JP2815115B2 - Light emitting device and manufacturing method thereof - Google Patents

Description

The present invention relates to a light emitting device and a method for manufacturing the same, and more particularly, to a light emitting device having a plurality of light emitting portions and a method for manufacturing the same.

INDUSTRIAL APPLICABILITY The present invention is suitably used for semiconductor lasers, LEDs, and the like that emit light of a plurality of different or the same wavelengths.

[Conventional technology]

2. Description of the Related Art Conventionally, when performing optical wavelength division multiplexing communication in which a large amount of information is transmitted simultaneously by transmitting light of different wavelengths to one fiber, a light emitting element of the same number as the number of wavelengths to be transmitted is required as a transmission unit. Further, in order to transmit the light from the plurality of light emitting elements to one fiber, it is necessary to use an optical multiplexer (FOP, Vol. 4, No. 7, P45, 1979, Keiki Kojima, etc.) for coupling the light. Was. Then, the plurality of light emitting elements and the optical multiplexer are coupled with high precision so as to reduce optical loss.

[Problems to be solved by the invention]

However, in the above-described conventional technology, a plurality of light emitting elements and optical multiplexers are manufactured and then arranged with high accuracy, and thus have the following problems.

Since a plurality of light emitting elements and an optical multiplexer are provided, the size of the transmitting unit is increased.

The coupling between the light emitting element and the optical multiplexer and the coupling between the optical multiplexer and the fiber are required, and the presence of a plurality of mechanical couplings increases the coupling loss as a whole, resulting in poor efficiency.

The process is complicated because a plurality of elements are independently manufactured and combined.

Because it requires many elements and the process is complicated,
The cost is high.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a compact and efficient light emitting device which can be manufactured at low cost and a method for manufacturing the same.

[Means for solving the problem]

The light emitting device according to the present invention includes a substrate, a first cladding layer formed on a part of the substrate, and an outer peripheral portion of the first cladding layer on the substrate. A first active layer that emits light, a second cladding layer formed on the outer periphery of the first active layer on the base, and an insulation formed on the outer periphery of the second cladding layer on the base. Alternatively, a high-resistance layer, a third cladding layer formed on the outer periphery of the insulating or high-resistance layer on the base, and an outer periphery of the third cladding layer on the base are injected with current. A second active layer that emits light, a fourth cladding layer formed on the outer periphery of the second active layer on the base, and a current supply to the first and second active layers. Wherein the first active layer, the first and second cladding layers are provided on the surface of the base. Forming a first double heterostructure having a substantially vertical bonding surface, wherein the second active layer, the third and the fourth cladding layers have a second double heterostructure having a bonding surface substantially perpendicular to the surface of the substrate. It is characterized by constituting a hetero structure.

In addition, the method for manufacturing a light-emitting device of the present invention has a structure in which a part of the surface of the base has a higher nucleation density than other parts, and a crystal grows on this part from only a single nucleus. Forming a nucleation surface having a small area, growing a first cladding layer made of a single crystal semiconductor from a single nucleus in a minute region on the substrate including the nucleation surface, A process of growing a first active layer made of a single crystal semiconductor on an outer peripheral portion of one clad layer, and a process of growing a second clad layer made of a single crystal semiconductor on an outer peripheral portion of the first active layer on the substrate. A step of growing an insulating or high-resistance layer made of a single-crystal semiconductor on an outer peripheral portion of the second cladding layer on the base, and a step of growing a single-crystal semiconductor on the outer peripheral portion of the insulating or high-resistance layer on the base. Growing a third cladding layer; Growing a second active layer made of a single crystal semiconductor on an outer peripheral portion of the upper third clad layer, and forming a fourth clad layer made of a single crystal semiconductor on an outer peripheral portion of the second active layer on the substrate Growing the first and second active layers, the first to fourth cladding layers, and insulating or high-resistance layers, and the first and second active layers. Forming an electrode for supplying current to the first active layer, the first and second cladding layers, the first active layer, the first and second cladding layers having a junction surface substantially perpendicular to the surface of the substrate. A structure, wherein the second
The third active layer, the third and fourth cladding layers constitute a second double heterostructure having a bonding surface substantially perpendicular to the surface of the base.

[Action]

A non-nucleation surface having a low nucleation density and a nucleation surface having an area small enough for crystal growth than a single nucleus and having a nucleation density higher than the nucleation density of the non-nucleation surface are arranged adjacent to each other. A method for forming a single crystal by subjecting a substrate having a free surface to a crystal shape treatment has already been disclosed in
No.-723 discloses a crystal formation method capable of growing a single crystal at a desired position on a desired base substrate with a nucleation surface as a center.

The present invention has a plurality of double heterostructures by changing manufacturing conditions of a single crystal material, a composition ratio, an impurity material, and the like at the stage of growing a single crystal using such a crystal formation method, and A single crystal having an insulating layer or a high resistance layer between the double hetero structure portions is grown, and the single crystal is flattened to expose a plurality of double structure portions, thereby forming a plurality of light emitting portions.

In the present invention, the reason why the insulating layer or the high resistance layer is provided between the double hetero structure portions is to prevent a current leaking to an adjacent double hetero structure portion when a current is injected into a desired double hetero structure portion. . That is, with such a configuration, the light-emitting element of the present invention achieves the above-described object, and can emit light with higher efficiency and less noise.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, an embodiment of the light emitting device of the present invention and a manufacturing method thereof will be described.

FIG. 1 is a plan view and a longitudinal sectional view showing the structure of a first embodiment of the light emitting device of the present invention, and FIGS.
(E) is a process drawing showing the manufacturing process.

First, as shown in FIG. 2A, the surface of an amorphous substrate 10 such as SiO ₂ , Al ₂ O ₃ is defined as a non-nucleation surface 2.
A nucleation surface 1 is formed by forming a fine deposited film thereon.

Next, as shown in FIG. 2 (b), by utilizing the difference in nucleation density between the non-nucleation surface 2 and the nucleation surface 1, selective metalorganic vapor phase epitaxy (MOCVD) is used. GaAs on nucleation surface 1
A single crystal grain 7 is formed. Growth is trimethylgallium (TM
It performed using raw materials such as G) tertiary butyl arsine (TBAs) AsH _3. The growth temperature is generally from 500 to 800 ° C, preferably from 570 to 760 ° C, most preferably from 600 to 700 ° C, and the pressure is generally from 1 to 80 Torr, preferably from 1 to 30 Torr, most preferably from 1 to 10 Torr.

Next, as shown in FIG.
~ 760 Torr, preferably 100 ~ 760 Torr, optimally 300 ~ 76
Change to 0 Torr, increase the supply amount of raw material, add Al raw material such as trimethyl aluminum (TMAl), and add cladding layer 3a, active layer 4a, cladding layer 3b, high resistance layer 8, cladding layer 3c, active layer 4b, cladding layer 3d is sequentially formed.

Here, the growth method is not limited to the MOCVD method, and a gas source molecular beam growth method (gas source MBE method) or a liquid phase growth method (LPE method) may be used. The single crystal formed here may be another III-V compound semiconductor such as InP.

Next, as shown in FIG. 2 (d), the crystal surface is flattened to expose the clad layer 3a, the active layer 4a, the clad layer 3b, the high resistance 8, the clad layer 3c, the active layer 4b, and the clad layer 3d. .

Next, as shown in FIG. 2 (e), the electrode layer 5 is formed on the exposed clad layers 3a, 3b, 3c, 3d of the formed single crystal layer, and the clad layers 3a, 3b, 3c, 3d are formed. The electrode wirings 6a, 6b, 6c, 6d are connected to the respective electrode layers above.

Thus, the light emitting device according to the present invention shown in FIG. 1 can be manufactured. The active layers 4a and 4b of the manufactured light emitting device have a polygonal shape as shown in the plan view of FIG. 1, and light is emitted from the active layers 4a and 4b. The wavelength of light emitted from the active layers 4a and 4b can be arbitrarily set by changing the introduced single crystal material, composition ratio, and the like, and can be the same wavelength.

FIG. 3 is a plan view and a longitudinal sectional view showing the structure of a second embodiment of the light emitting device of the present invention, and FIGS.
(E) is a process drawing showing the manufacturing process.

First, as shown in FIG. 4A, a layer for forming the non-nucleation surface 12 such as SiO ₂ is formed on a support substrate 19 such as Al ₂ O ₃ . Then, impurity ions are implanted into this layer, and the nucleation surface
Form 11.

Next, as shown in FIG. 4 (b), the nucleation density of the non-nucleation surface 12 and the nucleation surface 11 is calculated in the same manner as in the first embodiment already described with reference to FIG. 2 (b). Utilizing the difference, GaAs single crystal grains 7 are selectively formed on the nucleation surface 11 by using a metal organic chemical vapor deposition (MOCVD) method. Growth is trimethylgallium (TMG), tert-butylarsine (TBAs) A
carried out using raw materials such as sH _3. Growth temperature is generally 500
~ 800 ℃, preferably 570 ~ 760 ℃ and optimally 600 ~ 700 ℃
The pressure is generally 1 to 80 Torr, preferably 1 to 30 Torr.
Torr, optimally at 1-10 Torr.

Next, as shown in FIG. 4 (c), in the same manner as in the first embodiment already described with reference to FIG. 2 (c), the pressure is generally 50 to 760 Torr, preferably 100 to 760 Torr. To 300 to 760 Torr, increase the supply of raw materials, add an Al raw material such as trimethyl aluminum (TMAl), and add cladding layer 13a, active layer 14a, cladding layer 13b, high resistance layer 18a, cladding layer 13c, and active layer. 14b, cladding layer 13d, high resistance layer 18b,
A clad layer 13e, an active layer 14c, and a clad layer 13f are sequentially formed.

The crystal growth method is not limited to the MOCVD method.
The semiconductor material other than s may be the same as in the first embodiment.

Next, as shown in FIG. 4 (d), the crystal surface is flattened, and the cladding layer 13a, the active layer 14a, the cladding layer 13b, the high-resistance layer 18a, the cladding layer 13c, the active layer 14b, the cladding layer 13d,
High resistance layer 18b, cladding layer 13e, active layer 14c, cladding layer 1
Expose 3f.

Next, as shown in FIG. 4 (e), an electrode layer 15 is formed on the exposed clad layers 13a, 13b, 13c, 13d, 13e, 13f of the formed single crystal layer, and the clad layers 13a, 13b are formed. , 13c, 13d, 13e, 13
The electrode wirings 16a, 16b, 16c, 16d, 1
Connect 6e and 16f.

Thus, the light emitting device according to the present invention shown in FIG. 3 can be manufactured. The active layers 14a, 14b, 14c of the manufactured light emitting device have a polygonal shape as shown in the plan view of FIG. 3, and light is emitted from the active layers 14a, 14b, 14c. The wavelength of the light emitted from the active layers 14a, 14b, and 14c can be arbitrarily set by changing the single crystal material to be introduced, the composition ratio, and the like. It is also possible.

Hereinafter, an example related to the above-described embodiment will be described.

(Example 1) This example relates to the first embodiment example, and
A semiconductor laser having two active layers of -GaAs and i-Ga _0.9 Al _0.1 As was manufactured. The structure and manufacturing process of the semiconductor laser will be described with reference to FIGS.

As shown in FIG. 2 (a), Al ₂ O ₃ is vapor-deposited on the SiO ₂ substrate as the amorphous substrate 10, leaving a fine region (1.2 μm square), and removing the others by etching to obtain a non-nucleus. A formation surface (SiO ₂ ) 2 and a nucleation surface (Al ₂ O ₃ ) 1 are formed.

Next, as shown in FIG.
00 ° C, carrier gas flow rate (H ₂ ) 3 / min, tertiary butyl arsine (TBAs) as raw material source 3 × 10 ^-4 mo
l / min, trimethylgallium (TMG) 3 × 10 ^-5 mol / mi
n, trimethylaluminum (TMAl) at 1 × 10 ^-5 mol / min,
Using diethyl zinc (DEZn) as a doping material,
The single crystal grains 7 as p-Ga _0.75 Al _0.25 As single crystal grains are nucleated.

Next, as shown in FIG. 2 (c), the growth temperature was 600 ° C., the carrier gas flow rate was 10 / min, the pressure was 100 Torr by MOCVD.
A group III-V compound semiconductor material (V / III ratio = 50), arsine (AsH ₃ ), TMG, TMAl is used as a raw material source, and DEZn and silane (SiH ₄ ) are used as a doping raw material. Then, by switching the material source and the doping material, the p-Ga _0.75 Al _0.254 As clad layer as the clad layer 3a, the i-GaAs active layer as the active layer 40, and the n-Ga _{0.75 as the} clad layer 3b are formed.
Al _0.25 As clad layer, high resistance layer 8 i-Ga _0.7 Al _0.3 As
A high resistance layer, an n-Ga _0.75 Al _0.25 As clad layer as a clad layer 3c, an i-Ga _0.9 Al _0.1 As active layer as an active layer 4b, and a p-Ga _0.75 Al _0.25 As clad layer as a clad layer 3d are grown.

Next, as shown in FIG. 2 (d), the crystal surface was flattened by RIBE, and a p-Ga _0.75 Al _0.25 As clad layer as a clad layer 3a, an n-Ga _0.75 Al _0.25 As clad layer as a clad layer 3b, cladding layer 3c serving n-Ga _0.75 Al _0.25 as cladding layer, the cladding layer 3d serving to expose the p-Ga _0.75 Al _0.25 as cladding layer, as shown in more second view (e), the electrode layer 5 on the exposed surface A conductive laser layer is formed, and the conductive layer is connected to electrode wirings such as Au serving as the electrode wirings 6a, 6b, and 6c, respectively, to manufacture a semiconductor laser.

In the semiconductor laser fabricated as described above, the threshold current of the i-GaAs active layer as the active layer 4a was measured at room temperature pulse operation.
A semiconductor laser having a threshold current of 200 mA and a threshold current of the active layer 4b of -Ga _0.9 Al _0.1 As active layer of 410 mA is obtained.

(Example 2) This example is related to the second embodiment example, and i
An LED having three active layers of -GaAs, i-Ga _0.95 Al _0.05 As and i-Ga _0.9 Al _0.1 As was produced. Since the structure and manufacturing process of the LED are the same as those of the light emitting device described with reference to FIGS. 3 and 4, the description will be made with reference to FIGS. 3 and 4.

As shown in FIG. 4 (a), a SiO ₂ layer for forming the non-nucleation surface 12 is deposited on a ceramic substrate as a support substrate 19, and As ions are implanted into a fine region (1.2 μm square) to reduce the nucleation density. Raised to form the nucleation surface 11.

Next, as shown in FIG. 4 (b), a growth temperature of 600 ° C. and a III-V compound semiconductor material (V / III ratio) = 1 by MOCVD.
0, pressure 10 Torr, using TBAs, TMG, a TMAl as a raw material source, a single crystal grain 17 serving n-Ga _0.8 Al _0.2 As the single crystal grain nuclei formed using SiH ₄ as a raw material for doping.

Next, as shown in FIG. 4 (c), by MOCVD method, using AsH ₃ , TMG, TMAl as source material, DEZn, SiH ₄ as dope source at a growth temperature of 600 ° C., V / III ratio = 50, pressure of 100 Torr, By switching the material source and the doping material, the n-Ga _0.8 Al _0.2 As clad layer 13a serving as the clad layer 13a and the active layer 1 are formed.
4a, i-GaAs active layer as a clad layer, p-Ga _0.8 Al as a clad layer 13b
_0.2 As clad layer, i-Ga _0.7 Al _0.3 As high resistance layer 18a, i-Ga _0.7 Al _0.3 As high resistance layer, clad layer 13c p-Ga _0.8 Al _0.2 As clad, active layer 14b i-Ga _0.95 Al _0.05 As active layer, clad layer 13d n-Ga _0.8 Al _0.2 As clad layer, high resistance layer 18b
Barrel i-Ga _0.7 Al _0.3 As high resistance layer, cladding layer 13e barrel p
-Ga _0.8 Al _0.2 As clad layer, active layer 14c, i-Ga _0.9 Al
_An n-Ga _0.8 Al _0.2 As clad layer serving as a _0.1 As active layer and a clad layer 13f is grown.

Next, as shown in FIG. 4 (d), the surface is flattened by RIBE, and an n-Ga _0.8 Al _0.2 As clad layer as a clad layer 13a, a p-Ga _0.8 Al _0.2 As clad layer as a clad layer 13b,
Cladding layer 13c serving p-Ga _0.8 Al _0.2 As cladding layer, the cladding layer 13d serving n-Ga _0.8 Al _0.2 As cladding layer, the cladding layer 13e serving p-Ga _0.8 Al _0.2 As cladding layer, the cladding layer 13f
The n-Ga _0.8 Al _0.2 As clad layer is exposed, and a conductive layer as an electrode layer 15 is formed as shown in FIG. 4 (e). Electrode wirings 16a, 16b, 16c, 16d are formed on the conductive layer, respectively. , 16
e, LED electrodes are made by connecting electrode wirings such as 16f Au.

The light emitting device manufactured as described above was grounded at room temperature with a pulsed operation at room temperature, and the electrode wiring on the n-Ga _0.8 Al _0.2 As clad layer 13d was grounded, and 100 mA was applied to the active layer 14b, i-Ga _0.95 Al _0.05 As active layer. When current was injected, the intensity ratio of the light output to the other active layers became -20 dB.

〔The invention's effect〕

As described above in detail, according to the present invention, by forming an insulating layer or a high-resistance layer between each double hetero structure portion, it is possible to reduce leakage current to other than the intended double hetero structure portion, As a result, the threshold value of the semiconductor laser can be reduced, and light emission from portions other than the target double hetero structure portion can be prevented.

Further, since the present invention can be manufactured by an ordinary semiconductor process, it can be manufactured without requiring a special device and without complicating a manufacturing process.

[Brief description of the drawings]

FIG. 1 is a plan view and a longitudinal sectional view showing the structure of a first embodiment of the light emitting device of the present invention. 2 (a) to 2 (e) are process diagrams showing the manufacturing process of the first embodiment. FIG. 3 is a plan view and a longitudinal sectional view showing the structure of a second embodiment of the light emitting device of the present invention. FIGS. 4 (a) to 4 (e) are process diagrams showing the manufacturing process of the second embodiment. 1,11… nucleation surface, 2,12… non-nucleation surface, 3a, 3b, 3c, 3d,
13a, 13b, 13c, 13d, 13e, 13f …… cladding layers, 4a, 4b, 14a, 1
4b, 14c: Active layer, 5, 15: Electrode layer, 6a, 6b, 6c, 6d, 16a,
16b, 16c, 16d, 16e, 16f: electrode wiring, 7, 17: single crystal grain, 8, 18a, 18b: high resistance layer.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) H01S 3/18 H01L 33/00

Claims (4)

(57) [Claims] A first substrate formed on a part of the substrate;
A first active layer formed on an outer peripheral portion of the first clad layer on the substrate and emitting light by current injection, and an outer peripheral portion of the first active layer on the substrate A second cladding layer formed on the substrate, an insulating or high-resistance layer formed on the outer periphery of the second cladding layer on the substrate,
A third cladding layer formed on the outer periphery of the insulating or high-resistance layer on the base and a third cladding layer formed on the outer periphery of the third cladding layer on the base and emitting light by current injection; A second active layer, a fourth cladding layer formed on an outer peripheral portion of the second active layer on the base, and the first and second active layers.
And an electrode for supplying a current to the active layer, wherein the first active layer, the first and second cladding layers have a first double heterostructure having a bonding surface substantially perpendicular to the surface of the base. Wherein the second active layer, the third and the fourth cladding layers constitute a second double heterostructure having a junction surface substantially perpendicular to the surface of the base. 2. The substrate has a non-nucleation surface having a low nucleation density, a nucleation density higher than the specific nucleation surface, and a crystal on which only single nuclei grow. A nucleation surface disposed adjacent to said non-nucleation surface having a sufficiently small area, wherein said first cladding layer is formed in a small area on a substrate including said nucleation surface. 1
A light-emitting device according to claim 1. 3. The light emitting device according to claim 1, wherein said first and second active layers emit light having different wavelengths from each other. 4. A nucleation surface having a greater nucleation density on one portion of the surface of the substrate than on the other portion and having a sufficiently small area thereon that crystals grow from only a single nucleus. Forming a first cladding layer made of a single crystal semiconductor from a single nucleus in a minute region on the substrate including the nucleation surface; and forming an outer peripheral portion of the first cladding layer on the substrate. Growing a first active layer made of a single crystal semiconductor on the substrate, growing a second cladding layer made of a single crystal semiconductor on the outer periphery of the first active layer on the substrate, Growing an insulating or high-resistance layer made of a single-crystal semiconductor on the outer periphery of the second cladding layer, and growing a third cladding layer of a single-crystal semiconductor on the outer periphery of the insulating or high-resistance layer on the substrate And forming a third cladding layer on the substrate. Growing a second active layer made of a single crystal semiconductor on a peripheral portion, growing a fourth cladding layer made of a single crystal semiconductor on an outer peripheral portion of the second active layer on the base; First and second active layers,
A step of flattening the upper portions of the first to fourth cladding layers and the insulating or high-resistance layer, and a step of forming electrodes for supplying current to the first and second active layers. The first active layer, the first and second cladding layers constitute a first double heterostructure having a bonding surface substantially perpendicular to the surface of the base, and the second active layer, the third and fourth cladding layers. A method for manufacturing a light-emitting device in which a cladding layer has a second double heterostructure having a bonding surface substantially perpendicular to a surface of the base.