JP2750180B2 - Edge emitting light emitting diode and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an edge-emitting light-emitting diode used as a light source in a medium-capacity and medium-distance system such as an optical communication, in particular, a LAN (local area network), and manufacturing thereof. About the method.

[Conventional technology]

Conventionally, this type of light-emitting diode has been described in the 1987 IEICE 70th Anniversary General Conference Proceedings, No.882,
1.5 μm band edge-emitting diode, page 4-44 ”.

This uses the same refractive index waveguide structure as a semiconductor laser in order to increase the coupling efficiency of the optical output to the single mode fiber.
In addition to coating a non-reflection film such as an Al ₂ O ₃ film, a light absorption layer is provided inside the device.

Hereinafter, a method for manufacturing such an edge-emitting light emitting diode will be described with reference to FIGS. The fifth
FIG. 6 is a side view of a light emitting diode, FIG. 6 is another side view thereof, and FIG. 7 is a sectional view taken along line AA of FIG.

First, a p-type InP current blocking layer 2 is formed on an n-type InP substrate 1.
After the n-type InP current blocking layer 3 and the p-type InP current blocking layer 3 are sequentially formed by the liquid phase epitaxy,
A V-shaped groove 4 is formed in the current blocking layer 2 and the n-type InP substrate 1 by etching using, for example, a mixed solution of hydrochloric acid and phosphoric acid. Thereafter, the n-type InP cladding layer 5 and the InGaAsP
The active layer 6 is sequentially formed by a liquid phase growth method.
A p-type InP cladding layer 7 and a p-type
InGaAsP contact layers 8 are sequentially deposited by a liquid phase growth method. Thereafter, an SiO ₂ film 9 is coated on the p-type InGaAsP contact layer 8. For example, when the length of the InGaAsP active layer 6 is set to 500 μm, the SiO ₂ film 9 on the portion 150 μm from one end face of the InGaAsP active layer 6 is formed. _{2 The} film 9 is removed so that the portion of the InGaAsP active layer 6 is energized.
As a result, a portion of the InGaAsP active layer 6 that is energized becomes a light emitting portion, and a portion that is not energized becomes a light absorbing portion. Thereafter, an AuZn electrode 10 is formed on the p-type InGaAsP contact layer 8 including the SiO ₂ film 9, and an AuGeNi electrode 11 is formed on the back surface of the n-type InP substrate 1.
Was coated with a light non-reflective film (not shown) for suppressing laser oscillation to complete it.

[Problems to be solved by the invention]

However, in the above-mentioned conventional light emitting diode,
Since the InGaAsP active layer 6 formed in the same groove 4 is used for both the light emitting portion and the light absorbing portion, the light emitting portion and the absorbing portion have the same thickness. However, the InGa that can be formed in the groove 4
Since there is a limit to the thickness of the AsP active layer 6, it is necessary to lengthen the absorption portion in order to increase the light absorption effect,
Therefore, there has been a problem that the length of the element becomes long and the density of the element cannot be increased.

SUMMARY OF THE INVENTION An object of the present invention is to provide an edge emitting light emitting diode in which a high light absorbing effect can be expected even in a short light absorbing portion, and a method for manufacturing the same, in view of the above-mentioned problems.

[Means for solving the problem]

In order to achieve the above-described object, the present invention provides, in a current-blocking layer formed on a semiconductor substrate, an edge-emitting light-emitting diode having a light-emitting portion and an absorbing portion, in the current-blocking layer, continuously or intermittently. An inverted trapezoidal first groove and a bottom surface are formed to have an inverted trapezoidal second groove smaller than the first groove, and the light emitting portion is formed in the first groove and the second trapezoidal groove. The above-described absorbing portion is formed in a groove, and the manufacturing method is an edge-emitting type in which a light emitting portion and a light absorbing portion are formed by a liquid phase growth method in a current block layer formed on a semiconductor substrate. Forming a first groove having an inverted trapezoidal shape and a second groove having an inverted trapezoidal shape whose bottom surface is smaller than the first groove in the current blocking layer continuously or intermittently; Forming the light emitting portion in the first groove; Sometimes, in the second groove, the absorber, in which a step of forming by utilizing the difference in liquid-phase growth rates due to the difference of the groove shape.

(Operation)

In the present invention, a first groove and a second groove are formed,
By utilizing the difference in the liquid phase growth rate due to the difference in the shape of these grooves, the absorption portion is formed thick in the second groove having a small bottom surface, so that a sufficient light absorption effect can be obtained even with a short absorption portion. Further, at this time, since the absorbing section is formed simultaneously with the light emitting section, the number of steps is not increased.

〔Example〕

One embodiment of the edge emitting light emitting diode of the present invention and a method for manufacturing the same will be described with reference to FIGS. still,
FIG. 1 is a side view of an edge-emitting light emitting diode, FIG. 2 is another side view of the same, FIG. 3 is a sectional view taken along the line BB of FIG. 2, and FIG. Show.

That is, the edge emitting light emitting diode is formed by sequentially stacking a p-type InP buffer layer 22 and an n-type I
an nP current blocking layer 23 and a p-type InP current blocking layer 24,
The p-type InP buffer layer 22 and the p-type InP current block layer 23
And a U-shaped U-shaped groove 27 and a V-shaped V-shaped groove 30 continuously formed in the p-type InP current blocking layer 24, and a bottom of the U-shaped groove 27;
A p-type InP cladding layer 31 and a p-type InGaAsP active layer 32 sequentially formed by liquid phase epitaxy on the bottom of the V-groove 30 and the p-type InP current blocking layer 24; A p-type InGaAsP absorption layer 33 formed on the layer 31;
The n-type I formed on the p-type InGaAsP active layer 32 at and near the groove 27 and on the p-type InGaAsP absorption layer 33 at and near the V-groove 30
An nP cladding layer 34, an n-type InGaAsP contact layer 35 formed on the n-type InP cladding layer 34, and a stripe-shaped window 37 opened directly above the U groove 27 formed on the n-type InGaAsP contact layer 35. SiO ₂ film 36, AuZn electrode 38 formed on the back surface of p-type InP substrate 21, and n-type InGa including SiO ₂ film 36
AuGeNi electrode 39 formed on AsP contact layer 35 and U
A dielectric film (not shown) which is a non-reflective film of light coated on the end face formed by cleavage of the groove 27 and the V groove 30
It is composed of Thus, in such a light emitting diode, the p-type InGaAsP active layer 32 in the U-groove 27 is energized through the stripe-shaped window 37 of the SiO ₂ film 36 to serve as a light-emitting portion, and the V-groove 30
The p-type InGaAsP adsorption layer 33 inside serves as a light absorbing portion. Also, V
The p-type InGaAsP absorption layer 33 on the groove 30 is formed on the p-type InGaA
Since the growth rate is higher than that of the sP active layer 32, the sP active layer 32 is formed in a thick film.

Next, a method for manufacturing an edge emitting light emitting diode will be described.

First, on a p-type InP substrate 21 having a Zn concentration of 4 × 10 ¹⁸ cm ^-3 ,
A p-type InP buffer layer 22 having an n concentration of 1 × 10 ¹⁸ cm ⁻³ and a film thickness of 1 μm, and an n-type InP buffer having a Sn concentration of 7 × 10 ¹⁷ cm ⁻³ and a film thickness of 0.5 μm.
The current blocking layer 23 and the Zn concentration are 7 × 10 ¹⁷ cm ⁻³ and the film thickness is 1.
A 5 μm p-type InP current blocking layer 24 is sequentially grown at a temperature of about 600 ° C. by a liquid phase growth method. Next, for example, an SiO ₂ film 25 is formed on the p-type InP current block layer 24 by the CVD method.
Approximately 000 mm thick. Then, the (110) of the wafer is deposited on the SiO ₂ film 25 by photolitho etching.
A 150 μm-long striped window 26 extending in the direction is formed (FIG. 4a).

Subsequently, using the SiO ₂ film 25 as a mask, Ar gas and Cl
Using a gas as a reactive gas, reactive ion etching is performed to form a U-shaped U-shaped groove 27 reaching the p-type InP buffer layer 22 on the wafer, and then the entire surface of the SiO ₂ film 25 is removed ( Fig. 4b).

Next, the surface of the U-groove 27 and the p-type InP current blocking layer 2
4 is coated with a SiO ₂ film 28 by CVD at a thickness of about 1500 mm. Then, by photolithography and etching technology, SiO ₂
A stripe window 29 having a length of 350 μm is formed in the film 28 so as to be continuous with the U groove 27 and extend in the (110) direction of the wafer (FIG. 4c).

Thereafter, using the SiO ₂ film 28 as a mask, wet etching with hydrochloric acid and phosphoric acid is performed to form a V-shaped V groove 30 reaching the p-type InP buffer layer 22 on the wafer. In this case, the V-groove 30 and the U-groove 27 need not necessarily be in contact with each other, and may be formed at separate positions. Then, the SiO ₂ 28 is entirely removed (FIG. 4d).

Thereafter, a double hetero layer as described below is grown and formed by a liquid phase growth method at a temperature of about 600 ° C. That is, the above U
The bottom of the groove 27 and the V-groove 30, respectively, and the p-type InP current blocking layer 2.
4, a p-type InP cladding layer 31 having a Zn concentration of 7 × 10 ¹⁷ cm ⁻³ and a p-type InGaAs having a ZnS concentration of 1 × 10 ¹⁸ cm ⁻³ and a thickness of 0.2 μm.
A P active layer 32 and a 0.6 μm thick p-type InGaAsP absorption layer 33 are sequentially deposited. At this time, p on the V-groove 30
The p-type InGaAsP active layer 32 on the U-groove 27
Since the growth rate is higher, a thick film is formed. Further, an n-type InP cladding layer 3 having a Sn concentration of 7 × 10 ¹⁷ cm ⁻³ is formed on the substrate 21.
Deposit 4 After that, an n-type InGaAsP contact layer 35 having a Sn concentration of 2 × 10 ¹⁸ cm ⁻³ is laminated on the n-type InP cladding layer 34. Next, a 1500-nm thick SiO ₂ film 36 is coated on the n-type InGaAsP contact layer 35 by the CVD method. After that, the U-groove 27 of the SiO ₂ film 36 is formed by photolitho etching.
Immediately above, after opening a striped window 37 having a width of 20 μm and a length of 150 μm, an AuZn electrode 28 is deposited on the back surface of the p-type InP substrate 21 and SiO ₂ including an exposed surface of the n-type InGaAsP contact layer 35 is formed. An AuGeNi electrode 39 is deposited on the film. Finally, a nitride film (not shown), for example, is coated as a dielectric film for suppressing laser oscillation at the end faces of the U-groove 27 and the V-groove 30 by cleavage, and is completed (FIGS. 1 and 2). , FIG. 3).

〔The invention's effect〕

As described above, according to the present invention, by utilizing the difference in the liquid phase growth rate due to the difference in the shape of the first groove and the second groove, the light-emitting portion is formed, and at the same time, the inside of the second groove having a small bottom surface is formed. To
Since the absorbing portion is formed thick, a high light absorbing effect can be easily obtained without lengthening the absorbing portion. Therefore, the above-described problem can be solved by effects such as promotion of high-density elements.

[Brief description of the drawings]

1 to 4 show an embodiment according to the present invention. FIG. 1 is a side view of a light emitting diode, FIG. 2 is another side view of the same, and FIG. B sectional view, FIG. 4 is a perspective view of the manufacturing process of the light emitting diode, FIGS. 5 to 7 show a conventional example, FIG.
FIG. 6 is a side view of the same, and FIG. 7 is a sectional view taken along line AA of FIG. 21 ... p-type InP substrate, 22 ... p-type InP buffer layer, 23 ...
n-type InP current blocking layer, 24 p-type InP current blocking layer, 27 U-groove, 30 V-groove, 31 p-type InP cladding layer, 32 p-type InGaAsP active layer, 33 p-type InGaAsP absorption layer, 34 ...... n-type InP cladding layer, 35 ...... n-type InGaAsP contact layer, 36 ...... SiO ₂ film, 37 ...... stripe windows, 38 ...
... AnZn electrode, 39 ... AuGeNi electrode.

Claims (2)

(57) [Claims] An edge emitting light emitting diode having a light emitting portion and an absorbing portion in a current blocking layer formed on a semiconductor substrate, wherein the current blocking layer has an inverted trapezoidal first or continuous shape. Forming a second groove having an inverted trapezoidal shape whose bottom and bottom are smaller than the first groove, forming the light emitting section in the first groove, and forming the absorption section in the second groove. An edge-emitting light emitting diode characterized by having a portion formed. 2. A method of manufacturing an edge-emitting light emitting diode in which a light emitting portion and a light absorbing portion are formed by a liquid phase growth method in a current blocking layer formed on a semiconductor substrate. Alternatively, the inverted trapezoidal first groove and the inverted trapezoidal second groove whose bottom face are smaller than the first groove are intermittently formed.
Forming the light emitting portion in the first groove and, simultaneously, forming the absorbing portion in the second groove in the liquid phase growth rate due to the difference in the groove shape. Forming the edge-emitting light emitting diode.