limited to these embodiments, but extends to the invention described in the claims and equivalents thereof.

  FIG. 3 is a diagram showing an embodiment of an optical semiconductor device disclosed in this specification.

  The optical semiconductor element 10 of this embodiment has good sensitivity to light of two different wavelengths. The optical semiconductor element 10 receives light from the incident surface 10a, detects light having two predetermined wavelengths, and converts it into an electrical signal.

  The optical semiconductor element 10 includes a first optical coupling layer 20, a buffer layer 12 disposed on the first optical coupling layer 20, a first electrode layer 13 disposed on the buffer layer 12, and a first electrode layer 13. A first active layer 14 disposed above and a second electrode layer 15 disposed on the first active layer 14 are provided.

  The optical semiconductor element 10 is disposed on the second active layer 16 disposed on the second electrode layer 15, the third electrode layer 17 disposed on the second active layer 16, and the third electrode layer 17. The second optical coupling layer 21 and the reflective layer 18 disposed on the second optical coupling layer 21.

  Each of the first active layer 14 and the second active layer 16 receives light having a predetermined wavelength incident from the incident surface 10a and generates an electrical signal. The first active layer 14 is sensitive to light of the first wavelength, and the second active layer 16 is sensitive to light of the second wavelength, each having sensitivity to the same or different wavelength. In the present embodiment, each of the first active layer 14 and the second active layer 16 has sensitivity to different wavelengths.

  A predetermined voltage is applied between the first electrode layer 13 and the second electrode layer 15, and the electric signal of the first active layer 14 is read out. Further, a predetermined voltage is applied between the third electrode layer 17 and the second electrode layer 15, and the electric signal of the second active layer 16 is read out. In this way, the optical semiconductor element 10 can detect the first wavelength light and the second wavelength light.

  The first active layer 14 selectively absorbs light of the first wavelength and generates an electrical signal. From the viewpoint of high sensitivity at a predetermined wavelength, the first active layer 14 is preferably formed using a quantum well or a quantum dot.

  The second active layer 16 selectively absorbs light having a second wavelength different from the first wavelength to generate an electrical signal. From the viewpoint of high sensitivity at a predetermined wavelength, the second active layer 16 is preferably formed using quantum wells or quantum dots.

  Since the first active layer 14 and the second active layer 16 are one-dimensionally quantized in the stacking direction of the layers, carriers in the first active layer 14 and the second active layer 16 are relative to the stacking surface. The interaction with the electric field component of light incident in a perpendicular direction is weak.

  Therefore, the first optical coupling layer 20 is disposed on the first active layer 14 side with respect to the second electrode layer 15, and selectively transmits light having the first wavelength of incident light to the first active layer 14. Lead.

  Similarly, the second optical coupling layer 21 is disposed on the second active layer 16 side with respect to the second electrode layer 15, and selectively selects light having the second wavelength of incident light from the second active layer 16. Lead to.

  The first optical coupling layer 20 is formed of a diffraction grating having a grating period of the first wavelength, and has a function of selectively irregularly reflecting the light of the first wavelength and returning the light into the optical semiconductor element. An optical semiconductor element for light of the first wavelength is obtained by exciting the electric field component of the light returned into the optical semiconductor element due to the irregular reflection of the first optical coupling layer 20 by interacting with the carriers in the first active layer 14. The light receiving sensitivity of 10 is increased.

  Similarly, the second optical coupling layer 21 is formed of a diffraction grating having a grating period of the second wavelength, and selectively diffuses and reflects light of the second wavelength to return the light into the optical semiconductor element. Have. An optical semiconductor element for the light of the second wavelength is obtained by exciting the electric field component of the light returned into the optical semiconductor element due to the irregular reflection of the second optical coupling layer 21 by interacting with the carriers in the second active layer 16. The light receiving sensitivity of 10 is increased.

  In addition, the optical semiconductor element 10 uses the reflective layer 18 to return incident light to the inside of the optical semiconductor element, thereby allowing the carriers of the first active layer 14 and the second active layer 16 to interact with light. Is increasing.

  Of the first active layer 14 and the second active layer 16, disposing the active layer having sensitivity to a relatively short wavelength on the incident surface 10 a side reduces light loss and increases sensitivity. To preferred. In the present embodiment, since the first wavelength λM is shorter than the second wavelength λL, the first active layer 14 sensitive to the light having the first wavelength λM is disposed on the incident surface 10a side. A first optical coupling layer 20 that selectively guides light having the first wavelength λM to the first active layer 14 is disposed on the first active layer 14 side with respect to the second electrode layer 15.

  If the second active layer 16 having sensitivity to the second wavelength λL having a relatively long wavelength is disposed on the incident surface 10a side, when the light passes through the second active layer 16, the first wavelength λM A part of the light may be absorbed by the second active layer 16. On the other hand, since the light having the relatively long second wavelength λL is hardly absorbed by the first active layer 14, the second active layer 16 having sensitivity to the relatively short first wavelength is incident on the incident surface 10a. There is little influence of placing on the side.

  Next, functions of the first optical coupling layer 20 and the second optical coupling layer 21 will be described below with reference to the drawings.

  First, light including the first wavelength λM and the second wavelength λL is irradiated on the incident surface 10a. The angle at which light enters the incident surface 10a is generally closer to perpendicular to the incident surface 10a than parallel.

  The light incident on the optical semiconductor element 10 is after a part of the light having the first wavelength λM is absorbed by the first active layer 14 and a part of the light having the second wavelength λL is absorbed by the second active layer 16. The second optical coupling layer 21 is reached.

  The second light coupling layer 21 selectively diffracts the light having the second wavelength λL to diffusely reflect the light reaching the second light coupling layer 21. In addition, light having a wavelength other than the second wavelength λL is specularly reflected by the reflective layer 18 and returns to the inside of the optical semiconductor element.

  Since the ratio of the light having the second wavelength λL that is irregularly reflected by the second optical coupling layer 21 travels in the layer direction of the second active layer 16 increases, the interaction with the carriers in the second active layer 16 increases. Thereby, the sensitivity with respect to the light of the 2nd wavelength of the optical semiconductor element 10 is improved.

  On the other hand, light having a wavelength other than the second wavelength λL specularly reflected by the reflection layer 18 is partially absorbed by the first active layer 14 when passing through the first active layer 14. The first optical coupling layer 20 is reached.

  The first light coupling layer 20 selectively diffracts the light having the first wavelength λM to diffusely reflect the light reaching the first light coupling layer 20. Since the ratio of the light having the first wavelength λM that is irregularly reflected by the first optical coupling layer 20 travels in the layer direction of the first active layer 14 increases, the interaction with the carriers in the first active layer 14 increases. Thus, the light receiving sensitivity of the optical semiconductor element 10 with respect to the first wavelength light is increased.

  Further, a part of the light having a wavelength other than the first wavelength λM is specularly reflected at the boundary between the first optical coupling layer 20 and the buffer layer 12 and returns to the inside of the optical semiconductor element 10. The light returning to the inside of the optical semiconductor element 10 repeats the above-described process. In addition, part of light having a wavelength other than the first wavelength λM goes out of the optical semiconductor element 10.

  The material forming the first optical coupling layer 20 preferably has a refractive index different from that of the buffer layer 12 in functioning as a diffraction grating. Moreover, it is preferable that the material forming the first optical coupling layer 20 has a low absorption coefficient for light having the first wavelength λM and the second wavelength λL.

  FIG. 4 shows the calculation result of the electric field intensity distribution of the optical semiconductor element.

  FIG. 4 shows an optical semiconductor device 10 having a first active layer 14 sensitive to light having a first wavelength λM of 4.7 μm and a second active layer 16 sensitive to light having a second wavelength λL of 10.8 μm. Shows the calculation results when light having a wavelength of 4.7 μm is irradiated.

  The material for forming the optical semiconductor element 10 will be described in the description of the method for manufacturing the optical semiconductor element described later.

  Calculation of the electric field strength distribution of the optical semiconductor element was performed by solving the boundary value problem of the Maxwell equation using an electromagnetic field simulator.

  The vertical axis in FIG. 4 indicates the position in the thickness direction of the optical semiconductor element, and the horizontal axis indicates the position in the layer direction of the optical semiconductor element. 4 indicates the electric field intensity of the electric field component Ey in the optical semiconductor element.

  In addition to the calculation shown in FIG. 4, the electric field intensity distribution in the optical semiconductor element was similarly calculated for the optical semiconductor element in which the first optical coupling layer was not disposed.

  When both calculation results were compared, it was found that the integrated amount of the electric field component Ey in the first active layer was increased by 1.08 times by arranging the first optical coupling layer.

  In addition to the calculation shown in FIG. 4, when the electric field intensity distribution in the optical semiconductor element when irradiated with light having a wavelength of 10.8 μm was calculated, the value of the electric field component Ey in the optical semiconductor element changed. Was not seen. That is, it is considered that the arrangement of the first optical coupling layer does not affect the light receiving sensitivity of the second wavelength having a relatively long wavelength.

  According to the optical semiconductor element 10 of the present embodiment described above, the sensitivity to two wavelengths is improved. Therefore, the optical semiconductor element 10 improves both the external quantum efficiencies for the light of the first wavelength and the second wavelength.

  In the optical semiconductor device of the above-described embodiment, the active layer and the optical coupling layer that are sensitive to relatively short wavelengths are arranged on the incident surface 10a side, but the active layer that is sensitive to relatively long wavelengths is active. The layer and its optical coupling layer may be arranged on the incident surface 10a side. Even if such a configuration is used, an effect of improving the sensitivity to two wavelengths can be obtained.

  FIG. 5 is a diagram showing a modification of the optical semiconductor element.

  In the optical semiconductor device 10 of this modification, the first optical coupling layer 20 is disposed adjacent to the first active layer 14, and the second optical coupling layer 21 is disposed adjacent to the second active layer 16. . Specifically, the first photocoupling layer 20 is disposed between the first active layer 14 and the first electrode layer 13, and the second photocoupling layer 21 is composed of the second active layer 16 and the third electrode layer 17. Between.

  Further, the first optical coupling layer 20 is disposed on the surface of the second electrode layer 15 on the first active layer 14 side, and the second optical coupling layer 21 is disposed on the second active layer 16 side of the second electrode layer 15. You may arrange | position on a surface.

  Next, an optical sensor in which a plurality of optical semiconductor elements disclosed in this specification are arranged in a two-dimensional array will be described below with reference to the drawings.

  The optical sensor 30 of the present embodiment includes a plurality of optical semiconductor elements 10 arranged in a two-dimensional array, and a signal processing unit 40 that reads an electrical signal of each optical semiconductor element 10. Each optical semiconductor element 10 functions as one pixel of the optical sensor 30. The optical sensor 30 generates an image signal by converting light received by a plurality of optical semiconductor elements 10 arranged in a two-dimensional array into an electrical signal.

  Each optical semiconductor element 10 is arranged on the signal processing unit 40 with the incident surface facing outward. The signal processing unit 40 and each electrode of each optical semiconductor element 10 are electrically connected using a bump or the like (not shown).

  In the example shown in FIG. 6, the optical semiconductor elements 10 are arranged in a two-dimensional array, but the optical semiconductor elements 10 may be arranged in a one-dimensional array.

  Next, one mode of a method for manufacturing an optical sensor disclosed in this specification will be described below with reference to the drawings.

  In this embodiment, in order to make the explanation easy to understand, a manufacturing process of a part of one optical semiconductor element in the optical semiconductor element array included in the optical sensor will be described. Other optical semiconductor element portions are formed in the same manner.

  First, as shown in FIG. 7, a buffer layer 12, a first electrode layer 13 having n-type polarity, a first active layer 14, and a second electrode layer 15 having n-type polarity are formed on a substrate 11. The second active layer 16, the third electrode layer 17 having n-type polarity, and the processed layer 22 are formed in order.

  As a method of forming each layer, for example, molecular beam epitaxy (MBE) or metal organic chemical vapor deposition (MOCVD) can be used.

In this embodiment, a semi-insulating GaAs substrate is used as the substrate 11. The buffer layer was formed using GaAs. The first electrode layer 13, the second electrode layer 15, and the third electrode layer 17 were formed using GaAs doped with Si at a concentration of about 1 × 10 ¹⁸ cm ⁻³ . The first active layer 14 was formed by a quantum well using InGaAs / GaAs / AlGaAs. The number of repetitions of the quantum well was 10 to 50 cycles. The thickness of each layer, the In composition, and the Al composition are determined so as to be sensitive to the first wavelength. The InGaAs layer may be doped with Si. The second active layer 16 was formed by a quantum well using GaAs / AlGaAs. The number of repetitions of the quantum well was 10 to 50 cycles. The thickness of each layer and the Al composition are determined so as to be sensitive to the second wavelength. The GaAs layer may be doped with Si. The processed layer 22 was formed using GaAs doped with Si.

  Next, as shown in FIG. 8, the processed layer 22 is processed into a diffraction grating to form the second optical coupling layer 21. The second optical coupling layer 21 is formed by forming a resist pattern on the processing layer 22 using, for example, a photolithography method, and then exposing the exposed portion of the processing layer 22 using a dry etching method or a wet etching method. It is formed by removing. The grating interval of the diffraction grating is determined so as to coincide with the period of the second wavelength.

  Next, as shown in FIG. 9, the reflective layer 18 is formed so as to cover the second optical coupling layer 21 on the third electrode layer 17. The reflective layer 18 can be formed using, for example, a known metal film forming method such as vacuum deposition or vacuum sputtering. In the present embodiment, the reflective layer 18 is formed using Au.

  Next, as shown in FIG. 10, the third electrode layer 17 and the second active layer 16 located on the second electrode layer 15 are etched so that a part of the second electrode layer 15 is exposed. Is done. Further, the third electrode layer 17, the second active layer 16, the second electrode layer 15, and the first active layer located on the portion of the first electrode layer 13 so that a part of the first electrode layer 13 is exposed. Layer 14 is etched. Further, the third electrode layer 17, the second active layer 16, the second electrode layer 15, and the second electrode layer 15 located on the buffer layer 12, so that the adjacent optical semiconductor elements are electrically insulated and the buffer layer 12 is exposed. The first active layer 14, the buffer layer 12, and the first electrode layer 13 are etched. As a method for etching each layer, for example, a dry etching method or a wet etching method can be used.

  Next, as shown in FIG. 11, after an electrically insulating insulating layer 31 is formed on the reflective layer 18 from the buffer layer 12, an opening 32a exposing the second electrode layer 15 and the reflective layer 18 are exposed. An opening 32 b and an opening 32 c exposing the first electrode layer 13 are formed in the insulating layer 31. The insulating layer 31 also has a function of protecting each layer of the optical semiconductor element 10. In the present embodiment, the insulating layer 31 is formed using SiON. The openings 32a to 32c are formed using, for example, a dry etching method or a wet etching method.

  Next, as shown in FIG. 12, a wiring layer 33 that is electrically connected to the second electrode layer 15 exposed in the opening 32a and extends to the insulating layer 31 on the reflective layer 18 is formed. In addition, a wiring layer 34 that is electrically connected to the first electrode layer 13 exposed in the opening 32 c and extends to the insulating layer 31 on the reflective layer 18 is formed.

  A bump 35 a is formed on the wiring layer 34, and a bump 35 c is formed on the wiring layer 34. A bump 35b is formed on the reflective layer 18 exposed in the opening 32b. Since the reflective layer 18 has electrical conductivity, the bump 35b and the third electrode layer 17 are electrically connected.

  Next, as shown in FIG. 13, the optical semiconductor element 10 is electrically connected to a separately prepared signal processing unit 40. Specifically, the bumps 35a to 35c of the optical semiconductor element 10 and the corresponding bumps 36a to 36b of the signal processing unit 40 are flip-chip bonded.

  Next, as shown in FIG. 14, the substrate 11 is processed into a diffraction grating to form the first optical coupling layer 20 to obtain the optical semiconductor element 10, and the optical sensor 30 having an array of the optical semiconductor elements 10. Complete. The grating interval of the diffraction grating is determined so as to coincide with the period of the first wavelength. The substrate 11 is thinned using, for example, a dry etching method or a wet etching method, and then processed into a diffraction grating using a laser processing method or the like.

  In the above-described embodiment, the first electrode layer 13, the second electrode layer 15, and the third electrode layer 17 of each optical semiconductor element 10 are electrically insulated, but the first electrode layer 13 and the third electrode layer 17 may be formed so as to be integrated with each optical semiconductor element. In this case, each optical semiconductor element 10 is provided with a bump 35b that is electrically connected to the second electrode layer 15, and electrical signals of the first active layer 14 and the second active layer 16 are output from the bump 35b. Is done.

  In the present invention, the optical semiconductor element, the optical sensor, and the method for manufacturing the optical semiconductor element of the above-described embodiment can be appropriately changed without departing from the gist of the present invention. In addition, the configuration requirements of one embodiment can be applied to other embodiments as appropriate.

  For example, FIG. 15 is a diagram showing another embodiment of the optical semiconductor element.

  The optical semiconductor element 10 includes a first optical coupling layer 20, a buffer layer 12 disposed on the first optical coupling layer 20, a first electrode layer 13 disposed on the buffer layer 12, and a first electrode layer 13. A first active layer 14 is provided thereon.

  In addition, the optical semiconductor element 10 includes the third electrode layer 17 disposed on the first active layer 14, the second optical coupling layer 21 disposed on the third electrode layer 17, and the second optical coupling layer 21. The reflective layer 18 is provided.

  The optical semiconductor device of this embodiment does not include the second electrode layer and the second active layer.

  A part of the incident light is reflected by the incident surface 10 a, and not all the incident light enters the first active layer 14 via the buffer layer 12. On the other hand, from the viewpoint of increasing the light receiving sensitivity, it is desired to reduce the amount of light reflected by the incident surface 10a.

  As a method for reducing the amount of light reflected by the incident surface 10a, for example, an antireflection film (AR coating) may be formed on the incident surface 10a. The antireflection film is formed on the incident surface 10a of the thin optical semiconductor element 10. Is generally difficult to form.

  Therefore, the amount of light reflected by the incident surface 10a can be reduced by arranging the first optical coupling layer 20 on the incident surface 10a. For example, according to the calculation of the electric field intensity distribution of the optical semiconductor element using the electromagnetic field simulator, the amount of light reflected by the incident surface 10a can be reduced by 30%.

  Moreover, since the light is diffracted by the incident surface 10a by arranging the first optical coupling layer 20 on the incident surface 10a, an effect of increasing the electric field component in the first active layer 14 is also obtained.

  The first optical coupling layer 20 is formed of a diffraction grating, and the period of the diffraction grating may be the same as the first wavelength at which the first active layer 14 has sensitivity. Moreover, even if the period of the diffraction grating is not the same as the first wavelength, it is possible to obtain the effect of reducing the amount of light reflected by the incident surface 10a and increasing the electric field component in the first active layer 14.

  All examples and conditional words mentioned herein are intended for educational purposes to help the reader deepen and understand the inventions and concepts contributed by the inventor. All examples and conditional words mentioned herein are to be construed without limitation to such specifically stated examples and conditions. Also, such exemplary mechanisms in the specification are not related to showing the superiority and inferiority of the present invention. While embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions or modifications can be made without departing from the spirit and scope of the invention.

DESCRIPTION OF SYMBOLS 10 Optical semiconductor element 10a Incident surface 11 Substrate 12 Buffer layer 13 1st electrode layer 14 1st active layer 15 2nd electrode layer 16 2nd active layer 17 3rd electrode layer 18 Reflective layer 20 1st optical coupling layer 21 2nd light Bonding layer 22 Processing layer 30 Optical sensor 31 Insulating layer 32a, 32b, 32c Opening 33 Wiring layer 34 Wiring layer 35a, 35b, 35c Electrode 36a, 36b, 36c Bump 40 Signal processing unit

Claims (6)

A first electrode layer;
A first active layer disposed on the first electrode layer and sensitive to a first wavelength;
A second electrode layer disposed on the first active layer;
A second active layer disposed on the second electrode layer and sensitive to a second wavelength;
A third electrode layer disposed on the second active layer;
A first optical coupling layer that is disposed on the first active layer side with respect to the second electrode layer and selectively guides light having a first wavelength of incident light to the first active layer;
A second optical coupling layer that is disposed on the second active layer side with respect to the second electrode layer and selectively guides light having a second wavelength of incident light to the second active layer;
A reflective layer disposed on the second optical coupling layer and reflecting light having a first wavelength;
Bei to give a,
The first optical coupling layer is disposed outside the first electrode layer, and the second optical coupling layer is disposed outside the third electrode layer.
An optical semiconductor element comprising a light incident surface on the first electrode layer side, wherein the first wavelength is shorter than the second wavelength . 2. The optical semiconductor device according to claim 1, wherein the first optical coupling layer is disposed adjacent to the first active layer, and the second optical coupling layer is disposed adjacent to the second active layer. It said first optical coupling layer or the second optical coupling layer, the optical semiconductor device according to claim 1 or 2 having a diffraction grating. The first active layer and the second active layer, the optical semiconductor device according to any of claims 1 to 3 having a quantum well or quantum dots. A first electrode layer;
A first active layer disposed on the first electrode layer and sensitive to a first wavelength;
A second electrode layer disposed on the first active layer;
A second active layer disposed on the second electrode layer and sensitive to a second wavelength;
A third electrode layer disposed on the second active layer;
A first optical coupling layer that is disposed on the first active layer side with respect to the second electrode layer and selectively guides light having a first wavelength of incident light to the first active layer;
A second optical coupling layer that is disposed on the second active layer side with respect to the second electrode layer, and selectively guides light having a second wavelength of incident light to the second active layer;
A reflective layer disposed on the second optical coupling layer and reflecting light having a first wavelength;
Have
The first optical coupling layer is disposed outside the first electrode layer, and the second optical coupling layer is disposed outside the third electrode layer.
Provided with a light incident surface on the first electrode layer side, the first wavelength is shorter than the second wavelength,
A plurality of optical semiconductor elements;
A signal processing unit for reading an electrical signal of each of the optical semiconductor elements;
An optical sensor comprising: Forming a first electrode layer on a substrate;
Forming a first active layer sensitive to a first wavelength on the first electrode layer;
Forming a second electrode layer on the first active layer;
Forming a second active layer having sensitivity to a second wavelength on the second electrode layer;
Forming a third electrode layer on the second active layer;
Forming a second optical coupling layer on the third electrode layer for selectively guiding light having the second wavelength to the second light absorption layer ;
Forming a reflective layer for reflecting light having the first wavelength on the second optical coupling layer;
Processing the substrate to form a first optical coupling layer that selectively guides light having a first wavelength to the first light absorption layer ;
Including
A method for manufacturing an optical semiconductor element , comprising a light incident surface on the first electrode layer side, wherein the first wavelength is shorter than the second wavelength .