JPS6272190A - Manufacture of semiconductor laser - Google Patents

Abstract

PURPOSE:To form a semiconductor laser of a buried structure simply and with high accuracy by a method wherein, after converged ion beam of an impurity is applied to the predetermiend positions of an active layer or a optical waveguide layer, a high temperature heat treatment is performed for several hours. CONSTITUTION:An N-type Ga1-xAlx layer 2 of about 3mum thickness is made to grow on an N-type GaAs substrate crystal 1 by epitaxial growth. Then an undoped GaAs-Ga1-xAlxAs quantum well active layer 3 is made to grow. A P-type Ga1-xAlxAs layer 4 of about 0.2mum thickness,which is an optical waveguide layer, and an N-type GaAs-Ga1-xAlxAs quantum well layer 5 are made to grow on the active layer 3. Growth is discontinued at this state and Be ions are implanted into the stripe patterns in the center part of the multilayer quantum well 5 on the optical waveguide layer. Then a P-type Ga1-xAlxAs layer 6 of about 1mum thickness is made to grow on the quantum well layer 5 and further a P-type GaAs layer 7 of about 1mum thickness is made to grow on the layer 6. The crystal layers formed as described above are subjected to a heat treatment in an atmosphere of pressurized As at 675 deg.C for four hours by a closed tube method.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention has a multi-V well with a high refractive index of 4% inside! The present invention relates to a method for manufacturing a semiconductor laser device having a buried structure, which has an active layer or an optical waveguide layer, and whose left and right sides are surrounded by the averaged composition of the multi-ff1ffl child well structure having a low refractive index; In particular, the present invention relates to a method for easily and accurately manufacturing a distributed feedback buried heterostructure semiconductor laser device.

(Prior art) Min! +Feedback buried heterostructure laser devices are known as semiconductor radar devices that can oscillate a single laser beam in both longitudinal and transverse modes.

As shown in Figure 2, its structure is an optical waveguide P:! with a multi-hair quantum well structure, which is constructed by alternately stacking three or more ultra-thin films of two types of compounds and conductors. A semiconductor layer with a wide forbidden band width is already embedded on the left and right sides of the optical waveguide layer a, and a diffraction grating C is provided in the optical waveguide layer a.

Conventionally, such a distributed feedback buried heterostructure laser device has been manufactured by chemical engineering using optical drying, etc.; Grow a double heterostructure crystal using liquid phase growth method,
After this crystal is formed into a mesa stripe shape by chemical etching, the mesa stripe is filled with a semiconductor layer having a wide forbidden band width by a second liquid phase growth.

(IFI + problem that civilization is trying to solve) However, the above manufacturing method is complicated and requires advanced technology, so (1) it is difficult to control the stripe width by chemical etching; (2) Situations such as buried growth not working well, (3) diffraction gratings not being properly formed on the substrate crystal, and (4) the created diffraction gratings breaking during liquid phase growth often occur, resulting in poor product yields.

(Means for Solving the Problems) In order to solve the above problems, the present invention uses a multi-quantum well structure in which two types of compound semiconductor ultrathin films having different compositions are alternately stacked in three or more layers as an active layer. Alternatively, in a method for manufacturing a conductor laser device in which the active layer or the right and left sides of the optical waveguide layer are made of semiconductors having an average composition of the layers, the above formula h' is applied to the conductor pole f. Impurities are mixed into the film so that the multi-quantum well structure is broken by heat treatment and the composition becomes the average composition of the two types of compound semiconductors, and furthermore, in the active layer or the optical waveguide layer, the part that requires the multi-quantum well structure is mixed with an impurity. In this method, a focused ion beam of a different kind of impurity is implanted so that the multi-quantum well structure remains intact during heat treatment regardless of the existence of the impurity listed in L, and the part where the ion beam was implanted is left after heat treatment. The composition of the active layer or optical waveguide layer is averaged.

Here, the active layer or the optical waveguide layer is composed of two types of compound semiconductor electrodes with different Mi compositions, such as a GaAs layer and a GaAlAs layer. A multi-quantum well structure is constructed by alternately stacking three or more layers of membranes.

In addition, examples of impurities that mix into the compound semiconductor ultrathin film and destroy the multi-quantum well structure due to heat treatment include Si.
etc. can be mentioned.

Furthermore, Ue'4 can be cited as another type of impurity that allows the multi-quantum well structure to remain unbroken during heat treatment regardless of the presence of the above-mentioned impurities.

These different types of impurity focused ion beams are not implanted into the left and right regions of the active layer or optical waveguide layer in order to form a semiconductor laser with a buried structure. Type in the part that needs to be left 0
For example, in the case of a semiconductor laser having a distributed feedback buried structure, the laser beam is implanted so that a striped pattern is formed along the longitudinal direction of the optical waveguide layer.

After a focused ion beam of impurities is injected into a predetermined location of the active layer or optical waveguide layer, heat treatment is performed at a high temperature of about 600 to 800° C. for several hours using, for example, the As pressure closed tube method.

(Function) When the heat treatment described in 1. Although the composition has a low refractive index, the multiple quantum well structure with a high refractive index remains unbroken despite the presence of impurities such as Sl in the part where a focused ion beam of a pure substance such as Be is implanted. It has an active layer or optical waveguide layer with a multi-hair quantum well structure with a high refractive index in the center, and the left and right sides are surrounded by an averaged composition of the Kidahigashi quantum well structure. A semiconductor laser can be easily created.

In addition, in this invention, a focused ion beam is used to selectively create the multi-hair quantum well structure region and its average composition structure region, which will become the active layer or the leading wave layer. The width can be controlled with a precision of 14 mm, resulting in low agony current.

Moreover, it becomes possible to manufacture a laser device in which the transverse mode of light is controlled.

Similarly, in the present invention, a multi-quantum well structure with a high refractive index is used in the active layer region or the leading wavefront region.

Since the average composition structure with a low refractive index can be provided periodically with high precision, a distributed feedback laser device with good longitudinal mode control can be easily produced.

Further, in this invention, by using a focused ion beam, chemical etching is not necessary and crystals can be grown in multiple layers.

(Example) The present invention will be explained below based on illustrated embodiments.

Figure 1 shows the application of this invention to the manufacture of a distributed feedback semiconductor laser device.
s substrate crystal 1 (Si doped, carrier concentration: 2
lot"Cm-]) on the n-Ga1xAIxAs layer 2 (!=0.4, Si doped, carrier concentration: I
0-order undoped GaAs-Ga1-xAlxAs grown epitaxially in 3 pots (1018cm-')
P well active layer 3 (GaAs layer 2 thickness 100 layers 4 layers, Ga1-xAlxAs layer: x-0,2, H 6
0 people, 3 layers) to 1 & length. On top of this is a P-Gal-xAlxAS layer 4 (x-0,3, Be
Dope, carrier concentration: l x 1018 cm-3
) to 0.2l1 and n-GaAs-Ga+-xAlx
As u well layer 5 (Si doped, carrier concentration:
I X 1011018a, GaAs layer: 80 people 1
0 layer, Ga1-xAlx As layer: x=0.5,120
Develop people (9 layers).

After the growth is started here, the crystal is transferred to a focused ion beam implanter which is connected to a 7-line growth device in an ultra-high vacuum, and Be ions are implanted at a dose of 2×1014.
cm? , acceleration voltage 200Xe and beam diameter 0.1 g
A striped pattern was implanted into the center of the multiple quadruple well layer 5 of the leading wave layer under the conditions of ta.

In this case, the Be implanting stripe l+1 is 3 pots, the period is 2400 people, and the length of the part with the periodic structure is 300.
p, ts, and the length of the part without periodic structure is 1
00 AL shoes.

In this way, a crystal as shown in FIG. 1a is produced.

Next, use this crystal again as a molecular beam JJ! Transfer to a l-long device, and add a P-Gal-xAlxAs layer 6 (x=0.4.
Be doped carrier concentration: I x 1013cm
-3) to IgmJ&fQ, and then P-GaA
s7 (Be doped, carrier concentration + l X10X
10l8') to l gts J& length.

The crystal thus created was heated to 67° C. with As pressure and closed tube.
Heat treatment at 5°C for 4 hours. Through this heat treatment, Si-topped n-GaAs-Ga+, xAlxAs Q well layer 5 is formed.
is broken and becomes GaAlAs with an average composition, but the quantum well structure in the Be implanted region 5a remains unbroken, and as a result, the left and right regions in the leading wave layer have a wide forbidden band width.
In addition, it is composed of a GaAlAs layer with a low average composition and a low refractive index, and has a periodic structure in the center consisting of a region with a high refractive index of a quantum well structure and a region with a low refractive index of a GaAlAs region with an average composition. A semiconductor with a feedback-type buried heterostructure has been manufactured.

Therefore, a semiconductor laser device as shown in FIG. 1b can be manufactured by forming electrodes 8.8 on both sides of this conductor and cutting it out to a length of about 400 μm and 1'11300 JLm.

In this embodiment, a method of manufacturing a distributed feedback semiconductor laser device with a buried structure has been described, but it goes without saying that the present invention can be applied to a method of manufacturing other conductor laser devices with a buried structure.

(Effects of the Invention) In summary, in the present invention, it is possible to easily manufacture a buried structure laser conductor laser device δ, especially a buried structure 7II recursive conductor laser device with high precision. .

[Brief explanation of drawings]

FIG. 1 shows an example of manufacturing a distributed feedback type buried heterostructure semiconductor laser according to the present invention. FIG. 1a is a J view showing the Be ion implantation pattern into the optical waveguide layer, and FIG. FIG. 2 is a partially cutaway perspective view showing a completed state of the semiconductor laser, and FIG. 2 is a perspective view showing a conventional semiconductor laser device with a 1i feedback type buried structure.

Claims (1)

[Claims] The active layer or optical waveguide layer is a multi-quantum well structure constructed by alternately stacking three or more layers of two types of compound semiconductor ultrathin films with different compositions, and the left and right sides of the active layer or optical waveguide layer have the average composition of the layer. In the method for manufacturing a semiconductor laser device comprising a semiconductor, an impurity is mixed into the extremely thin compound semiconductor film so that the multi-quantum well structure is broken by heat treatment and the composition becomes an average composition of two types of compound semiconductors, and an active layer is further added. Alternatively, a focused ion beam of a different type of impurity is applied to a portion of the optical waveguide layer that requires a multiple quantum well structure, so that the multiple quantum well structure remains unbroken during heat treatment regardless of the presence of the impurities. A method for manufacturing a semiconductor laser device, characterized in that the composition of the active layer or optical waveguide layer is averaged by implanting and heat-treating the active layer or optical waveguide layer while leaving a portion into which the ion beam has been implanted.