JPH04127489A - Semiconductor optical element and manufacture thereof - Google Patents

Abstract

PURPOSE:To integrate an optical element having various band gaps on the same substrate without complicating the crystal growing process by controlling the gap according to the degree of disordering of a quantum well structure. CONSTITUTION:A semiconductor optical element is used as a light emitting region 21 in a quantum well structure which is 'not disordered, a waveguide 22 is formed in a waveguide region, a phase regulating region 23, a DBR region 24 and a PM modulated region 25 are formed in a refractive index control region, and an AM modulated region 26 is formed in an absorption control region. The control region is increased in its band gap by disordering, and the absorption edge is shifted slightly to a short wavelength side from an oscillation wavelength correspondingly. Thus, the edge corresponding to the gap is shifted to a short wavelength side from the oscillation wavelength of the region 21. Accordingly, it becomes transparent in a steady state. However, when a current or a voltage is applied to the region, the edge is shifted to the long wavelength side, and its absorption coefficient is varied. The region can be used as the region 26 by using variation in the coefficient.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is applied to a semiconductor optical device using a quantum well structure. In particular, it relates to semiconductor structures surrounding quantum well structures.

〔overview〕

In a semiconductor optical device provided with a quantum well structure, the present invention makes it possible to easily fabricate a plurality of optical devices with different bandgaps by disordering the quantum well structure other than the portion used as a light emitting region and using it as a waveguide region. This allows for high coupling efficiency to be achieved.

[Prior art]

When forming various optical elements that operate in the same wavelength band on the same substrate, it is necessary to use semiconductors with different optical properties, particularly band gaps, depending on the type of optical element. Conventionally, in order to optically couple semiconductors with different band gaps on the same substrate, a method has been used in which a semiconductor thin film that has been grown as a crystal is partially etched and semiconductors with different band gaps are regrown. There is. This method is described, for example, by Shigeru Murata and Ikuo.
Mido, Coralou Kobayashi, [Spectral Characteristics for a 1.5 Immediate DBR Laser]
With Frequency Tuning Region J
, IEEE Journal of Craontum Electronics Volume QE-23, No. 6, June 1987 (S,
Murata, I., Mito and K., Koba.
Yashi.

”5pectr'al Characteristi
cs for a 1.5 Btn DBRLase
r with Frequency-Tuning
Region”, IEEE Journal
of Quantum Electronics
, VOI, QB-23°No, 6. June
(1987).

[Problem that the invention seeks to solve]

However, in the conventional method, since semiconductors with different band gaps are grown separately, it is necessary to repeat etching and crystal growth many times, and it is difficult to grow each semiconductor layer flatly. Furthermore, since the structures of the waveguides are different, it has been difficult to increase the coupling efficiency between elements.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a semiconductor optical device having a structure that is easy to manufacture and can integrate a large number of optical devices with high coupling efficiency, and a method for manufacturing the same.

[Means for solving problems]

The semiconductor optical device of the present invention includes a light emitting region formed by a quantum well structure and a waveguide region formed adjacent to the emission end of the light emitting region and having a different band gap from the light emitting region on the same substrate. The semiconductor optical device is characterized in that the waveguide region includes a disordered region in an extension of the quantum well structure.

Here, the waveguide region includes not only the guiding waveguide but also the optical coupler,
DBR (Distributed Bragg Ref.
director) area, phase adjustment area, PM modulation area, A
This refers to the M modulation region and other regions that propagate the light emitted from the light emitting region.

To manufacture such a semiconductor optical device, a quantum well structure is formed on a substrate, and at least a portion of this quantum well structure is disordered. At this time, by controlling the degree of random floating, the bandgap in that region is variably set.

To disorder the quantum well structure, heat treatment is performed after ion implantation. At this time, the degree of disorder is controlled by controlling at least one of the dose and implantation energy in ion implantation. Furthermore, the degree of disordering can also be controlled by selecting the implanted ion species.

Ion implantation is preferably performed at an early stage of the process following the growth of the quantum well structure. That is, a first growth step in which a semiconductor layer including a quantum well structure is grown on a substrate, and a second growth step in which another semiconductor layer is grown on top of this semiconductor layer to form a semiconductor laser structure. including,
It is desirable to perform ion implantation following the first growth step, and to perform the second growth step after the ion implantation is completed.

In particular, in the first growth step, the guide layer that forms the diffraction grating and rib waveguide is grown, and between the first and second growth steps, ion implantation and formation of the diffraction grating and rib waveguide are performed. This is desirable.

It is desirable that the heat treatment be performed in parallel with the formation of the semiconductor layer by increasing the temperature in the second growth step.

The region in which the quantum well structure is disordered by the above method includes a Bragg reflection region, a variable wavelength Bragg reflection region, and a resonant optical reflector.
reflector (hereinafter referred to as rRORJ), variable wavelength ROR, etc.

[For production]

As the quantum well structure becomes more disordered, the effective well width decreases, the first quantum level changes, and the bandgap increases. Complete disordering increases the bandgap to the value of the barrier layer.

Therefore, a region that is not disordered at all is used as a light emitting region, and an optical waveguide, a DBR region, a phase adjustment region, a PM modulation region, an A
M modulation areas and others are formed.

Furthermore, when ion implantation is performed between two growth steps, the distance between the ion implantation surface and the quantum well layer is small, so the dose and implantation energy can be reduced. This makes it possible to reduce absorption in the ion-implanted region.

〔Example〕

1 and 2 show a method of manufacturing a semiconductor optical device according to an embodiment of the present invention. Here, GRIN is used as a quantum well structure.
-5CH-3QW (Graded Index -S
eparateConfinement ) Iter
structure -Single Quantu
An example will be explained in which a tunable wavelength Bragg reflection laser, an AM modulator, and a PM modulator are integrated on the same substrate using a tunable Bragg reflector (mWell). In this example, disorder is controlled by the dose in the S1 ion implantation, the growth process is divided into a first and second growth process, ion implantation is performed after the first growth process, and the heating temperature in the second growth process is The case of a heat treatment process for ion implantation will be explained.

First, as shown in FIG. 1(a), a buffer layer 2, a cladding layer 3, a GRIN layer 4, an active layer 5, a GRI
The N layer 6 and the guide layer 7 are grown in order.

Here, the GRIN layer 4, the active layer 5, and the GRIN layer 6 are formed with a quantum well structure.

Next, the quantum well structure is disordered by ion implantation and heat treatment. During ion implantation, a mask 8 with a window open in a region where an optical element is to be formed is provided on the surface of the guide layer 7, and the dose is controlled according to the band gap required for the optical element.

Figure 1 et al.) to d) show a waveguide region for connecting individual optical elements, a refractive index control region for variably controlling the refraction and refractive index for synchrotron radiation, and a variable absorption coefficient for synchrotron radiation. The shape of the mask for forming the absorption coefficient control region for controlling the absorption coefficient is shown in each figure. Sl was used as the implanted ion, and the doses for each region were s, , 32, and s, respectively.

shall be. however, SL　＞32　＞33 It is.

The quantum well structure is disordered by heat treatment after ion implantation. The degree of disorder varies depending on the dose of the region. Regarding the disordering of quantum well structures by ion implantation and heat treatment, see, for example, Ueyama and Yamagawa, “Compositional Disordering of Si-Implanted GaAs/A4GaAs Superstructures with Pyramid Thermal Annealing,” Japanese Journal of・Applied Physics Vol. 26 No. 8, August 1987, No. L147
0-L1409 pages (Masashi [Jematsu
, Fumihiko Yamagawa, “Camp
ositional ordering of
5i-1+y+planted GaAs/^lGaA
s 5superlatives by Rapid T
"hermal annealing", Japan
se Journal of Applied P
hysics.

Vol, 26. No, 8. ＾gust, 1987
．． pp, Li2O2-Li2O2).

FIG. 2 shows the process after the ion implantation process is completed.

In a step after the ion implantation process, as shown in FIG. 2(a), a diffraction grating 9 is formed on the surface of the guide layer 7 corresponding to the location where the DBR region is to be formed. continue,
The cladding layer 10 and the cap layer 11 are grown as shown in FIG. ), the lower electrode 12-1,
Upper electrode 12-2 is formed. It also serves as heating during growth of the cladding layer 10 and cap layer 11 and heat treatment after ion implantation.

FIG. 3 shows a sectional view along the length direction of the mesa structure of the semiconductor optical device obtained by the above method, and FIG. 4 shows a sectional view taken along the line AB in FIG. 3.

This semiconductor optical device uses a non-disordered quantum well structure as a light emitting region 21, and a waveguide 22 in a waveguide region.
A phase adjustment region 23 and an OBR are formed in the refractive index control region.
A region 24 and a PM modulation region 25 are formed, and an AM modulation region 26 is formed in the absorption control region.

FIG. 5 is a diagram showing changes in energy bands due to disorder. In this figure, (a) shows the state before disorder, (b) and (C) show the state where disorder has progressed,
(6) indicates a completely disordered state.

As disordering progresses, the effective well width decreases, the first quantum level changes, and the bandgap increases.

The non-disordered region maintains the bandgap during crystal growth. Therefore, this area is designated as the light emitting area 21.
used as The oscillation wavelength of this light emitting region 21 is determined by its bandgap.

In the absorption control region, the band gap expands due to disordering, and the absorption edge correspondingly shifts to a slightly shorter wavelength side than the oscillation wavelength. Therefore, the absorption edge corresponding to the band gap is shifted to the shorter wavelength side than the oscillation wavelength of the light emitting region 21. Therefore, it becomes transparent in a steady state. However, when a current or voltage is applied to this region, the absorption edge shifts to the longer wavelength side and the absorption coefficient changes. By utilizing this change in absorption coefficient, this region can be used as the AM modulation region 26.

The refractive index control region has a higher dose than the absorption region, so
The degree of disorder is large. Therefore, the bandgap is larger than that in the absorption control region, and the change in absorption coefficient due to current or voltage is small. However, when a current or voltage is applied, the refractive index changes due to plasma effects, syntarch shifts, and other effects. Utilizing this refractive index change, this region is divided into the phase adjustment region 23 and the DBR region 24.
It can also be used as the PM modulation region 25.

The waveguide region becomes more disordered and the bandgap becomes larger. Therefore, the absorption edge shifts to the shorter wavelength side and the waveguide loss is reduced. Therefore, this region can be used as the waveguide 22.

The light emitting region 21, the phase adjustment region 23, the DBR region 24, and the surrounding structure form a variable wavelength Bragg reflection laser, the AM modulation region 26 and the surrounding structure form an AM modulator, and the PM modulation region 25 and the surrounding structure form an AM modulator. The surrounding structure forms a PM modulator. Regarding the operation of tunable Bragg reflection lasers, see, for example, Murata, Mido, Kobayashi, “Over 720 GHz (5,
8r++n) 7Requency Tuning Pi A1.5 Sir DBR Laser with Phase and Plug Wavelength Control φ Regions”, Electronics Letters Vol. 23 No. 8,
April 9, 1987 (S, Murata, I, Mi
to, K, Kobayashi, “0ver 72
0GHz (5,8nm) Frequency Tuni
ng by a 1.5μ[[1DBRLa5er
wxthPhase and Bragg Wavel
length Control Regions.

ELECTRONIC3LETTER3, Vol, 23
．． No. 8.9th April 119.87).

FIG. 6 shows the AL mixed crystal ratio of the quantum well structure of an actually manufactured semiconductor optical device.

In this example, GaAs is used as the active layer 5, and GRIN
AL, Ga+-x as layer 4.6 and guide layer 7
As is used. The width of the active layer 5 (quantum well width) Lz is 7.5 nm, and the width L0 of the 5 GRIN layer 4.6 is 150 nf.
l+, and the width Lg of the guide layer 7 is 50 nm. For this quantum well structure, using Si as the implanted ion species,
(1) Waveguide region implantation energy 100 KeV Dose amount S r = 1 xlQ12~l XIQls
cm-2 (2) Refractive index control region, absorption control region Implant energy 100 KeV Dose amount S2, S3 = 1 xlO" ~ 1 x1
Ion implantation was performed under the condition of 0.013 cm-2.

After this, the process shown in Figure 2 is performed, and the process shown in Figures 3 and 4 is performed.
We created a semiconductor optical device with the structure shown in the figure and confirmed that it actually operates. The temperature was raised at 770°C for 40 minutes in the second growth step (Figure 2B).

The measurement results of waveguide loss with respect to Si dose are shown in the table.

This table is Substrate 1: GaAs.

Buffed 77 layer 2an type GaAs, Cladding layer 3: n-type ALo, 5Gao, 4As.

GRIN layer 4: Undoped AL, Ga+-xAs.

GRIN layer 6, a disordered undoped quantum well layer
: Andove ALxGa+-xAs.

Guide layer 7: Undoped ALo, +Gao, Js
.

This is the result of measurement using a layer structure of cladding layer 10: p-type AL0.5Gao, 4^S, waveguide width: 6 μm, measurement wavelength: 845 nm. In this condition, S
The i dose amount is 1. By setting it to approximately OX10X10l3'', a waveguide with low loss can be obtained.

In the above embodiment, an example was shown in which the degree of disorder is controlled by the amount of ion implantation, but it can also be controlled by the type of ion implanted. For example, May, Vuencatesan, Siniwarz, Stoffel, Harbison, Hart, Floret,
"Comparative Studies of Ion Industrial Mixing of GaAs-A!As Subvarities", Applied Physics Letters Vol. 52, No. 18, pp. 1487-1479, 1988.5
March 2nd (PoMei, T, Venkatesan,
S, A, Schwarz, N, G, 5toffel,
Harbi-son, J.P., Harbi-son, D.L.
T, and L, A, Florez, ”
Comparative studies of 1on
-induced mixing of GaAs-
AlAs5upperlattices, Appl
, Phys, Lett, 52 (18), 2m
ay 1988. pp. 1487-1479), the degree of disorder can be controlled by the implanted ion species even under the same heat treatment conditions.

As an example of this, in the quantum well structure shown in FIG. 6, the quantum well width Lz = 7.5 nm, the width Lc of the GRIN layer 4.6 = 100 nm, and the width Lg of the guide layer 7.
=5Qn+n, and for this quantum well structure, (1
) Waveguide region implantation ion species Si Implantation energy 75 KeV Dose amount Sl = 1 x 1012 ~ 1 x 101 cm-2 (
2) Refractive index control region, absorption control region implantation ion species As implantation energy 400 eV dose amount 32, S3 = I ×1012 to 1 ×10
Ion implantation may be performed under the condition of "Cm-".

FIG. 7 to FIG. 1O show a DBR laser, a variable wavelength D
A method for manufacturing a BR laser, an ROR laser, and a variable wavelength ROR laser will be described. For ROR laser and variable wavelength ROR laser, Fig. 9(f) and Fig. 10(f) respectively.
A plan view is shown.

When manufacturing a DBR laser, a light emitting region and a DBR region are formed within the rib waveguide 20 in the same manner as the process shown in FIG. In this example, there are DBRs on both sides of the light emitting area.
Set up an area. A diffraction grating 9 is provided in the DBR region to disorder the quantum well layer in that region. In FIGS. 7 and 8, reference numeral 30 indicates the ion-implanted region. The upper electrode 12-2 is removed except for the light emitting region, and the remaining portion is used as the driving electrode 12-3.

In addition, in the case of a tunable wavelength DBR laser, the rib waveguide 2
A light emitting region, a phase adjustment region, and a DBR region are formed within 0. In each region, the upper electrode 122 is divided to form a driving electrode 12-3, a phase adjustment electrode 12-4, and a wavelength sweeping electrode 12-5.

The ROR laser has a structure in which a light emitting region 21 and a DBR region 24 are formed in separate waveguides, and a coupling region 40 is provided so that propagating light is coupled between these separate waveguides. D
BR regions 24 are provided on both sides of coupling region 40 .

To make the oscillation wavelength of the ROR laser variable, the light emitting region 2
A phase adjustment region 23 is provided in the waveguide on the first side, and a light emitting region 21
A drive electrode 12-3 is provided in the phase adjustment region 23, a phase adjustment electrode 12-4 is provided in the phase adjustment region 23, and a wavelength sweeping electrode 12-5 is provided in the DBR region 24 and the region therebetween.

Regarding ROR, see the paper by Kazarinov et al.
F Kazarinov, Charles H,
Henry and N, ^nders01sson
, ”Narrow-Bar+dResonant 0
Optical Reflectors and R
e5onant Transformers for
La5er Stabilization and
Wavelength Division Mult+
plexing”, IEEE J, mouth uantum
Electron, VOI, QB-23°No. 9
．． September 1987).

Regarding semiconductor lasers using ROR as an external cavity, see the paper by Olson et al.
.

C, H, Henry, R, F, Kazarinov,
H., J. Lee, B. H. Johnson and
K. J. Orlowsky, “Narrow li.
newth l, 5μ[[lsemiconduct
tor 1aser with a reso
nanoptical reflector, A
ppl, Phys, Lett, 51(15).

12 Oct., 1987). Furthermore, the present applicant has already filed a patent application for a technology for integrating a semiconductor laser and an ROR on the same substrate (Japanese Patent Application No. 63-218981).

Although 28S1 was used as the ion to be implanted in the above embodiment, the present invention can be implemented in the same manner using other ions.

Further, regarding the structure of the semiconductor laser, other structures such as a light confinement structure may be used as long as it uses a quantum well structure. Therefore, the present invention can be similarly implemented even when manufacturing broad area semiconductor lasers or laser arrays.

[Effects of the Invention] As explained above, since the semiconductor optical device of the present invention controls the band gap by the degree of disorder of the quantum well structure, various types can be grown on the same substrate without complicating the crystal growth process. This has the effect of integrating optical devices with a band gap of . Furthermore, since the waveguide structure is the same in all regions, there is an effect of increasing the coupling efficiency between optical elements.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a method of manufacturing a semiconductor optical device according to an embodiment of the present invention. FIG. 2 is a diagram showing the process after ion implantation. FIG. 3 is a sectional view of the embodiment. FIG. 4 is a sectional view of the embodiment. FIG. 5 is a diagram showing changes in energy bands due to disorder. FIG. 6 is a diagram showing the band structure of a quantum well structure. FIG. 7 is a diagram showing a method of manufacturing a DBR laser according to a second embodiment of the present invention. FIG. 8 is a diagram showing a method of manufacturing a tunable wavelength DBR laser according to a third embodiment of the present invention. FIG. 9 is a diagram showing a method of manufacturing an ROR laser according to a fourth embodiment of the present invention. FIG. 10 is a diagram showing a method of manufacturing a tunable wavelength ROR laser according to a fifth embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Buffer layer, 3.10... Clad layer, 4.6... GRIN layer, 5... Active layer,
7... Guide layer, 8... Mask, 9... Diffraction grating, 11... Cap layer, 12-1... Lower electrode, 1
2-2... Upper electrode, 12-3... Drive electrode, 1
2-4... Electrode for phase adjustment, 12-- Electrode for wavelength sweeping, 20... Rib waveguide, 21... Light emitting region, 2
2... Waveguide, 23... Phase adjustment region, 24...
DBR area, 25...PM modulation area, 26...AM
Modulation region, 30... Ion-implanted region, 40...
- Combined area. Patent Applicant Optical Measurement Technology Development Co., Ltd. Agent Patent Attorney Nao Takashi Ide 8” Hotoriko Umajima (Q) (C) 5 times of swearing X = Tori 6 Figure

Claims (1)

[Claims] 1. A semiconductor comprising, on the same substrate, a light-emitting region formed by a quantum well structure and a waveguide region through which light emitted from the light-emitting region is guided and whose band gap differs from that of the light-emitting region. 1. A semiconductor optical device, wherein the waveguide region includes a disordered region in an extension of the quantum well structure. 2. A method for manufacturing a semiconductor optical device in which a quantum well structure is formed on a substrate and at least a part of the quantum well structure is disordered, in which the bandgap of the region is made variable by controlling the degree of disordering. 1. A method of manufacturing a semiconductor optical device, comprising: setting. 3. The method of manufacturing a semiconductor optical device according to claim 2, wherein the disordering is performed by ion implantation and heat treatment, and the degree of disordering is controlled by controlling at least one of the dose amount and the implantation energy in the ion implantation. 4. The method of manufacturing a semiconductor optical device according to claim 2, wherein the disordering is performed by ion implantation and heat treatment, and the degree of disordering is controlled by selecting the type of ions to be implanted in the ion implantation. 5. a first growth step of growing a semiconductor layer including a quantum well structure on the substrate; a second growth step of growing another semiconductor layer on this semiconductor layer to form a semiconductor laser structure; 5. The method of manufacturing a semiconductor optical device according to claim 3, further comprising performing ion implantation following the first growth step, and performing the second growth step after the ion implantation is completed. 6. The method of manufacturing a semiconductor optical device according to claim 5, wherein the heat treatment is performed simultaneously with the formation of the semiconductor layer by increasing the temperature in the second growth step. 7. The method of manufacturing a semiconductor optical device according to claim 5 or 6, wherein a Bragg reflection region is formed in a region where the quantum well structure is disordered. 8. The method of manufacturing a semiconductor optical device according to claim 5 or 6, wherein a variable wavelength Bragg reflection region is formed in a region where the quantum well structure is disordered. 9. The method for manufacturing a semiconductor optical device according to claim 5 or 6, wherein a resonant optical reflector is formed in a region where the quantum well structure is disordered. 10. The method for manufacturing a semiconductor optical device according to claim 5 or 6, wherein a tunable wavelength resonant optical reflector is formed in a region where the quantum well structure is disordered.