JPH114046A - Transmitting/receiving photonic ic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent crosstalks between a transmitter and a receiver caused by an electromagnetic coupling generated in a transmitting/receiving photonic pad for optical communication made by laminating a flat light-emitting element and a flat light-receiving element. SOLUTION: In a transmitting/receiving photonic IC made by laminating a flat light-emitting element 1 and a flat light-receiving element 2, such that an n-type semiconductor layer of one element of these elements abuts on a p-type semiconductor layer of the other element, the n-type semiconductor layer of the one element is connected to the p-type semiconductor layer of the other element in the IC with an electrode pattern 3 that is grounded and used at least in alternating current manner it. A crosstalk is prevented by grounding an interface layer between the element 2 and element 1 in a series constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission / reception photonic IC for optical communication having a light emitting portion and a light receiving portion in one element.

[0002]

2. Description of the Related Art As an introduction plan of an optical subscriber system is being advanced, one of the important factors for its widespread use is to reduce the price of a transmitter / receiver installed in each subscriber's house. The component that controls the price in the transceiver is an optical transceiver that performs optical-electrical conversion.

One of the methods for reducing the cost of the optical transmitting / receiving section is expected to be a semiconductor laser element (LD) as an optical / electrical conversion element and a photodiode (PD) as an electrical / optical conversion element. ), And a photonic IC (optical integrated circuit device) technology in which a wavelength filter, an optical waveguide, and the like for coupling them are formed on the same substrate by a series of processes.

Various structures have been proposed for photonic ICs. One of them is a structure in which a planar PD and a surface emitting laser element are vertically integrated as proposed in Japanese Patent Application Laid-Open No. Hei 6-37299. There are things. This example is shown in FIG.
Shown in

In the figure, reference numeral 101 denotes a wavelength of 1.31 [μ].
m], which is also a semiconductor laser device serving as a laser light oscillation source 1.3
The photodetector 102 detects light having a wavelength of [μm].
A photodetector that detects light having a wavelength of 55 [μm], 103 is an absorption layer that absorbs light in the 1.3 [μm] band, 105 is a non-reflective coating, and 106 is a 1.31 [μm] wavelength. An active layer for light oscillation and an absorption layer for detecting light having a wavelength of 1.3 μm, 107 is a photodetector 1 having a wavelength of 1.55 [μm].
An active layer 02 and a semiconductor substrate 110 are shown.

An electrode is formed on the first surface of the semiconductor substrate 110, an active layer 107 is formed on the second surface of the semiconductor substrate 110, and an absorption layer 103 is formed thereon to form a photodetector. A device (PD) 102 and a semiconductor laser element / photodetector 101 are formed thereon. The semiconductor laser element / photodetector 101 is composed of In formed on the absorption layer 103.
A GeAs layer, and a layer for forming a Bragg reflector thereon are further formed thereon, and an absorption layer and an active layer made of InGeAsP, and a layer for forming a Bragg reflector thereon, and an InP layer thereon. , A layer for forming a Bragg reflector thereon, and further thereon InGeA
This is a laminated structure in which an s layer, an anti-reflection coat 105 serving as a window on the uppermost layer, and an AuZnNi electrode surrounding the s layer are formed. As described above, in the photonic IC having the structure shown in FIG. 24, the surface emitting laser element is stacked on the planar PD.

[0007] In a structure in which surface-type elements as shown in FIG. 24 are vertically integrated, a connection point with an optical fiber which is an optical transmission line can be formed at one place, so that bidirectional transmission is performed with one optical fiber. Suitable for the system.

Meanwhile, one of the methods for coupling light from a laser element to an optical fiber is an optical coupling method called “butt coupling” in which a laser element and an optical fiber are simply opposed to each other without using lens coupling. is there. When this butt coupling is applied, usually, the mode field diameter of the laser is enlarged to approach the mode field diameter of the optical fiber so that good coupling efficiency can be obtained.

For this purpose, a general stripe type LD is used.
In the device, the spot size expansion region of the emitted laser beam is provided in the element. However, in the case of a surface emitting laser, the spot size can be easily brought close to the mode field diameter of the fiber depending on the size of the confinement region, so that the element structure can be simplified because there is no spot size expansion region.

In an element having a structure as shown in FIG.
Since PD and LD directly overlap in a layered manner,
Not only the crosstalk of light mentioned as a problem in Japanese Patent No. 37299, but also crosstalk due to electromagnetic coupling occurs.

Research on surface emitting laser elements has a short history, and little research has been made on the form of integration with light receiving elements into one IC device, and the problem remains unclear.

[0012]

Various IC elements for transmitting and receiving light, in which a laser element (LD) and a light receiving element (PD) are formed on the same substrate together with a filter, etc., have been proposed. A structure in which surface-emitting laser elements are vertically integrated is structurally simple and easily reduced in cost.

Therefore, a transmission / reception IC having this type of structure has been studied. However, as described above, in a structure in which a planar light-emitting element and a planar light-receiving element are stacked at the same position, it is structurally necessary to transmit light. Not only is crosstalk likely to occur, but there is also electromagnetic coupling, which inevitably results in the possibility of crosstalk, and measures are urgently needed.

Therefore, the object of the present invention is to
Transmit / receive photonic I which has no crosstalk, is easy to use, and has good characteristics.
C.

[0015]

Therefore, the present invention is configured as follows to achieve the above object.

That is, first, the present invention aims at suppressing crosstalk in a photonic IC for transmission and reception.
The flat type light emitting element and the flat type light receiving element are replaced with n of one element.
In a transmitting / receiving photonic IC in which the other element is stacked on one element such that the p-type layer (p-type semiconductor layer) of the other element is adjacent to the p-type layer (p-type semiconductor layer) of the other element, A transmitting and receiving photonic IC wherein the n-type layer of one element and the p-type layer of the other element are connected by an electrode pattern in the IC, and the electrode pattern is at least AC grounded. I will provide a.

In the present invention, as shown in FIG. 1, a light emitting element 1 and a light receiving element 2 are vertically stacked on a substrate. The basic type of the layer structure of the light-emitting element and the light-receiving element is a pin-like diode (a layer structure composed of a p-type layer-an intrinsic semiconductor layer (or a layer substantially regarded as an intrinsic semiconductor) -an n-type layer). However, in the present invention, the order of the layer configuration of the light emitting element and the light receiving element is the same (light emitting element: pin, light receiving element: pin, or light emitting element: nip, light receiving element). : Nip). By doing so, the n layer of the light emitting element and the p layer of the light receiving element
The layers are adjacent or the p-layer of the light-emitting element and the n-layer of the light-receiving element are adjacent. Adjacent p-layers and n-layers are connected by an electrode pattern in the photonic IC, and the connected electrodes are used by being electrically grounded.

The light emitting element normally applies a voltage having a polarity such that a forward bias is applied to the diode structure, and the light receiving element applies a voltage having a polarity such that the reverse bias is applied. Therefore, when the adjacent p-type layer and n-type layer are connected by an electrode pattern and used as ground as described above, the positive and negative voltages applied to the light emitting element and the light receiving element become the same. As a result, only one of the positive and negative power supply voltages of the circuit for driving the element is required, and the electronic circuit configuration can be simplified.

Further, as in the present invention, by using the layer at the boundary between adjacent elements with ground, the grounded layer acts as an electromagnetic shield surface. Therefore, the light emitting surface,
Crosstalk between transmission and reception due to electromagnetic coupling between the light emitting element and the light receiving element through the light receiving surface is eliminated, and the receiving sensitivity of the element is improved.

Second, the present invention is characterized in that, in order to suppress crosstalk, in the configuration of the first invention, the IC is formed on an insulating substrate or a semi-insulating substrate.

In the integrated device as described above, the bonding electrode pads are formed on the substrate (FIG. 4). When the substrate is n-type or p-type, the substrate 14 and the electrode pad 2
In order to take insulation between the dielectric layers 6, a dielectric layer 24 is interposed therebetween.

With such a configuration, a parasitic capacitance occurs between the substrate and the electrode pad. If the substrate is a ground plane, the original capacitance component of the element will only increase slightly. However, in the present invention, what is grounded is the layers 11 and 12 in contact with the light emitting element and the light receiving element, and not the substrate.

Therefore, when the substrate is n-type or p-type, the electrode pad 26 extending from the electrode 4 attached to the layer 9 of the element 1 stacked on the side not in contact with the element below and the substrate 14 Are parasitic capacitances as indicated by 65 in FIG.

This is a capacitance for coupling between the light emitting element and the light receiving element, and causes crosstalk. Therefore, as a method for preventing such a parasitic capacitance from occurring in the embodiment of the present invention, a light emitting element and a light receiving element are formed on a semi-insulating substrate.

As a result, it is possible to eliminate crosstalk caused by the above-mentioned causes.

Thirdly, the present invention relates to a technique for stabilizing the oscillation operation of a light emitting device, in which a planar light emitting device is stacked on a semiconductor substrate, and the planar light emitting device is mounted on the flat light emitting device. In a transmission / reception photonic IC in which planar light receiving elements having an absorption edge wavelength longer than an oscillation wavelength are stacked, a Bragg mirror layer above an active layer of the planar light emitting element and the active layer via the Bragg mirror layer A transmission / reception photonic, wherein an absorption layer having an absorption end wavelength between the oscillation wavelength and the absorption end wavelength of the planar light receiving element is provided between electrodes for passing a current through the transmission / reception photonic. Provide IC.

When a light receiving element is stacked on a light emitting element as shown in FIG. 11, the uppermost layer 46 of the light emitting element has a region where the light receiving element 2 is stacked on top, a region where the electrode 48 is stacked, and Other regions (often a dielectric passivation film is laminated). When the light emitting element is a laser element, the uppermost layer is provided with a reflecting mirror such as a Bragg mirror formed by alternately laminating thin layers having different refractive indexes.

However, in order to make a Bragg mirror have a reflectance of 100% in a planar light emitting type semiconductor laser device used in the present invention, it is necessary to stack a very large number of layers. No. This is effectively
It is difficult and it is not usual to form a mirror layer until the reflectance of 100% can be secured. Therefore, the laser light is not completely reflected by the mirror layer, and a part thereof leaks out of the mirror layer.

In the structure as shown in FIG. 11, the leaked light reaches the interface 51 which is the boundary between the light emitting element and the light receiving element. As described above, a part of the interface 51 is in contact with the light receiving element. , Some are in contact with the outside. Therefore, the reflectance at the interface 51 differs depending on the portion, and the ratio of light reflected at the interface 51 and returning to the active region differs in the plane of the light emitting element. In such a state, efficient and stable oscillation as a laser element cannot be obtained.

In order to prevent this, a layer for absorbing light having the oscillation wavelength of the light emitting element is provided between the Bragg mirror layer and the interface 51. As a result, the laser light not reflected by the Bragg mirror layer is absorbed on the way by this absorption layer and
Will not reach.

Accordingly, no light is reflected at the interface 51 and returns to the active layer, and the oscillation state of the laser element is not affected by the variation of the reflected light from the interface 51.

Fourth, the present invention relates to a transmission / reception photonic IC in which one of a planar light emitting element and a planar light receiving element is stacked on top of the other, and the electrode of the light receiving element is provided. The power distribution of the output light of the light emitting element on the end face not adjacent to the light emitting element,
It is characterized in that the peak is formed outside a region of 1 / e ² (e is the base of natural logarithm) or more. That is, from the peak of the power distribution of the output light of the light emitting element on the end surface of the light receiving element that is not adjacent to the light emitting element to the portion where the power becomes 1 / e ² (e is the natural logarithm base) of the peak. There is no metal electrode of the light receiving element in the region.

In the third aspect of the invention, in order to suppress reflection at the interface between the light receiving element and the light emitting element, the light emitting element wavelength absorption layer is provided on the light emitting element side from the interface. However, when “wavelength of light emitting element”> “wavelength of light receiving element”, as shown in FIG. 16A, there is a light receiving element closer to the optical fiber to be coupled, and light from the light emitting element passes through the light receiving element. Output to the optical fiber. If the bandgap wavelength of the light receiving element is shorter than the wavelength of the light emitting element, the light receiving element has no sensitivity to the wavelength of the light emitting element and does not cause crosstalk.

In such a wavelength relationship, if the order of the light emitting element and the light receiving element is reversed, the light emitting element absorbs the light to be received by the light receiving element, and the light cannot be received. Therefore,
The absorbing layer cannot be sandwiched as in the third invention.

When the light-emitting element is a laser, the Bragg mirror on the output side of the light-emitting element has a slightly lower reflectivity to extract output light. In the example of the present invention, light output from the light emitting element is radiated outside the element via the light receiving element. An end face 67 of the light receiving element that is not adjacent to the light emitting element is provided with a ring-shaped metal electrode 68 for applying a voltage to the light receiving element. The output light of the light emitting element reflected by the end face 67 returns to the active layer of the light emitting element via a Bragg mirror designed to have a lower reflectance. If the reflectance of the end face 67 where the light from the light emitting element shines is not uniform in the plane, the ratio of the light returning to the active layer becomes non-uniform in the effective area of the active layer. As a result, there is a possibility that the output of the light emitting element becomes unstable with low efficiency.

In order to avoid such a problem, according to the present invention, the light output from the light emitting element is applied to the end face 67 of the light receiving element.
In order to make the reflectivity of the end face 67 uniform in a region corresponding to the above, a metal electrode is arranged outside the region. Although it is difficult to define the area where the light output from the light emitting element hits, the diameter of the light beam is generally 1 / e ² of its peak power.
It is often expressed by the diameter of the part that becomes Further, in a Gaussian beam generally approximated as the shape of a light beam, most of the light power (> 86%) is included from the peak to 1 / e ² .

Further, the light output from the light emitting element spreads as it propagates. Accordingly, the light toward the end of the beam is reflected at an angle slightly deviated from the perpendicular to the end face 67, and as shown in FIG. 16B, the reflected light returns outside the effective active region of the light emitting element. . Therefore, it is not necessary that the reflectance of the end face 67 is uniform over the entire area of the beam, and an uneven portion may be present at the end. As a guide, we focused on the region up to 1 / e ² described above.

Fifth, in order to enhance the effect of the fourth aspect of the present invention, the area is coated with a substantially uniform anti-reflection coating, and the wavelength band corresponding to the anti-reflection coating is equal to that of the light emitting element. It is characterized in that it includes the emission wavelength and the light reception wavelength of the light receiving element.

Even in the form of the fourth aspect, the reflected light returning from the end face 67 to the effective active region of the light emitting element is not eliminated. In order to stabilize the oscillation of the laser, it is better that the amount of reflected return light is small. Therefore, a uniform non-reflective coating is applied to the area where 1 / e ² is used.

When a non-reflective coating 57 is applied to the region inside the electrode 68 as shown in FIG. 14, the boundary between the electrode 68 and the electrode is coated so as to be slightly disturbed. Therefore, the aforementioned 1 / e
It is desirable that the region of ² does not include such a boundary portion. Further, it is desirable that the effective wavelength region of the antireflection coat includes the emission wavelength of the light emitting element and the wavelength received by the light receiving element.

Sixth, the present invention is a transmission / reception photonic IC in which a planar light-receiving element is stacked on a planar light-emitting element, wherein the light-emitting element has an effective active area limited by a structure such as a current block. The light receiving element is formed above the limited effective active area, and the effective light receiving area in the light receiving layer of the light receiving element is assumed that the output light of the light emitting element reaches the light receiving layer. In this case, the position and the area are set so as to occupy a range of 95% or more of the total power of the output light reaching the plane including the light receiving layer.

The IC of the present invention is generally used by being coupled to a single mode fiber. Laser element and optical fiber,
In “bat coupling” in which optical coupling is performed without using a lens, it is necessary to design the output beam diameter of the light emitting element to be close to the mode field diameter of the optical fiber in order to increase coupling efficiency. In the structure in which the light receiving element is stacked on the light emitting element as shown in FIG. 17 (a), if the element size and the electrode size are designed so that the beam diameter of the light emitting element approaches the mode diameter of the fiber, the light emitting element is stacked on the upper part. The size of the light receiving element is smaller than the mode diameter of the fiber.
Only a part of the light incident from the optical fiber can be received, and the light receiving efficiency deteriorates. In order to obtain sufficient light receiving efficiency, the light receiving diameter should be larger than the mode diameter of the fiber. In that case,
Since the electrode 48 of the light emitting element is outside the light emitting element region,
In a configuration in which the beam diameter of the light emitting element is determined in a region determined by the electrode 48, the beam diameter of the light emitting element becomes larger than the mode diameter of the fiber.

In order to avoid such a dilemma, in the present invention, as shown in FIG. 17B, for example, a current confinement layer is provided inside the light emitting element to limit the effective beam diameter to about the mode diameter of the fiber. The layer 60 in contact with the uppermost metal electrode on the top of the light emitting element is larger than the limited beam diameter, and the metal electrode 48 is similarly laminated with a larger diameter. A light receiving element having a sufficient light receiving diameter may be stacked thereon.

Strictly, the light receiving element receives the light output from the optical fiber. Therefore, it seems at first glance that the effective light receiving diameter is defined with respect to the beam spread of the light emitting element as in the present invention. However, in practice, both the beam diameter of the light emitting element and the effective light receiving diameter of the light receiving element are shown in FIG.
It is determined with respect to the beam diameter and the spread of the optical fiber arranged very close as shown in FIG.
The optical fibers are very close and the thickness of the device area of the IC is very small. Therefore, if the beam diameter of the light emitting element is close to the mode diameter of the fiber, the shape of the beam from the optical fiber in the light receiving layer of the light receiving element can be considered to be substantially the same as the shape of the beam of the light emitting element.

Accordingly, the sixth aspect of the present invention is not irrelevant and is technically extremely reasonable.

It should be noted that a value of 95% means a loss from 100% to about 0.2 dB, which is generally a value that can be tolerated without problems in an optical communication system, and is a design boundary. The value is a meaningful number.

Seventh, according to the present invention, one of a light emitting element having a pin structure and a light receiving element having a pin structure is stacked on a substrate, and the other of the light emitting element and the other is extended on the uppermost layer of the one element or on the extension of the uppermost layer. The elements are stacked so that the impurity type of the lowermost layer of the other element is different from the impurity type of the uppermost layer of the one element, and the uppermost layer or the extension of the uppermost layer of the one element and the extension of the other element. A transmission / reception photonic IC wherein the lowermost layer or an extension of the lowermost layer is connected by a metal electrode pattern, and the electrode pattern is used by being grounded at least in an AC manner.

This is a modification of the first invention, and corresponds to not only a planar light emitting element and a light receiving element but also a stripe light emitting element and a light receiving element. As shown in FIG. 22A, in a photonic IC of a type in which a stripe type light emitting element and a light receiving element are coupled by an optical waveguide, FIG.
As shown in the cross-sectional view taken along the line AA ′ in FIG. At this time, the light emitting element is not on the effective area of the light receiving element. However, the uppermost layer 12 of the light receiving element extends below the light emitting element, and the light emitting element is stacked thereon. The lowermost layer 11 of the light emitting element and the uppermost layer 12 of the light receiving element are connected by the metal electrode 3. At this time, if the uppermost layer of the light-receiving element is n-type, the light-emitting element is laminated so that the lowermost layer is p-type. If the uppermost layer of the light-receiving element is p-type, the lowermost layer of the light-emitting element is n-type. Are laminated as follows.
When the metal electrode 3 is grounded, the polarity of the drive voltage power supply for the light emitting element and the light receiving element can be made the same, and crosstalk due to electromagnetic coupling between the elements can be prevented.

[0049]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) [Basic Structure of Transmit / Receive Photonic IC] In the first embodiment, the IC structure is as follows. That is, a planar light emitting element (LD) and a planar light receiving element (PD)
In a transmission / reception photonic IC in which the other element is stacked on one element such that the n-type layer of one element and the p-type layer of the other element are adjacent to each other, An n-type layer of the element and a p-type layer of the other element are connected by an electrode pattern in the IC, and this electrode pattern is configured to be grounded at least in an AC manner.

In the embodiment shown here, for example, FIG.
As shown in (a), the planar light receiving element 2 is placed on the substrate 14.
Is formed, and the planar light emitting element 1 is laminated on the light receiving element 2.

That is, in the configuration of FIG. 1A, an intrinsic semiconductor layer 13 is formed on an n-type semiconductor substrate 14, and a p-type semiconductor layer 12 is formed on the intrinsic semiconductor layer 13. The light receiving element 2 is formed by the “substrate 14 -the intrinsic semiconductor layer 13 -the p-type semiconductor layer 12”. Then, the p-type semiconductor layer 12
An n-type semiconductor layer 11 is formed on the n-type semiconductor layer 11.
An intrinsic semiconductor layer 10 is formed thereon, and a p-type semiconductor layer 9 is further formed on the intrinsic semiconductor layer 11. A light emitting element is formed by the "n-type semiconductor layer 11-the intrinsic semiconductor layer 10-the p-type semiconductor layer 9". Form one. An electrode pattern 3 is formed on the side circumference of the n-type semiconductor layer 11 of the light-emitting element 1 and on the surface of the p-type semiconductor layer 12 of the light-receiving element 2 adjacent thereto. Ground electrode.

Note that the category of the “intrinsic semiconductor layer” described above and thereafter includes a case where the semiconductor layer contains a trace amount of impurities that can be regarded as substantially intrinsic.

Assuming that the light emitting element 1 and the light receiving element 2 are formed by laminating, for example, in a circular shape, the result is as shown in FIG. That is, in FIG. 1B, a circular intrinsic semiconductor layer 13 is formed on an n-type semiconductor substrate 14, and a circular p-type semiconductor layer 12 is formed on the intrinsic semiconductor layer 13. This “substrate 14-intrinsic semiconductor layer 13-p-type semiconductor layer 12”
To form the light receiving element 2. Then, a circular n-type semiconductor layer 11 having a diameter slightly smaller than the diameter of the p-type semiconductor layer 12 is formed concentrically on the circular p-type semiconductor layer 12, and the n-type semiconductor layer 11 is formed on the n-type semiconductor layer 11. A circular intrinsic semiconductor layer 10 having a diameter somewhat smaller than that of the semiconductor layer 11 is formed concentrically, and a circular p-type semiconductor layer 9 is formed on the intrinsic semiconductor layer 11. The light emitting element 1 is formed from the 10-p type semiconductor layer 9 ″. An electrode pattern 3 is formed on the side circumference of the n-type semiconductor layer 11 of the light-emitting element 1 and on the surface of the p-type semiconductor layer 12 of the light-receiving element 2 adjacent thereto. Ground electrode.

As described above, the present invention has a structure in which the light emitting element 1 and the light receiving element 2 are vertically stacked on the substrate 14 and the joint boundary position between the light emitting element 1 and the light receiving element 2 is grounded.

The basic structure of the light emitting element 1 and the light receiving element 2 is a diode having a pin (p-type semiconductor layer-intrinsic semiconductor layer-n-type semiconductor layer) structure. Is characterized in that the order of the layer configuration of the light emitting element 1 and the light receiving element 2 is the same.

That is, the light emitting element 1 is a “p-type layer-i-type layer-n-type layer”, and the light receiving element 2 is a “p-type layer-i-type layer-
The light emitting device 1 may have a layer structure of “n-type layer” or “n-type layer-i-type layer-p-type layer”, and the light receiving device 2 may have a “n-type layer-i-type layer-p-type layer”. It has a layer structure.

With this arrangement, the arrangement structure is such that the n-type layer of the light-emitting element 1 is adjacent to the p-type layer of the light-receiving element 2, or the p-type layer of the light-emitting element 1 is adjacent to the n-type layer of the light-receiving element 2. . Adjacent p-type and n-type layers are connected by an electrode pattern 3 in the photonic IC, and the connected electrode 3 is used by being electrically grounded.

The light emitting element 1 normally applies a voltage having a polarity such that a forward bias is applied to the diode structure, and the light receiving element 2 applies a voltage having a polarity such that the reverse bias is applied. Therefore, when the adjacent p-type layer and n-type layer are connected by the electrode pattern 3 as described above and this electrode pattern 3 is used by grounding, the positive and negative voltages applied to the light emitting element 1 and the light receiving element 2 are the same. become. As a result, the power supply voltage of the circuit for driving the elements can be either positive or negative, that is, only a single DC power supply can be used, and the electronic circuit configuration can be simplified.

Further, as in the present invention, the layer at the boundary between adjacent elements is grounded and used, so that the grounded layer (the p-type semiconductor layer 12 and the n-type semiconductor layer 1 in the configuration of FIG. 1) are used.
1) acts as an electromagnetic shield surface. Therefore, crosstalk between transmission and reception due to electromagnetic coupling between the light emitting element and the light receiving element through the light emitting surface and the light receiving surface is eliminated, and the receiving sensitivity of the element is improved.

[Modification 1] FIG. 2A is a modification of the photonic IC having the above-described basic structure. This photonic IC is formed on a light receiving element 2 formed by stacking an n-type layer (n-type semiconductor layer) 14, an i-type layer (intrinsic semiconductor layer) 13, and a p-type layer (p-type semiconductor layer) 12 in this order. The light emitting element 1 is also formed by stacking the n-type layer 11, the i-type layer 10, and the p-type layer 9 in this order from the bottom.

Further, a metal electrode 3 for electrically connecting the p-type layer 12 of the light-receiving element 2 and the n-type layer 11 of the light-emitting element 1 is formed on the exposed surface of the p-type layer 12 and the n-type layer 11. Is formed on the exposed surface. That is, the p-type layer 1
2, the n-type layer 11 is formed with a smaller area than the p-type layer 12, and the intrinsic semiconductor layer 10 on the n-type layer 11 is
By forming it with a smaller area, each exposed surface is secured in the p-type layer 12 and the n-type layer 11, and the metal electrode 3 is formed using the exposed surfaces. This electrode 3 is grounded when using an IC. 4 is p
A metal electrode for a light emitting element formed on the mold layer 9;
Is a metal electrode for a light-receiving element formed on the back side of FIG.

If a metal electrode is normally provided on the semiconductor layer, the contact portion has diode characteristics. This is luminescence,
This is a problem because it has a great effect on the light receiving characteristics. It is necessary to make ohmic contact to have no diode characteristics.

The components of the metal electrode for making ohmic contact are different between the case where an electrode is provided on the p-type layer and the case where the electrode is provided on the n-type layer. Therefore, the electrodes of the n-type layer and the p-type layer cannot be applied at once.

Therefore, as shown in FIG. 2B, separate electrodes 6 and 7 are attached to the respective layers so that a part thereof is overlapped. In the example of FIG. 2B, the metal electrode 7 for the p-type layer is formed on the exposed surface of the p-type layer 12, and then the metal electrode 7 partially overlaps the surface of the metal electrode 7 so that n The metal electrode 6 is formed on the exposed surface of the mold layer 11. This part of the overlapping portion serves as an electrical connection between the electrodes 6 and 7.

Alternatively, as another structure of the electrode 3, FIG.
As shown in (c), separate electrodes 6 and 7 are applied to each of the layers 12 and 11, and then another electrode 8 is further applied.
And the electrodes 6 and 7 are connected. In this case, the formation position of the electrode 8 connecting the two electrodes 6 and 7 is shown in FIG.
It is not always necessary to be on the element region as in (c), but it may be formed on a bonding pad or a wiring part on the way from the element region to the bonding pad.

Although not widely used at present, there is a method of making ohmic contact, which does not rely on a p-type layer or an n-type layer, but roughens the surface of a semiconductor layer. Using such a method, the layers may be formed in a single layer as shown in FIG.

Layer 11 of light emitting element 1 and layer 12 of light receiving element 2
When the light emitting element 1 and the light receiving element 2 have a circular structure, the electrode pattern for connecting
The electrodes 6 and 7 are separated concentric rings having different diameters, and a portion connecting the electrodes 6 and 7 is shown in FIG.
As shown in FIG. 3A, a structure having only one location may be used. However, if more importance is placed on the stability as an electromagnetic shield, the entire surface should be continuous as shown in FIG. 3B. Alternatively, as shown in FIG. 3C, it is preferable that the connection is made at a plurality of locations. In FIG. 3, FIG.
It is assumed that the electrode connection method shown in FIG.

In FIG. 2A, an n-type layer, an i-type layer, and a p-type layer are stacked in this order from the bottom. However, as shown in FIG. , I-type layer 22, n-type layer 2
1, a p-type layer 20, an i-type layer 19, and an n-type layer 18 may be stacked in this order.

As described above, according to the invention shown in the first embodiment, the light emitting element and the light receiving element are arranged in the order of layer arrangement (n-type layer,
The order of the i-type layer and the p-type layer) is the same, and the light-emitting element and the light-receiving element are connected to an electrode at a layer located at the boundary between the two, and are used by grounding this electrode.

By doing so, the polarity of the voltage applied to the light emitting element and the polarity of the voltage applied to the light receiving element become the same. As a result, the peripheral circuit is simplified and the cost is reduced. Either the light-emitting element or the light-receiving element stacked in the IC may be on the substrate side, and the vertical relationship may be either. However, which one comes to the optical fiber side differs depending on the relationship between the emission wavelength and the reception wavelength.

In recent years, there is a method called flip-chip mounting, in which a chip is mounted on a submount with the upper surface of the chip facing down. Therefore, the vertical relationship inside the chip is arbitrary. Further, the light emitting element may be a light emitting diode or a surface emitting laser element. However, when a laser element is used, a resonator structure is required.

In the case of a laser device, a Bragg mirror in which layers having different refractive indices are alternately stacked in a p-layer and an n-layer above and below an active layer is provided for this purpose. The upper and lower Bragg mirrors are used as laser resonators.

Although not particularly shown or described in the present specification, when the light emitting element is a laser element, such elements for forming a resonator are naturally included.

By the way, wires are bonded to the electrodes 3 and 4 of the light emitting element 1 and the light receiving element 2 in order to lead the wiring to the outside of the IC. As shown in FIG. The electrode pads 25 and 26 are formed on the substrate 14. Therefore, the metal wiring layers 25a and 26a are formed from the electrode 4 along the peripheral side surfaces of the light emitting element and the light receiving element, and from the electrode 3 along the peripheral side surface of the light receiving element (both of FIG. 1). In the case where the configuration is taken as an example), it is connected to the corresponding electrode pads 25 and 26 on the substrate 14.

In the photonic IC of the present invention, the dielectric layer 2 is used to insulate the substrate 14 from the electrode pads 25 and 26 and to insulate the light emitting element and the light receiving element.
4 are formed so as to be sandwiched therebetween. The presence of the dielectric layer 24 forms a capacitance (capacitor) between the substrate 14 and the electrode pads 25 and 26.

However, as in the case of the present invention, the layer at the element boundary between the light receiving element and the light emitting element to be laminated is grounded and the substrate is used without being grounded. When the substrate is n-type or p-type, the capacitance between the electrode 26 and the substrate 14 is as shown at 65 in FIG. This causes crosstalk. Further, as shown in FIG. 4B, when the light receiving element 2 is stacked on the substrate 14 side, the light receiving element structure is not a mesa type but a planar type in which the uppermost layer is formed by diffusion. In some cases.

That is, the intrinsic semiconductor layer 28 is formed on the substrate 14.
Is formed, and p is diffused into a part of the intrinsic semiconductor layer 28 by diffusion.
The mold layer 27 is formed.

In such a case, the electrodes 25 and 26 are formed on the surface 29 of the intrinsic semiconductor layer 28 via the dielectric layer 24. In this case, similarly, a capacitance is generated between the electrode 26 and the substrate 14, which causes crosstalk. This is a problem peculiar to the structure having the basic structure of the first embodiment and grounding the layer at the boundary position between the stacked elements.

That is, a normal surface light emitting element or light receiving element alone does not handle two or more types of signals in the same element.
Parasitic capacitance does not cause crosstalk even if the response speed of the element is slightly deteriorated. Further, a structure in which the light emitting element and the light receiving element are vertically integrated as in the present invention (that is,
Even in the case of the stacked arrangement structure), there is no problem if the substrate is grounded. Therefore, this problem is unique to the configuration of the first embodiment in which the substrate is not used as a ground plane.

To solve this problem, the following measures may be taken. That is, as shown in FIG. 6, the substrate 14 is a semi-insulating substrate 31. Then, an n-type semiconductor layer 30 is formed on the semi-insulating substrate 31, and an intrinsic semiconductor layer 13 and a p-type semiconductor layer 12 are formed on the n-type semiconductor layer 30. The n-type semiconductor layer 30, the intrinsic semiconductor layer 13, and the p-type The light receiving element 2 is formed by the semiconductor layer 12, and the p-type semiconductor layer 12
The n-type semiconductor layer 11, the intrinsic semiconductor layer 10, and the p-type semiconductor layer 9 are stacked and formed in this order on the light emitting element 1.

Here, the semi-insulating substrate refers to a semiconductor substrate having a high resistance. Note that any device may be used as long as the elements can be laminated or bonded on a completely insulating substrate instead of a semi-insulating substrate.

In the structure of FIG. 6, the uppermost p-type semiconductor layer 9
The metal wiring layer 26a is formed by extending the peripheral surface of the light emitting element 1 and the light receiving element 2 from the electrode 4 formed thereon, and the peripheral surface of the light receiving element 2 is extended by the electrode 3 for grounding. A metal wiring layer 25a which is not formed is formed (in the case of taking the basic configuration of FIG. 1 as an example) and connected to the corresponding electrode pads 25 and 26 formed on the surface of the semi-insulating substrate 31. The metal wiring layers 25a and 26a are insulated from the light emitting element 1 and the light receiving element 2 via the dielectric layer 24.

Further, a metal electrode 32 is formed on the n-type semiconductor layer 30 of the light receiving element 2 as a counter electrode of the light receiving element 2 in contact with the n-type semiconductor layer 30, and the metal electrode 32 is formed on the semi-insulating substrate 31. Is connected to the bonding electrode pad 33 formed on the substrate. Reference numeral 34 denotes a metal electrode formed on the non-element forming surface side of the semi-insulating substrate 31.

Here, the bonding electrode pads 26,
25 and 33 are arranged opposite to the metal electrode 34 via the semi-insulating substrate 31, so that when the metal electrode 34 is not grounded,
The parasitic capacitances 35 and 36 are formed between them. This is equivalently shown in FIG. 7, which causes crosstalk. Therefore, this parasitic capacitance is reduced to 35,3
6 must be eliminated. In the present invention, the problem of the parasitic capacitance is solved by using a configuration in which the metal electrode 34 is grounded.

In this manner, it is possible to prevent the capacitance from being generated between the elements by the electrode pad, and to eliminate one of the causes of the crosstalk. The wiring 35 on the way from the electrode provided on the layer to the bonding electrode pad traverses over the other layer (30), and a capacitance is generated at the crossing portion. The capacity is small and there is no problem.

The bonding electrode pad connected to the ground electrode 3 is not shown for convenience of drawing, but is still present on the substrate 31. Although a metal wiring layer connecting the electrode 3 and the bonding electrode pad is omitted in the drawing, it actually exists.

In the above description, when the substrate is not grounded,
A photonic IC without crosstalk is formed by using a semi-insulating substrate and stacking a light-receiving element and a light-emitting element on this semi-insulating substrate in order to eliminate the capacitance component that may be formed at the electrode pad part. An example was shown in which it was obtained.

However, there are cases where it is desired to form a photonic IC using an n-type or p-type substrate instead of a semi-insulating substrate.

In such a case, the electrode pad 26 which is not used for ground (ground) and which is not a substrate, as shown in FIG.
This can be realized by forming a ground electrode 37 thereon.

That is, the dielectric layer 24a is formed on the substrate 14 at the position where the electrode pad 26 is to be formed. The dielectric layer 24a is further extended and formed over a section reaching the layers 13 and 12, which are the elements forming the light receiving element 2, and a metal wiring layer 37 is formed on the dielectric layer 24a. To form a ground electrode (ground electrode). The ground electrode formed by the metal wiring layer 37 is disposed so as to extend to the position of the electrode 3, the corresponding portion of the electrode 3 is connected to the electrode 3,
The electrode 3 and the ground electrode are kept at the ground potential by grounding.

Then, the dielectric layer 24 is laminated on the ground electrode formed by the metal wiring layer 37, and the dielectric layer 24 is formed over the upper end of the side surface of the layer 9 via the layer 10.
Then, on the dielectric layer 24, an electrode pad 26 and a metal wiring layer 26a connecting the electrode pad 26 to the electrode 4 are formed.

In this way, since the capacitance formed by the metal wiring layer 26a and the electrode pad 26 is a capacitance with respect to the ground, it does not cause crosstalk.

For use in flip-chip mounting, as shown in FIG. 9, a bonding electrode pad 25PAD connected to the ground around the element on the substrate 14 and an electrode lead wire on the counter electrode side of the light receiving element 2 are formed. Bonding electrode pads 40PAD are formed on flip-chip pedestals 41 formed on the substrate 14, respectively, and required wirings are provided by metal wiring layers.

A counter electrode 4 for the light emitting element 1 is formed on the uppermost layer 9, and a bonding electrode pad 38 PAD is formed on the layer 9 so as to be connected to the electrode 4. Electrode pad 25PA
D, 38 PAD, and 40 PAD are aligned so that their heights are substantially equal. Then, these bonding electrode pads 25PAD, 38PAD, and 40PAD are directly mounted on a mounting board by soldering or the like.

In this case, if the electrode pads 38PAD are prevented from protruding from above the layer 9, the capacitance which has been a problem so far is not formed. It is the middle layer 1
This is because 1 and 12 are at the ground, and the capacitance is formed between the ground and the ground layer.

The photonic IC of the present invention has mainly been described with a structure in which a planar light emitting element and a planar light receiving element are stacked. In the case of such a photonic IC having a laminated structure of planar optical elements, an optical fiber for transmitting an optical signal is coupled to the optical element on the IC. That is,
The tip of the optical fiber is opposed to the surface of the IC, and optical coupling is performed by aligning the optical axis of the optical element with the optical axis of the optical fiber.
In the case of a flip chip, the optical fiber faces the back side of the IC and is optically coupled.

However, as described above, the arrangement order of the light emitting element and the light receiving element viewed from the optical fiber is determined by their wavelength relationship.
Some are not suitable for a configuration in which C is used as a flip chip and coupled to an optical fiber on the substrate side.

That is, if the wavelength of the light emitting element> the wavelength of the light receiving element, the light emitting element absorbs the wavelength to be received by the light receiving element, so that a fiber must be connected to the light receiving element side. At this time, since the light receiving element has no sensitivity to the wavelength of the light emitting element and transmits the light, the light emitting element and the optical fiber can be coupled via the light receiving element.

On the other hand, the wavelength of the light emitting element <the wavelength of the light receiving element
In the case of (1), since the light receiving element absorbs light of the wavelength of the light emitting element, the optical fiber needs to come to the light emitting element side. At this time, since the light emitting element transmits the wavelength to be received by the light receiving element, coupling between the light receiving element and the optical fiber can be performed via the light emitting element.

In this case, the light leaked from the light emitting element is input to the light receiving element and causes crosstalk. However, the wavelength of the light emitting element is absorbed between the light emitting element and the light transmitted by the light receiving element. The problem is solved by sandwiching layers.

As described above, since the arrangement order of the light emitting element and the light receiving element viewed from the optical fiber is determined by their wavelength relationship, depending on the configuration, the photonic IC is flip-chip and the photonic IC substrate is connected to the optical fiber. Some configurations are not suitable for coupling, that is, a configuration for coupling to an optical fiber on the back side of the substrate of a photonic IC.

In such a case, it is necessary to couple with the optical fiber from the element surface side on the IC substrate. For example, a submount 42 having a through hole 42a as shown in FIG. The optical element portion is located at the position of the through-hole 42a, and is flip-chip mounted on one surface of the submount 42 as shown in the figure. Then, the tip of the optical fiber 45 is inserted into the through hole 42a from the other surface of the submount 42 and fixed.

In this way, a structure can be obtained in which the optical element surface is optically coupled to the optical fiber.

As described above, it is possible to cope with the case where the optical fiber 45 is coupled from the upper surface of the chip (the upper surface of the IC (element forming surface)).

Furthermore, in these ICs, it cannot be said that there is no possibility that crosstalk will occur due to electromagnetic coupling via the space between the electrode pads. In order to reduce such crosstalk, it is preferable that the electrode pads other than the ground electrode of the light emitting element and the light receiving element are arranged as far as possible, for example, by being arranged on the opposite side across the element region. At this time, arranging the ground electrode so as to come between them has a high effect of reducing electromagnetic coupling.

As described above, the first embodiment is a photonic IC in which a planar light emitting element and a planar light receiving element are stacked and formed on a substrate, and the planar light emitting element and the planar light receiving element are: A transmitting / receiving photonic IC in which the other element is stacked on one element so that the n-type layer (n-type semiconductor layer) of one element is adjacent to the p-type layer (p-type semiconductor layer) of the other element Wherein the n-type layer of one of the adjacent elements and the p-type layer of the other element are connected by an electrode pattern in the IC, and the electrode pattern is at least AC grounded. It is. Further, the light emitting element and the light receiving element are formed on a semi-insulating substrate.

When the layer at the boundary between adjacent elements is grounded and used as in the present invention, the grounded layer acts as an electromagnetic shield surface, so that light emission through the light emitting surface and the light receiving surface is performed. Crosstalk between transmission and reception due to electromagnetic coupling between the element and the light receiving element is eliminated, and the receiving sensitivity of the element is improved. When the substrate is n-type or p-type, the capacitance between the substrate and the electrode pad, which is an extension of the electrode attached to the layer which is not in contact with the lower device, is a parasitic capacitance. This is a capacitance that couples the light emitting element and the light receiving element, and causes crosstalk. However, as a method of not generating such parasitic capacitance, the light emitting element and the light receiving element are formed on a semi-insulating substrate, so that the crosstalk caused by the parasitic capacitance can be eliminated. is there.

As described above, the first embodiment is a technique for suppressing the influence of crosstalk due to the formation of a capacitance component by an electrode pad or the like in a photonic IC.

Incidentally, in photonic ICs, a laser element is often used as a light emitting element. When the planar light emitting element and the planar light receiving element are stacked and arranged, an unstable operation of laser oscillation due to a reflection component at a boundary surface may be a problem. Therefore, a technique for avoiding the unstable operation of laser oscillation will be described next.

(Second Embodiment) [Part 1] The invention described here is a technique for stabilizing the oscillating operation of a light emitting element, and comprises stacking a planar light emitting element on a semiconductor substrate. In a transmission / reception photonic IC in which a planar light receiving element having an absorption edge wavelength longer than the oscillation wavelength of the planar light emitting element is stacked on the planar light emitting element, a Bragg mirror layer above an active layer of the planar light emitting element is provided. An absorption layer having an absorption edge wavelength between the oscillation wavelength and the absorption edge wavelength of the planar light receiving element is provided between electrodes for passing a current to the active layer via the Bragg mirror layer. It is characterized by having a configuration that
Hereinafter, the details will be described. In this example, a laser element is assumed as a light emitting element, and the oscillation laser light of the laser element transmits through the Bragg mirror layer used in the case of the laser element and is reflected at the boundary surface with the light receiving element, and this returns to the laser element A photonic IC that can suppress the influence of the photonic will be described.

As shown in FIG. 12, in a photonic IC having a structure in which a light-emitting element 1 is formed on a substrate and a light-receiving element 2 is formed thereon, the interface between the light-emitting element 1 and the light-receiving element 2 is changed. Optically non-uniform.

That is, in the case of the structure in which the planar light-receiving element 2 is laminated on the planar light-emitting element 1 as shown in FIG. 11, the uppermost layer 46 of the light-emitting element 1 has a region on which the light-receiving element 2 is laminated. And a region where the electrode 48 is laminated, and a region other than the region (often a dielectric passivation film is laminated).

When the light-emitting element 1 is a laser element, the uppermost layer is provided with a reflecting mirror (mirror layer) such as a Bragg mirror formed by alternately stacking thin layers having different refractive indexes.

However, in order to provide a Bragg mirror with 100% reflectivity in a planar light emitting type semiconductor laser device used in the present invention, it is necessary to stack a large number of layers. No. This is effectively
It is difficult and it is not usual to form a mirror layer until the reflectance of 100% can be secured.

Therefore, the laser beam is not completely reflected by the mirror layer, and a part of the laser beam passes through the mirror layer and leaks out of the mirror layer.

In the planar device structure as shown in FIG. 11 in which the light emitting element 1 is formed on the substrate side and the light receiving element 2 is laminated thereon, the area occupied by the light emitting element 1 is naturally larger than that of the light receiving element 2. It is larger than the area occupied by the element 2. Therefore, the interface 51 which is a boundary surface between the light emitting element 1 and the light receiving element 2
Is partially in contact with the light receiving element 2 and partially in contact with the outside.

Therefore, the reflectance at the interface 51 differs depending on the portion, and the light emitted from the light-emitting element 1 and leaked out reaches the interface 51 and is reflected at different reflectances depending on the position. At this time, the ratio of light returning to the active region related to laser light oscillation in the laser element differs in the plane of the light emitting element 1. In such a state, efficient and stable oscillation as a laser element cannot be obtained.

As described above, since the interface between the light emitting element and the light receiving element is non-uniform, non-uniform reflection occurs at the interface 51. This is a problem with the operation of the light emitting element, especially, the surface emitting laser element. There was a possibility of deteriorating the characteristics.

Therefore, as shown in FIG. 12, in the present invention, in order to prevent the non-uniform reflected light from returning to the surface emitting laser element (flat laser element), the area where the laser element as the light emitting element 1 is formed is formed. A light absorbing layer 50 for absorbing the oscillation wavelength of the laser element is provided in a portion up to the interface 51.

That is, in FIG. 12, n serving as a substrate
A Bragg mirror 53 is formed on the mold semiconductor layer 47.
Then, the intrinsic semiconductor layer 10 is stacked thereon, and the p-type semiconductor layer 46 is further formed thereon. p-type semiconductor layer 46
A Bragg mirror 52 is formed on the intrinsic semiconductor layer 10 side, and a light absorption layer 50 is formed on the Bragg mirror 52. The light absorption layer 50 is formed on the Bragg mirror 52 to form a p-type semiconductor layer 46. The light emitting element 1 of the laser element type is constituted by these.

The upper surface of the p-type semiconductor layer 46 is the interface 51. On this interface 51, an n-type semiconductor layer 58 is formed,
An intrinsic semiconductor layer 13 is formed thereon, and furthermore, p
The light receiving element 2 is formed by forming the mold semiconductor layer 12.

Reference numeral 48 denotes a metal electrode on the interface 51; 49, a metal electrode on the n-type semiconductor layer 49; and 4, a metal electrode on the p-type semiconductor layer 12.

In this case, the laser light is output in the direction of the substrate. Accordingly, the optical fiber 45 serving as an optical transmission path is provided on the back side of the substrate. In order to prevent the light receiving wavelength of the light receiving element 2 from being absorbed by the active layer of the light emitting element 1, the light receiving wavelength of the light receiving element 2 needs to be longer than the light emitting wavelength of the light emitting element 1.

The wavelength at the absorption edge of the light absorption layer 50 is
By setting the wavelength between the light receiving wavelength of the light emitting element 1 and the light emitting wavelength of the light emitting element 1, the output light of the light emitting element 1 can be absorbed, but the input light to the light receiving element 2 can be transmitted. Thus, in order to stabilize the laser oscillation operation of the light emitting element,
The light absorbing layer 50 was provided between a Bragg mirror 52, which is a laser reflection mirror, and an interface 51.

With this configuration, uneven reflection at the interface 51 is eliminated, and the laser oscillation state and the beam profile are stabilized.

[Part 2] The first is an example in which an optical fiber is connected to the light emitting element 1 side and light is extracted from the light emitting element 1 side. An optical fiber 45 may be coupled to the light receiving element 2 side. An example will be described next with reference to FIG.

In this case, since the optical fiber is coupled to the light receiving element 2, the light emitting element 1 is located behind the light receiving element 2, and it is necessary to guide the laser light from the light emitting element 1 to the optical fiber. Therefore, the light absorption layer cannot be interposed in the middle.

Therefore, in such a case, the reflectivity at the portion where the beam output from the light emitting element 1 hits the end face 56 on the opposite side of the light receiving element 2, that is, at the light incident surface portion of the light receiving element 2, has an in-plane reflectance. Therefore, it is good to make it as uniform as possible. This is because the light incident surface is also a light emission surface of the light emitting element 1 and is an interface of the light emitting element 1 that is affected by light reflection.

In FIG. 13A, 14 is a substrate made of an n-type semiconductor, 13 is an intrinsic semiconductor layer on the substrate 14, 1
Reference numeral 2 denotes an n-type semiconductor layer on the intrinsic semiconductor layer 13, and these constitute the light receiving element 2. 11 is the n
P-type semiconductor layer on p-type semiconductor layer 12, 10 is an intrinsic semiconductor layer on p-type semiconductor layer 11, 9 is intrinsic semiconductor layer 10
The upper n-type semiconductor layer. The light emitting element 1 is formed by these 11, 10, and 9.

Further, reference numeral 49 denotes the n-type semiconductor layer 1 of the light emitting element 1.
Reference numeral 48 denotes a metal electrode formed on the p-type semiconductor layer 12 of the light receiving element 2.
48 are used by being grounded. Reference numeral 4 denotes a metal electrode formed on the p-type semiconductor layer 9 of the light emitting element 1, which is a counter electrode of the light emitting element 1. Reference numeral 55 denotes an electrode on the counter electrode side of the light receiving element 2, which is formed on the surface of the substrate 14 which is not on the element stacking side.

The electrode 55 is arranged in a region that does not block the main region of the optical path of the element 1 or 2, thereby opening the optical path. An antireflection coating is applied to the opening (formation of the AR coating layer 57).

In this embodiment, in order to make the reflectivity at the light incident surface of the light receiving element 2 as uniform as possible in the plane, the light incident side end face 56 of the light receiving element 2 is flattened.
The electrode 55 attached to the light incident side end face 56 is
Of the optical path of FIG. In particular, it should be noted that at least the region where the main part of the beam of the output laser light from the light emitting element 1 hits is removed and formed outside the region.

The beam diameter of the laser beam generated by the light emitting element 1 is mathematically widened to infinity, and a region including the whole cannot be defined.

When the beam is output from the light emitting element 1, the diameter increases. Therefore, the area where light reflected by the end face 56 and returned to the active layer of the laser element (light emitting element 1) is finite is finite. The region cannot be determined unconditionally because it depends on the distance from the end face 56 to the light emitting element 1 and the refractive index of the material constituting the region. In addition, the power at the end of the beam is small, and even if the reflected light returns, the influence on the oscillation state is small.

Therefore, as shown in FIG. 13B, in the intensity distribution of the beam output from the light emitting element 1 at the end face 56, the portion where the peak power level is 1 / e ² or more is an aperture. An area for forming the electrode 55 is set so that the optical path is maintained. Here, e is the base of the natural logarithm.

There is a “Gaussian beam” as a generally approximated distribution shape of a light beam. This Gaussian beam contains approximately 86% of power in a region where the intensity distribution is 1 to 1 / e ² . . In addition, considering that the beam spreads and advances, it is considered sufficient if this portion is uniform.

When a laser element is formed, a laser resonator is formed by laminating Bragg mirrors, but it is desirable that reflected light does not return to the laser resonator as much as possible.

Therefore, an anti-reflection coating is applied to the area of 1 / e ² (AR coating layer 5).
7). If the corresponding wavelength of the anti-reflection coat corresponds not only to the oscillation wavelength of the laser but also to the reception wavelength of the light receiving element 2, it is possible to prevent deterioration of the reception sensitivity. Further, it is desirable that the non-reflection coating is uniform in the above-mentioned region of 1 / e ² or more. Normally, when an anti-reflection coating is applied to the surface on which the electrode 55 is provided, the edge of the AR coating layer 57 overlaps around the edge of the electrode 55 as shown in FIG.

The anti-reflection coating does not act sufficiently on the portion having such irregularities 72. Therefore, the electrode 55
Is formed just outside the area where the above-mentioned intensity distribution 1 / e ² is formed, but slightly outside the area, and the portion where the anti-reflection coat has irregularities is within the area where the distribution intensity is 1/1 / e ^2. It is better not to enter.

Alternatively, as shown in FIG. 15, the electrode 55 of the light receiving element 2 may be attached to a portion where the light emitted from the laser element does not hit at all. Which electrode is to be attached depends on the mounting mode. In the example of FIG. 15, flip-chip mounting is appropriate.

Further, in order to make the light returning into the laser resonator as uniform as possible, the output light of the light emitting element 1 passes through not only the end face 56 of the light receiving element 2 but also the inside of the light receiving element 2. It is desirable that the portion is as uniform as possible in the plane direction.

As described above, the embodiment shown in the second example is a transmission / reception photonic IC in which one element of the planar light emitting element and the planar light receiving element is stacked on the other element.
In a photonic IC having a configuration in which a light emitting element is formed on a light receiving element and an optical fiber is coupled to the light receiving element side, output light of the light emitting element at an end surface of the light receiving element that is not adjacent to the light emitting element Wherein the metal electrode of the light receiving element is formed in a region excluding the region from the peak of the power distribution to the portion at which the power becomes 1 / e ² of the peak. By arranging the metal electrode for the counter electrode side on the element side,
This is to prevent the non-uniformity of the reflectivity of the laser light on the light receiving element side, thereby preventing the deterioration of the operating characteristics of the laser element as the light emitting element.

In the first method, in order to suppress the reflection at the interface between the light receiving element and the light emitting element, an absorption layer for the light emitting element wavelength is provided on the light emitting element side from the interface. But,
If “wavelength of light emitting element”> “wavelength of light receiving element”,
As shown in FIG. 16A, there is a light receiving element near the optical fiber to be coupled, and light from the light emitting element is output to the optical fiber via the light receiving element. If the bandgap wavelength of the light receiving element is shorter than the wavelength of the light emitting element, the light receiving element has no sensitivity to the wavelength of the light emitting element and does not cause crosstalk.

In such a wavelength relationship, if the order of the light emitting element and the light receiving element is reversed, the light emitting element absorbs the light to be received by the light receiving element and cannot receive. Therefore,
The light absorbing layer cannot be provided.

When the light-emitting element is a laser, the Bragg mirror on the output side of the light-emitting element has a slightly lower reflectivity to extract output light. Light output from the element is radiated outside the element via the light receiving element. On the end face 67 of the light receiving element 2 which is not adjacent to the light emitting element 1, a metal electrode 68 for applying a voltage to the light receiving element is usually laminated in a ring shape. The output light of the light emitting element reflected by the end face 67 returns to the active layer of the light emitting element via a Bragg mirror designed to have a lower reflectance. If the reflectance of the end face 67 where the light from the light emitting element shines is not uniform in the plane, the ratio of the light returning to the active layer becomes non-uniform in the effective area of the active layer. As a result, there is a possibility that the output of the light emitting element becomes unstable with low efficiency.

In order to avoid such a problem, the second
In the present invention, in a region where the light output from the light emitting element hits the end face 67 of the light receiving element, the metal electrode is arranged outside the area in order to make the reflectivity of the end face 67 uniform. Although it is difficult to define the area where the light output from the light emitting element falls, the diameter of the light beam is generally 1 / e of its peak power.
It is often expressed by the diameter of the part that becomes ² . Further, in a Gaussian beam generally approximated as the shape of a light beam, most of the light power (> 86%) is included from the peak to 1 / e ² .

Furthermore, the light output from the light emitting element spreads as it propagates. Accordingly, the light toward the end of the beam is reflected at an angle slightly deviated from the perpendicular to the end face 67, and as shown in FIG. 16B, the reflected light returns outside the effective active region of the light emitting element. . Therefore, it is not necessary that the reflectance of the end face 67 is uniform over the entire area of the beam, and an uneven portion may be present at the end. 1 /
region until the e ² is the guide, there is no problem even below this distribution intensity region becomes reflectance nonuniformity. Therefore, by setting the position of the metal electrode on the counter electrode side of the light receiving element in a region where the intensity distribution of the laser light emitted from the light emitting element is 1 / e ² or less, the reflectivity of the laser light on the light receiving element side is reduced. This prevents the uniformity from occurring and prevents the deterioration of the operating characteristics of the laser element as the light emitting element.

Next, an example in which a photonic IC is used by being coupled to a single mode fiber that does not form an image of light using a lens will be described as a third example.

[Part 3] An example in which a photonic IC is used by being coupled to a single mode fiber that does not form an image of light using a lens will be described.

When a single mode fiber is used as the optical fiber and the butt coupling without using a lens is applied, the output beam diameter of the light emitting element, which is a component of the photonic IC, is increased in order to increase the coupling efficiency with the photonic IC. Needs to be designed so as to be close to the mode field diameter of the optical fiber.

FIG. 17A shows a substrate 62 made of an n-type semiconductor.
An i-type semiconductor region 61 is formed thereon, and a p-type semiconductor region 60 is formed thereon to form the light-emitting element 1. An n-type semiconductor layer 58 is formed on the upper surface thereof, and the intrinsic semiconductor layer 13 is formed thereon. Further, a p-type semiconductor layer 12 is formed thereon, and the light receiving element 2 is formed by the three layers on the upper surface. Incidentally, 48 is a metal electrode, and 45 is an optical fiber.

In the structure in which the light receiving element 2 is stacked on the light emitting element 1 as shown in FIG. 17A, the element size is set so that the beam diameter of the light emitting element 1 approaches the mode diameter of the optical fiber 45. When the size of the electrode is designed, the light receiving element 2 laminated thereon has a smaller size than the mode diameter of the optical fiber 45, and can receive only a part of the light incident from the optical fiber 45, and the light receiving efficiency is deteriorated.

In order to ensure sufficient light receiving efficiency, the light receiving diameter is desired to be larger than the mode diameter of the optical fiber 45. In this case, since the electrode 48 of the light emitting element 1 is outside the light emitting element area, in a configuration where the beam diameter of the light emitting element 1 is determined in the area determined by the electrode 48, the beam diameter of the light emitting element 1 is It becomes larger than the mode diameter of 48.

Therefore, here, a technology is established that enables transmission and reception of optical signals with the highest efficiency between the light emitting element 1 and the optical fiber 45 and between the light receiving element 2 and the optical fiber 45. The purpose is to:

As described above, when the light receiving element 2 is stacked on the surface emitting type light emitting element 1, the diameter of the light emitting element 1 and the light receiving element 2
Cannot satisfy the conditions for coupling with a single mode fiber.

Therefore, in the present invention, as shown in FIG. 17B, the current confinement layer 69 and the like are provided in the light emitting element 1 to limit the effective diameter D of the active region of the light emitting element 1. here,
The uppermost layer 60 of the light emitting element 1 (the layer on which the electrode 48 is provided and the light receiving element 2 is laminated) is made larger than the effective diameter D described above.

By doing so, the light emitting element 1
It is possible to ensure the size of the diameter of the light receiving element 2 stacked thereon. In consideration of the light receiving efficiency, the diameter of the light receiving element 2 is set to be equal to or larger than the effective diameter D of the active region.

Here, the active region of the light emitting element 1 is limited, for example, by limiting the current supply between the uppermost p-type semiconductor layer 60 and the active layer (intrinsic semiconductor layer 61) as shown in FIG. In order to secure an area, a current block 63 may be provided. Note that the current block is a portion that does not pass current.

As described above, the layer having the current block 63 may be provided between the p-type semiconductor layer 60 and the intrinsic semiconductor layer 61. At this time, the portion 64 through which the current flows has the same p-type as the p-type semiconductor layer 60 as the uppermost layer.

When the light emitting element 1 is a laser element, an optical resonator is required to form the laser element.
A Bragg mirror is required as this optical resonator. In the case of the present invention, this Bragg mirror may be located in either of the above 60 and 64. In addition, the current block 63
It may be in the active layer 61 as shown in FIG.
Also, it may be in the n-type layer below the active layer.

In order to form a current blocking layer, a portion for passing a current and a portion for blocking a current in the layer are usually formed separately by etching. Alternatively, a current block may be formed by uniformly laminating a material through which current flows, and then semi-insulating a portion through which current does not flow by means such as diffusion of impurities. In FIG. 18, metal electrodes other than 48 are not shown, but actually exist.

For some elements, light input to the light receiving element 2 passes through the light emitting element 1. If the beam diameter of the light emitting element 2 is substantially equal to the mode diameter of the optical fiber 45, and if the optical fiber 45 and the element 1 or 2 are butt-coupled, almost all of the beam input from the optical fiber 45 to the light receiving element 2 Pass through the effective active region of the light emitting element 1.

However, depending on the use of the device, even if the coupling efficiency from the light emitting device 1 to the optical fiber 45 is degraded, the optical fiber 45 may not be placed at a position close to the device.

In order to cope with such a use case, in consideration of the spread of the beam output from the optical fiber 45, the current block 63 is transparent (that is, transparent) with respect to the light receiving wavelength of the light receiving element 2. It is desirable that

In the above-described example, the beam diameter of the light emitting element 1 is limited by using the current confinement layer, and the diameter of the light receiving element 2 is sufficiently ensured. There is also a method in which the beam diameter of the light emitting element 1 is limited and the diameter of the light receiving element 2 is sufficiently large. This is a method as shown in FIG. 19, and when forming a metal electrode 64 on the counter electrode side on a surface of the substrate (n-type semiconductor layer) 62 of the light emitting element 1 which is not on the element stacking side, an opening portion of the metal electrode 64 is formed. Is relatively small, and the light receiving element 2 on the light emitting element 1 is formed to be sufficiently larger than the opening.

Needless to say, the substrate 62 may be an n-type substrate, that is, an n-type or p-type substrate is used, and light is input / output from the substrate side. An electrode 48 having a large inner diameter is attached to the side on which the light receiving element 2 is laminated, and the light receiving element 2 having a sufficient diameter is laminated, and a part of a large oscillation profile is cut out by the electrode 64 attached to the substrate 64 of the light emitting element 1. , The output beam diameter is determined.

However, in the case of this configuration, the light emitting element 1 emits light even in a portion which is not extracted as an output beam, behind the electrode 64. These lights are finally converted into heat inside the device. Therefore, it is necessary to pay sufficient attention to heat radiation when mounting the element.

Although this element has poor thermal efficiency, it is simple to manufacture and can be manufactured at low cost. In addition, the light is received by the light receiving element 2.
When inputting and outputting from the side, as shown in FIG. 20, it is desirable that the output light of the light emitting element 1 be provided at the position where the counter electrode 4 of the light receiving element 2 is not blocked by the electrode 4.

Although the above embodiment is directed to an optical IC for wavelength multiplexed bidirectional transmission, the present invention is also applicable to a photonic IC for ping-pong transmission of the same wavelength for transmission and reception. This example will be described.

[4] A photonic IC for ping-pong transmission will be described. As shown in FIG. 21, this IC is formed by laminating a planar light-emitting element 1 and a light-receiving element 2, and the light-receiving element 2 is not a normal light-receiving element but has the same function as an electroabsorption modulator. To

An electro-absorption modulator absorbs light when an electric field (voltage) is applied to the element (acts as a light-receiving element), and transmits light when no electric field is applied. As shown in FIG. 21, the mounting is performed so that the light receiving element 2 comes closer to the optical fiber 45.

At the time of reception, a sufficient bias voltage is applied to the light receiving element 2 to absorb light. When transmitting, the bias voltage of the light receiving element 2 is reduced so that light is not absorbed, and the output light of the light emitting element 1 is transmitted through the light receiving element 2 and the optical fiber 4
To reach 5.

In the transmission / reception optical IC for ping-pong transmission, transmission and reception are not performed at the same time. Therefore, even if the technology described in the first embodiment is applied, the function of the layers 58 and 60 as an electromagnetic shield is meaningless. There is no.

However, by connecting the layers 58 and 60 with the metal electrode 3 and grounding them, the polarities of the applied voltages to the light emitting element 1 and the light receiving element 2 become the same, and there is an advantage that the peripheral circuit is simplified. .

Also, in the case of ping-pong transmission, FIG.
As in the example shown in (b), a current confinement layer for limiting the beam diameter is provided in the light emitting element, a sufficient light receiving diameter is given to the light receiving element 2, and the light receiving element and the light receiving element are connected to the optical fiber. It is desirable to improve the coupling efficiency.

The invention described in the second embodiment is as follows.
This is a technique for stabilizing the operation of a light emitting element in a photonic IC in which a planar light emitting element and a light receiving element are vertically stacked, and a technique for improving the coupling efficiency of the light emitting element and the light receiving element to an optical fiber. Was. And the first
In both the techniques of the second embodiment and the second embodiment, the planar light emitting element and the light receiving element are vertically stacked, but the technique of the present invention is such that the light emitting element 1 and the light receiving element 2 are of a stripe type. It can also be applied to photonic ICs.

An example will be described as a third embodiment.

(Third Embodiment) The invention described in the third embodiment relates to a light emitting device having a pin structure (a layer structure including a p-type semiconductor layer, an intrinsic semiconductor layer, and an n-type semiconductor layer) and a pin structure. One of the light receiving elements is stacked on the substrate, the other element is placed on the uppermost layer of the one element or on the extension of the uppermost layer, and the impurity type of the lowermost layer of the other element is the one type. Stacked so as to be different from the impurity type of the uppermost layer of the element, the uppermost layer or the extension of the uppermost layer of the one element and the extension of the lowermost layer or the lowermost layer of the other element are connected by a metal electrode pattern, The electrode pattern is characterized in that it is used by being grounded at least in an alternating current.

This is a modification of the first embodiment, and is applicable not only to a photonic IC having a planar light emitting element and a light receiving element but also to a photonic IC having a stripe light emitting element and a light receiving element. It is shown.

Description will be made with reference to the drawings. FIG. 22 (a)
Is an example of an element in which a light emitting element 1 and a light receiving element 2 of a stripe type are coupled via a waveguide type WDM coupler 70 and the like, and is a plan view, and FIG.
It is A sectional drawing.

Reference numeral 90 denotes a photonic IC main body. As the photonic IC main body 90, a light emitting element 1 and a light receiving element 2 are arranged on a substrate 91 in parallel. An optical waveguide 70 for guiding an optical signal is formed between the light emitting element 1 and the light receiving element 2 and the optical signal input / output end 90a of the photonic IC body 90. Since the light emitting element 1 and the light receiving element 2 are juxtaposed, the element side end of the optical waveguide 70 is branched into two branches, and the light from the light emitting element 1 is guided to the input / output end 90a, and the input / output end 90a From the light receiving element 2. The optical fiber 45, which is a transmission path of an optical signal, is disposed such that its tip is close to the input / output end 90a.

That is, the waveguide 70 coupled to the light emitting element 1 and the light receiving element 2 is a wavelength multiplexing coupler, which couples the light input from the optical fiber 45 to the light receiving element 2 and outputs the light from the light emitting element 1 The resulting light is coupled to the optical fiber 45.

As shown in FIG. 22 (b), the light receiving element 2 has a layer composed of an intrinsic semiconductor layer 13i and a semi-insulating region 71 laminated on a substrate 14 made of an n-type semiconductor.
This is a configuration in which the type semiconductor layers 12p are stacked.

On the p-type semiconductor layer 12p, an n-type semiconductor layer 11i, an intrinsic semiconductor layer 11i, and a p-type semiconductor layer 9p are sequentially laminated. The light-emitting element 1 is composed of these 12p, 11i, and 9p. 4 is an electrode on the p-type semiconductor layer 9p;
Is a ground electrode formed on the n-type semiconductor layer 3.

In the structure shown in FIG. 22, the light emitting element 1 is stacked on the p-type semiconductor layer 12p on the uppermost layer of the light receiving element 2, but the effective areas of the element do not overlap. That is,
The intrinsic semiconductor layer 13i of the light-receiving element 2 is formed at a position completely deviated from the position where the light-emitting element 1 is formed. The light receiving elements 2 are arranged so that they do not overlap each other.

In this example, as in the example described in the first embodiment, the layer 11n where the light emitting element 1 and the light receiving element 2 are in contact with each other.
And 12p are connected by a metal electrode 3, and this electrode 3 is used by grounding.

The waveguide 70 coupled to the light emitting element 1 and the light receiving element 2 is a wavelength multiplexing coupler, which couples light input from the optical fiber 45 to the light receiving element 2 and outputs light from the light emitting element 1. The light is coupled to the optical fiber 45.

FIG. 23 shows an example of a photonic IC in which a stripe type light emitting element 1 and a stripe type light receiving element 2 are vertically stacked and arranged in a two-layer structure. FIG. 23 (a) is a plan view and FIG. FIG. 23B shows a cross-sectional view taken along the line BB. 70a and 70b are optical waveguides.

As described above, the light emitting element and the light receiving element of the stripe type may be vertically stacked. The boundary layer between the light-emitting element 1 and the light-receiving element 2 is connected by a metal electrode and grounded for use as in the case of FIG. The optical waveguide 70a,
70b functions by wavelength multiplexing coupler betting,
The waveguides 70a and 70B are vertically stacked and manufactured using the wavelength dependence of the coupling amount between the waveguides.

In the example of FIG. 22, two-way wavelength multiplexing transmission is supported by using a wavelength multiplexing coupler. However, the same wavelength ping-pong transmission is supported by using a power splitter instead of the wavelength multiplexing coupler. You may do it.

As described above, the slit type photonic I
C, the light-emitting element 1 and the light-receiving element 2 are each formed by stacking the other element on one element so that the n-type layer of one element is adjacent to the p-type layer of the other element. The adjacent n-type layer of one element and the p-type layer of the other element are connected by an electrode pattern, and this electrode pattern is configured to be at least AC grounded.

Thus, an arrangement structure is obtained in which the n-type layer of the light-emitting element 1 is adjacent to the p-type layer of the light-receiving element 2, or the p-type layer of the light-emitting element 1 is adjacent to the n-type layer of the light-receiving element 2. The adjacent p-type layer and n-type layer are connected by an electrode pattern 3 in the photonic IC, and the connected electrode 3 is electrically grounded for use. As in the first embodiment in which the power supplies are overlapped with each other, simplification of the power supply and suppression of crosstalk can be achieved.

That is, the light emitting element 1 normally applies a voltage having a polarity such that a forward bias is applied to the diode structure, and the light receiving element 2 applies a voltage having a polarity such that the reverse bias is applied. Therefore, when the adjacent p-type layer and n-type layer are connected by the electrode pattern 3 as described above and this electrode pattern 3 is used by grounding, the positive and negative voltages applied to the light emitting element 1 and the light receiving element 2 are the same. become. As a result, the power supply voltage of the circuit for driving the elements can be either positive or negative, that is, only a single DC power supply can be used, and the electronic circuit configuration can be simplified.

Further, as in the present invention, the layer at the boundary between adjacent elements is grounded and used, so that the grounded layer (the p-type semiconductor layer 12p and the n-type semiconductor layer 11n in the configuration of FIG. 22) is used. Acts as an electromagnetic shield surface. Therefore,
Crosstalk between transmission and reception due to electromagnetic coupling between the light emitting element and the light receiving element through the light emitting surface and the light receiving surface is eliminated,
The receiving sensitivity of the element is improved.

In the above example, only a portion directly related to the present invention is shown, taking a relatively simple element configuration as an example. In actual devices, various measures are taken to improve the performance,
The present invention is also applicable to a device with such a device. Further, in each example described in the embodiment, for convenience, up and down, or vertical and horizontal, left and right directionality is specified and described, but this is only for convenience, and how to set the direction reference Accordingly, for the sake of explanation, it is determined relatively and is not limited.

[0197]

As described above, according to the present invention,
Since the interface layer between the light receiving element and the light emitting element of the surface type transmission / reception photonic IC is configured to be grounded, electric crosstalk between transmission / reception can be reduced and the reception sensitivity can be improved. In addition, since the light emitting element does not have the non-uniform reflected return light reflected from the light receiving element, the oscillation state can be stabilized, and the transmission characteristics can be improved. Become.
Further, the beam diameter of the light emitting element is determined by the current confinement layer, and the diameter of the surface on which the light receiving element is laminated is not limited, so that the light emitting element and the light receiving element satisfy the coupling condition with the optical fiber. As a result, sufficient output light power and reception sensitivity can be obtained, and transmission characteristics can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the present invention, and is a diagram for explaining a conceptual diagram of the present invention.

FIG. 2 is a view for explaining the present invention, showing one of the first embodiments of the present invention.

FIG. 3 is a view for explaining the present invention, and is a plan view showing an example of the shape of the electrode 4 according to the first embodiment of the present invention.

FIG. 4 is a diagram for explaining a problem to be solved by the present invention.

FIG. 5 is a diagram showing a problem.

FIG. 6 is a view for explaining the present invention, showing one of the second embodiments of the present invention.

FIG. 7 is a diagram for explaining a problem to be solved by the present invention.

FIG. 8 is a diagram for explaining the present invention, and is a diagram showing the first embodiment of the present invention.

FIG. 9 is a diagram for explaining the present invention, and is a diagram showing a configuration example when the present invention is applied to flip chip mounting.

FIG. 10 is a diagram for explaining the present invention, showing an example of a mounting method of the photonic IC of the present invention.

FIG. 11 is a diagram for explaining another problem to be solved by the present invention.

FIG. 12 is a view for explaining the present invention, showing one of the second embodiments of the present invention.

FIG. 13 is a diagram for explaining the present invention, showing one of the second embodiments of the present invention.

FIG. 14 is a diagram for explaining the present invention, and is a diagram for explaining a second embodiment of the present invention.

FIG. 15 is a diagram for explaining the present invention, and is a diagram for explaining a second embodiment of the present invention.

FIG. 16 is a diagram for explaining the present invention, and is a diagram for explaining an example of the second embodiment of the present invention.

FIG. 17 is a diagram for explaining the present invention, and is a diagram for explaining the third embodiment of the present invention.

FIG. 18 is a diagram for explaining the present invention, showing an example of the second embodiment of the present invention.

FIG. 19 is a diagram for explaining the present invention, and is a diagram for explaining the second embodiment of the present invention.

FIG. 20 is a view for explaining the present invention, showing one of the second embodiments of the present invention.

FIG. 21 is a view for explaining the present invention, showing one of the second embodiments of the present invention.

FIG. 22 is a view for explaining the present invention, showing one of the third embodiments of the present invention.

FIG. 23 is a view for explaining the present invention, showing one of the third embodiments of the present invention.

FIG. 24 is a diagram for explaining a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Light-emitting element 2 ... Light-receiving element 3, 4, 5, 6, 7, 8, 32, 34, 39, 48, 4
9, 55, 59, 66, 68 ... metal electrode 9, 12, 20, 46 ... p layer (p-type semiconductor layer) 10, 13, 19, 22 ... i layer (intrinsic semiconductor layer) 11, 18, 21, 30 , 47, 58... N-layer (n-type semiconductor layer) 14, 62... N-layer (substrate) 15... Electrode provided on layer 12 16. Electrode provided on layer 11 17. Electrode connecting electrodes 15 and 16 23. p layer (substrate) 24 dielectric layer 25, 26, 33, 38, 40 bonding electrode pad 27, 60 p type region (p type semiconductor region) 28, 61 ... i region (intrinsic semiconductor region) 29, 51, 54, 56, 67 Interface 31 Semi-insulating substrate 35, 36, 65 Parasitic capacitance 37 Ground electrode 41 Substrate for flip chip 42 Submount 43 Photonic pad substrate 44 Element region 45 Optical fiber 50 ... Absorbing layers 52 and 53 Bragg mirror 57 Non-reflective coating 63 Current block 64 Current passing area 69 Current constricting layer 70 Wavelength multiplex coupler 71 Semi-insulating area 72 Non-reflective coating irregularities 73 Waveguide

Claims (7)

[Claims] 1. A planar light emitting element and a planar light receiving element are superposed on one element such that an n-type semiconductor layer of one of the elements and a p-type semiconductor layer of the other element are adjacent to each other. In a transmission / reception photonic IC in which elements are stacked, the n-type layer of one of the adjacent elements and the p-type layer of the other
A transmitting / receiving photonic IC, wherein a mold layer is connected by an electrode pattern in the IC, and the electrode pattern is used by being grounded at least in an AC manner. 2. The transmitting / receiving photonic I according to claim 1.
C. The transmitting / receiving photonic IC according to C, wherein the IC is formed on an insulating substrate or a semi-insulating substrate. 3. A planar light emitting device is laminated on a semiconductor substrate,
In a transmission / reception photonic IC in which a planar light receiving element having an absorption edge wavelength longer than the oscillation wavelength of the planar light emitting element is stacked on the planar light emitting element, the planar light emitting element includes a pair of Bragg mirror layers as active layers. And the Bragg mirror layer on the far side from the semiconductor substrate, between the electrode for passing a current to the active layer via the Bragg mirror layer, the oscillation wavelength and the A transmission / reception photonic IC comprising an absorption layer having an absorption end wavelength at an intermediate wavelength of the absorption end wavelength of the planar light receiving element. 4. A transmission / reception photonic IC in which one of a planar light-emitting element and a planar light-receiving element is stacked on top of another element, wherein an electrode of the light-receiving element is adjacent to the light-emitting element. A transmission / reception photonic IC wherein the power distribution of the output light of the light emitting element on the end face on the non-existing side is formed outside a region of 1 / e ² (e is the base of natural logarithm) or less of its peak. . 5. The transmission / reception photonic IC according to claim 4, wherein the area is substantially uniformly coated with a non-reflection coating, and a wavelength band corresponding to the non-reflection coating corresponds to an emission wavelength of the light-emitting element and a wavelength of the light-receiving element. A transmitting / receiving photonic IC including a light receiving wavelength. 6. A transmitting / receiving photonic IC in which a planar light receiving element is stacked on a planar light emitting element, wherein the light emitting element has an effective active area limited by a structure such as a current block. Formed above the limited effective active area, the effective light receiving area in the light receiving layer of the light receiving element, assuming that the output light of the light emitting element reaches the light receiving layer, A transmission / reception photonic IC, wherein the transmission / reception photonic IC is configured to occupy a range including at least 95% or more of the total power reaching a plane including a light receiving layer. 7. A transmission / reception photonic IC in which a light emitting element having a pin structure and a light receiving element having a pin structure are stacked, and one of the light emitting element and the light receiving element is stacked on a substrate. The other element is formed on the uppermost layer of one element or on an extension thereof, and these elements are formed such that the impurity type of the lowermost layer of the other element is different from the impurity type of the uppermost layer of the one element. A transmission / reception photonic IC wherein the two layers are stacked and connected by a metal electrode pattern, and the electrode pattern is at least AC grounded.