JPS59200475A - Composite photosemiconductor element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Technical field to which the invention pertains] The present invention relates to a composite optical semiconductor device consisting of a semiconductor light emitting device and a semiconductor photodetecting device, and in particular improves each current path of the semiconductor light emitting device and the semiconductor photodetecting device. The present invention relates to a composite optical semiconductor device.

[Prior art and its problems] The output characteristics of a light emitting diode (hereinafter abbreviated as LED) as a semiconductor light emitting device has less temperature change and better linearity than a semiconductor laser, and apart from problems with response and power level, It is a very easy to use light source.

However, when actually used in analog transmission, for example, it is necessary to further compensate for temperature characteristics and linearity.

In this compensation method, a broadband photoelectric negative feedback method (S56 Institute of Electronics and Communication Engineers General Conference 2226), which simultaneously compensates for both temperature and linearity and has excellent stability, has recently been used.

This method detects a portion of the optical output of a semiconductor light emitting device and compensates for nonlinear distortion of the semiconductor light emitting device.

In order to compensate for such nonlinear distortion, it is desirable to form the semiconductor light emitting device and the semiconductor photodetecting device monolithically.

Conventionally, a structure in which a semiconductor light emitting element and a semiconductor photodetecting element are monolithically formed has been devised as shown in FIG. 1, which is partially shown in cross section. That is, for example, L.E.
A light passage part (1-30) for passing the light output from the LED (1-10) to the outside is provided at approximately the center of one surface of the semiconductor light emitting element consisting of D (1-10), For example, a photodiode (hereinafter abbreviated as FD) (1-2
A semiconductor photodetecting element consisting of 0) is monolithically formed in a layered manner. , the LED (1-10) is made of, for example, N-type GaAs on a substrate (1-11) made of, for example, P-type GaAs.
A first composition layer (1-13) made of, for example, P-type GaAlAs, via a current confinement layer (+-1, 2) made of As.
is formed. Furthermore, this first composition layer (1-1
3) On top, an active layer (1
-14), a second composition layer (1-15) made of, for example, N-type GakllAs is formed.

Next, the PD (1-20) is formed by applying, for example, a P-type GaA
A P-type layer (1-22> consisting of s is formed, and P-1-
It has an N structure, and it also has an N structure made of N-type Ga1VAs.
The mold layer is the second composition layer (1-15) of the LED (]-10).
) is shared with In addition, LED (1-10)+7)
On the other hand, (1-17> Ha, L E D
(1-10) and outside the light receiving part of the PD (1-20), and the other electrode (1-16) is the LE
The groove P provided on the other surface of D (1-10)
D(]-20)+7) On the other hand (7)! The pole is L E D
One electrode (1-17) of (]-10) is also used, and the other electrode (1-23) is provided on one surface of the light receiving section of the FD (1-20).

Due to the above structure, the light output from the active layer (1-14) is
It is detected by the PD (1-20), and the light passing part (1-20)
-30) and is partially output to the outside through an optical fiber (1
-40).

Further, the output of the PI) (1-20) is guided to an external electronic circuit to constitute the above-mentioned broadband optical/electrical negative feedback. However, such a conventional structure has the following problems.

In order to implement a broadband optical/electrical negative feedback system, LEDs (1-
PD (1-20) that detects a part of the optical output from 10)
Although it is necessary to obtain a true monitor current of the LED (x-10) from K, it is difficult to obtain an accurate monitor current with the above structure.

That is, the electrode (1-17), which also serves as the electrode for each of the LED (1-10) and the PD (1-addition), is the electrode for the FD (1-addition).
20), so the LED
(1-10) (DIE flow path (1-50) and FD (1
-20) (7) The current path (1-60) is close to or overlaps with the current path (1-60).

Therefore, in the above structure, the PD from the LED (l-10) side
Since current leakage occurs to the (1-20) side, PD (1-2
0)-t'LED (1-10)% of the LED (1-10) could obtain a monitor current that was too high, and it was not possible to achieve high-precision broadband optical-electrical negative feedback.

[Object of the Invention] The present invention has been made in consideration of the above-mentioned problems, and its purpose is to prevent current leakage from a semiconductor device element to a semiconductor photodetector element. It is an object of the present invention to provide a composite optical semiconductor device capable of obtaining a true monitor current of a semiconductor light emitting device and performing effective broadband optical/electrical negative feedback.

[Overview of the Invention] The present invention provides a composite optical semiconductor device in which a semiconductor light emitting device and a semiconductor photodetection device that detects a part of the light output from the semiconductor light emitting device are monolithically configured, and a method for driving the semiconductor light emitting device. It is an object of the present invention to provide a composite optical semiconductor device in which a driving current of a semiconductor light emitting device and a detection current of a semiconductor photodetecting device are independent from each other in a common layer through which a current and a photodetection current of a semiconductor photodetecting device flow.

[Effects of the Invention] According to the present invention, the driving current path of the semiconductor light emitting device and the photodetection current path of the semiconductor photodetecting device can be made independent,
Therefore, it is possible to obtain a composite optical semiconductor device that prevents current leakage from the semiconductor light emitting device to the semiconductor photodetection device, obtains a true monitor current of the semiconductor light emitting device from the semiconductor photodetection device, and performs effective broadband optical/electrical negative feedback. I can do it.

[Embodiments of the Invention] A first embodiment of the invention will be described with reference to FIG. 2, which partially shows a cross section.

That is, for example, L has a PN junction forming a light emitting part.
On one surface of the semiconductor light emitting element consisting of ED (2-10), a semiconductor photodetecting element consisting of, for example, FD (2-20), which detects a part of the light output from this LED (2-10), is arranged in an annular shape. It is formed monolithically in layers.

For example, the impurity concentration of LED (2-10) is 1×1018
cIIL-3, thickness 200 to 300 pm OP type G
A current confinement layer (2-12) made of N-type GaAs with a thickness of 2 μm to 3 μm is formed on a substrate (2-11) made of aAs, for example, with an impurity concentration of I P-type AJxGa+ -xAs (
The first composition layer (x=0.3 to 0.4) (2-1
Further, on this first composition layer (2-13), for example, an N layer with an impurity concentration of lX10a++ and a thickness of 1 μm is formed.
fil ) J xGa s −xAs (x = 0.
For example, N-type All xGa 1-xAs (x
= 0.3 to 0.4).
5) is formed.

Incidentally, the current confinement layer (2-12) is formed in order to improve current concentration in a part and obtain high luminous efficiency.

Next, PD(2-20) is placed on the N-type layer to a thickness of, for example, 4
For example, the impurity concentration is I x 1010 l8 through the low impurity concentration layer (2-21) made of GaAs of μm.
A P-type layer (2-
22) is formed and has a P-i-N structure. still,
The N-type layer at this time is shared by the M2'' composition layer (2-15) (!:) of the LED (2-10).

Further, one electrode (2-1?) of the LED (2-10) is connected to the upper surface of the second composition layer (2-15) and the PD (
2-20) is arranged in an annular manner inside the photodetection section,
The other electrode (2-16) is provided on the lower surface of the substrate (2-11), and one electrode (2-24) of I) D (2-20) is provided with a second composition. On the upper surface of the layer (2-15), and on the PD (2-20), the photodetecting portion (2-2
')) is arranged in a ring shape on the outside of the other electrode (2).
-23) is jD (2-addition) (7) P-type layer (2-22)
provided on the upper surface of the

Here, L on the upper surface of the second composition layer (2-15)
One electrode (2-17) of ED (2-10) and PD (
2-20) On the other hand, O11 [(2-24) Nosuke U, Example Eva is said to be 50 μm to 70 μm.

In the above structure, the light output from the active layer (2-14) is partially detected by the PD (2-20), and is also detected by the light passing part (2-30) or the outside of the electrode (2-17). A portion of the light is also output to the outside through the light and enters the optical fiber (1-40).

On the other hand, the output of the PD (2-20) is guided to an external electronic circuit to constitute broadband optical/electrical negative feedback.

i.e. %LED (2-10) (D one electrode (2-17)
is formed inside the photodetecting part (2-2"i) of the PD (1-1o), and one electrode (2-24" of the FD (2-20))
) is provided outside the photodetector (2-25) o of the PD (2-2(J)), so the LED (2-10)
'i7) Current path (2-30) is PD (2-20)o
They are located inside the current path (2-40) and are independent from each other.

Therefore, current leakage from the LED (2-10) side to the FD (2-20) side can be prevented, and the PD (2-20
)RUED(2-10) true monitor current can be obtained.

Note that the positional relationship between one electrode (2-17) of the LED (2-10) and one electrode (2-24) of the FD (2-20) in this first embodiment is reversed. Also in the case, FD(
2-20) (7) [i path is L E IM) inside the tfi path and are independent from each other.

In addition, in this specification, the term "the LED drive current path and the PD photodetection current path are independent" means that the LED drive current path and the PD photodetection current path are independent.
This means that the leakage current to the PD can be considered to be about 1/100 or less of the photodetection current of the PD.

In addition, PD(2-20) is formed in a ring shape,
This shape may be a polygon such as a triangle or a quadrangle, or an ellipse, and it is sufficient that the shape is not a complete annular shape but a part thereof.

Next, a second embodiment of the invention will be described with reference to FIG.

That is, for example, N-type Al x Ga 1-x As (x = 0.2
) is formed, and further on this first composition layer (3-12) is formed a first composition layer (3-12) consisting of, for example, N-type All xGa 1-XAS (x=0.05). Via the active layer (3-13), for example, Nfi AJxG
A second composition layer (3-14) consisting of al-xA,s (x=0.2) is formed. Further, a P+ type diffusion layer (3-15) is formed in a part of the second composition layer (3-14) and the active layer (3-13), and this diffusion layer (3-15) is formed in a part of the second composition layer (3-14) and the active layer (3-13).
A first electrode (3-16) is formed on a part of the upper surface of -15), and a second composition layer (3-14) adjacent to the first electrode (3-16) formation part. A second electrode (3-17) is formed on a part of the surface and constitutes an LED.

Next, a second composition layer (3
-14) A rectangular low impurity concentration layer (3-18) made of, for example, GaAs is formed on a part of the surface, for example, by using GaAs.
A P-type layer (3-19) made of As is formed, and a third electrode (3-20) is further formed on this P-type layer (3-19). Furthermore, this low impurity concentration layer (3-1
8) The fourth electrode (3=14) formed on the first composition layer (3=14) between the formation part and the second electrode (3-17) of the LED
3-21) constitutes the PD.

With this structure, the f-type diffusion layer (
3-15) and the N-type layers (3-13) and (3-14), light is emitted from the P-N junction, and part of the light output is absorbed by the first electrode (3-16) formed. The surface of the second composition layer (3-14) that is not coated is outputted to the outside.

In addition, the other part of the above-mentioned optical output is
It is detected from the i-N junction and the LED is monitored. Note that the second composition layer (3-14) is commonly used as one semiconductor layer constituting each of the LED and PD in areas other than the portion where the LED diffusion layer (3-15) is formed.

As described above, according to the second embodiment described above, the photodetection current path (3-22) of the PD is the drive current path (3-23) of the LED,
are parallel and independent of each other.

Furthermore, the LED and the PD for monitoring the LED can be manufactured in a monolift with more than twice the integration density compared to conventional methods.
Therefore, electric circuit elements such as the LED drive circuit and the photodetection circuit of P1) can also be combined.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing a part of a conventional example in which LEDs and PDs are configured seven-dimensionally, in cross section, Fig. 2 is a perspective view showing a part of a first embodiment of the present invention in cross section, and Fig. 3 FIG. 2 is a perspective view showing a part of a second embodiment of the invention in cross section. 1-40... Optical fiber, 2-10, 2-11 to 2-17, 3-13 to 3
-17... L E D, 2-15 and 2-21 to 2
-24. :3-14 and 3-18 to 3-21...P
D, 3-11..Substrate, 3-12.First composition layer, 2-
30.3-23...LED drive current path, 2-40
, 3-22...PD photodetection current path. Agent Patent attorney Kensuke Chika (and 1 other person) Figure 1 Figure 2 Figure 8 Procedural amendment (voluntary) 1. Case description Patent Application No. 73802 of 1982 2 Name of the invention Composite optical semiconductor device 3 Person making the amendment Relationship to the case Patent applicant (307') Tokyo Shibaura Electric Co., Ltd. 4 Agent address 100 Tokyo 1-1-6 Uchisaiwai-cho, Chiyoda-ku Detailed explanation of the invention in the specification Drawing 6 Contents of amendment (1) “Composite optical semiconductor device (2)” on page 7, line 9 of the specification
) Change "05μm" on page 9, line 13 of the specification to "1μm"
and correct it. (3) 1- from page 11, line 10 to line 11 of the specification
One electrode (2-17) J of the LED (2-10) is connected to [P
Correct with the photodetector (2-26)J of D (2-addition). (4) “Inside” on page 11, line 14 of the specification is “outside”
and correct it. (5)Amend Figure 2 of the drawings as shown in the attached sheet. that's all

Claims (6)

[Claims] (1) In a composite optical semiconductor device in which a semiconductor light emitting device and a semiconductor photodetecting device that detects a part of light output from the semiconductor light emitting device are monolithically configured, one semiconductor layer of the semiconductor light emitting device and One semiconductor layer of the semiconductor light detecting element is a common layer, and the electrode of the semiconductor light detecting element and the electrode of the semiconductor light detecting element are provided independently, and the driving current of the semiconductor light detecting element and the electrode of the semiconductor light detecting element are independent of each other. A composite optical semiconductor device characterized in that the drive current path and the photodetection current path are independent from each other within the common layer through which the photodetection current flows. (2) The composite optical semiconductor device according to claim 1, wherein the photodetection current path of the semiconductor photodetection device is located outside the drive current path of the semiconductor light emitting device. (3) The composite optical semiconductor device according to claim 1, wherein the photodetection current path of the semiconductor photodetector is located inside the drive current path of the semiconductor light emitting device. (4) The composite optical semiconductor device according to claim 1, wherein the photodetection current path of the semiconductor photodetection device is parallel to the drive current path of the semiconductor light emitting device. (5) The composite optical semiconductor device according to claim 1, wherein the electrodes of the semiconductor light emitting device and the semiconductor photodetecting device are all monolithically formed on the main surface. (6) The composite optical semiconductor device according to claim 1, wherein the semiconductor photodetecting device is formed in an annular shape. (The composite optical semiconductor device according to claim 1, wherein the dynamic conductor photodetecting device is formed in a rectangular shape.