JPS58197788A - Manufacture of distribution feedback type semiconductor laser - Google Patents

Abstract

PURPOSE:To obtain a distribution feedback type laser with oscillating wave length at designed value subject to favorable yield by a method wherein, after GaInAsP active layer and a guide layer is preliminarily grown, a cyclic structure as a double hetero structure is formed on GaInAsP layer. CONSTITUTION:An N type InP layer 12, no additive layer 13, P type GaInAsP guide layer 14 are liquid epitaxially grown on (001) surface of N type Inp substrate 11. A resist film is interference exposed by means of He-Cd layer and developed to form a mask further etching a layer 14 to form a cyclic structure 15 (period 4,700Angstrom ) with stripes in parallel with the direction of (-110). Next N type InP layer 16 and P type GaInAsP layer 17 are laminated and a current narrowing structure is introduced to complete a distribution feedback type laser. In such a constitution, the cyclic structure provided on GaInAsP layer 14 with less P component resistant to dissociation of P i.e. thermal deteroration will not be destroyed even if the layer 16 is grown at 590-520 deg.C favorably controlling oscillating wave length to obtain the oscillating wave length at designed value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing a Ga1nAsP/summer nP distribution fI# quantity-shaped biosemiconductor radar device used in optical communications.

[Technical background of the invention]

Using ImpP as a substrate 90a I IIAIP/I
The nP double-hetero structure semiconductor radar device has a wavelength of 1.
It is attracting attention as a light source for round and nine-fine communications with an oscillation wavelength of ~16μ. Among them, distributed feedback type semiconductor radar devices using a periodic structure (diffraction grating) are suitable for next-generation O1m level communication because they can obtain single-wavelength operation not only during DC operation but also during transition. It is in the spotlight as a light source. On the other hand, in order to enable long-distance transmission in the 1.5μ wavelength range, which is the extremely low loss region of silica-based optical fibers, the advent of semiconductor radar equipment that can obtain single wavelength oscillation is required. desired.

and Corote, recently, Ga111 with a wavelength of 1.5 A11ll.
The continuous oscillation power at room temperature of mP/InP distributed feedback type semiconductor radar devices has been reported. Such a semiconductor laser device is manufactured by the following method. First, Figure 1 (&
), m-type 1 mF substrate J (D surface V periodic structure 2
Process. Next, by one liquid phase formation cycle of the periodic structure JIIK of the substrate J, a guide layer 1 of υn type Gal+am sP, an active layer 4 of Ga1am mP, a Khu, do layer 5 of p type 1 mP, and a p type GaI film are formed. MmP's cat! The layers C are successively grown (as shown in FIG. 1(b)), and the thus formed double heterostructure wafer achieves laser oscillation by employing a current confinement mechanism such as a conventional buried structure. The guide layer 3 has a larger punt gear, f, than the active layer 4, so that light propagates through the active layer 4 and the guide layer JKI. On the other hand, the injected carriers are confined in the active layer 4 ~ so-called S@pa
rat@Confin@m@ntH@t@restru
The @tur* (8CH) structure is employed. As mentioned above, the periodic structure for distributed feedback that enables single wavelength operation is processed into the n-type InP substrate 1. The reason why a substrate with a periodic structure processed in this way can be used is that Ga1nAsP
/In IaP-based semiconductor radar devices, the InP substrate has a different wavelength than the oscillation wavelength.

This is because IMP is transparent and has a smaller refractive index than GaInAsP. Therefore, it is now possible to fabricate a double heterostructure wafer using just one liquid phase epitaxial growth cycle as described above.

[Problems with background technology]

However, the above conventional manufacturing method has the following problems in liquid phase epitaxial growth C) 8th floor.The first problem is that the periodic structure processed on the InP substrate is completely or almost completely removed during the liquid phase epitaxial growth stage. It is to disappear. The period of the complementary structure differs depending on the order of diffraction, but when using the highly efficient first order, it is 240 ntng degrees for an oscillation wavelength of 1.5 m. Also, its depth is at most 100 arms. Such a minute periodic structure is formed during the dissolution of the seed crystal in the growth solution during liquid phase epitaxial growth, or during the formation of the first layer of GaImA.
It disappears during the growth of the aP guide layer 3.

This is thought to be due to thermal deterioration of the InP substrate caused by the high vapor pressure of P at the nucleus growth temperature during crystal growth. For this reason, the production yield of semiconductor radar devices using the conventional method is extremely poor.

W, 20 The problem is the controllability of the oscillation wavelength.

Generally, if the period of the periodic structure is A, and the refractive index determined from the layer thickness and refractive index of the GaInAsP guide layer 3 and active layer 4 is "off," then the oscillation wavelength λ of the distributed feedback type is λ- It is given by 2J m, 11/m' (m: -order of folding: 1, 2.3...).The period of the periodic structure depends on the positional accuracy of the interference optical system using laser light, It is possible to manufacture it with relatively high precision.On the other hand, it is difficult to obtain a value of 9 according to the design for the equirefractive index OFF.

This is because the thickness of the epitaxial layer varies due to liquid phase epitaxial growth.

For this reason, add a periodic structure to the substrate in advance.
With conventional structures, it was difficult to maintain the oscillation wavelength as designed.

[Purpose of the invention]

The present invention is directed to providing a method for manufacturing a minute feedback type semiconductor radar device that sets an oscillation wavelength as a designed value with a high production weight.

[Summary of the invention]

In the present invention, after growing a GaInAaP active layer and a guide layer in advance, a periodic structure is formed in a GaInAaP quaternary layer that is resistant to thermal deterioration, and a double heterostructure is obtained. The key point is to manufacture the feedback type semiconductor radar device in Keigari.

[Embodiments of the invention]

Next, embodiments of the present invention will be described with reference to FIGS. 2(e) to 2(e).

First, using a normal liquid phase epitaxial growth apparatus IT equipped with a carn-made structure, a (001) 0.2 μm thick 1 m IP/42 F layer 12 and a 0.2 μm thick non-doped layer 12 are grown on a (001) 0.2 μm thick InP substrate IJ. Ga1mAsP active layer 11 and thickness 0.2 sm Op type Ga1mAsP
The guide layer 14t is continuously epitaxially grown.
C (as shown in Figure 2(a)), each layer is, zs, i at this time
The growth start temperature of 4 is 610℃, 592C15917 respectively.
The temperature drop was set at 0.6°C/min. The photoluminescence wavelengths of the grown r-occupied layer 13 and light guide layer 4 were 1.5 Jl and 1.2 tones, respectively, and were similar.

Next, the surface of the Ga1aAsP light guide layer 140 was spinner coated with Renost, and further coated with 44% of H.-Cd Rede.
In step 16, the resist film is exposed to light by an interference exposure method using light, and a resist/mother turn (not shown) is formed by a photolithography process. Using the resist 9 turns as a mask, the surface of the light guide layer 14 is coated with bromine. A striped periodic structure J5 with a period of 47001 parallel to the (10) direction was formed by selective etching with a mixture of water and phosphoric acid (Fig. 2(b)).
Next, after performing a normal cleaning treatment, the optical guide layer 140 periodic structure 1 is grown using a similar liquid phase epitaxial growth apparatus.
5 is formed with a p-type ImpP layer 16 and a p-type ImpP layer 16 and p
A double heterostructure sea urchin was fabricated by continuously growing the vGjInAaP cap layer it (Fig. 2 (,)
(Illustrated). Thereafter, a distributed feedback type semiconductor Lede family f (not shown) was manufactured by introducing a current confinement mechanism such as a conventional stripe electrode structure or a buried structure into the wafer.

Therefore, according to the method of the present invention described above, GaI which has a low P (phosphorus) component and less dissociation of P, that is, is resistant to thermal deterioration.
Since the mAaP optical guide layer 1 optical pressure 41 layer 145 is formed and the p-type InP layer IIi is liquid-phase epitaxially grown thereon, it is possible to prevent the periodic structure 15 from disappearing due to thermal deterioration.

In fact, the growth starting temperature of #1IP layer #P layer is set to 5e.
The periodic structure 15 on the surface of the light guide layer 14 was preserved even when the temperature was changed in the range of oc to 520°C.

Further, eradication of the periodic structure 15 can be more reliably prevented. That is, in the first stage of the second liquid phase epitaxial growth, the InP clad layer 16 is grown, so compared to the conventional method in which type 1 QaI ROM sP and f oid layers are grown on the periodic structure. This makes it possible to grow at low temperatures.

Since the vapor pressure of P (phosphorus) changes exponentially with temperature, the fact that the growth temperature can be lowered from the conventional 600-odd degrees to 56-odd degrees, 100 degrees Celsius lower, is due to the amount of P vapor. can be considerably reduced, and thermal deterioration can be further suppressed. Moreover, in the conventional case, when a Galn-P active layer is grown on an InP substrate at a low temperature, the solubility of P in the In solvent decreases, resulting in an extremely low saturation amount of P in the active layer. However, in the case of the present invention,! ! In order to grow IP, growth in the aforementioned low temperature region is fully possible. Also, G
When depositing InPn on the aImP light guide layer 14, the Ga1nAsP light guide layer 14 due to non-equilibrium of the solid-liquid phase.
It has the advantage of solving the problem of dissolution.

Furthermore, in the method of the present invention, the GaInAsP active layer 13 and the G
After forming the a1mAsP optical guide layer 14 and knowing the epitaxial growth film thickness thereof, it is possible to process the periodic structure 15 on the surface of the optical guide layer 14. In other words, after knowing the equivalent refractive index "vff" of the optical waveguide structure consisting of the active layer 13 and the light id layer 14, the periodic structure 150 to be formed is
Since it is only necessary to determine the entire period, the controllability of the oscillation wavelength is good, and a semiconductor single crystal device having the oscillation wavelength as designed can be obtained.

In the above embodiments, the periodic structure was formed using a wet method using a mixed solution of bromine, water, and phosphoric acid, but the periodic structure may also be formed using a dryer method or a Dender method.

〔Effect of the invention〕

As clearly stated above, according to the present invention, it is possible to prevent the periodic structure from disappearing during epitaxial growth, and the oscillation wavelength can be well controlled, so that the oscillation wavelength matches the installation V value suitable for optical fibers and optical sources. This method has remarkable effects such as being able to manufacture distributed feedback semiconductor laser devices with high yield.

[Brief explanation of the drawing]

FIGS. 1(1) and 1(b) are cross-sectional views showing the manufacturing process of a distributed feedback semiconductor radar device using a conventional method.
! FIGS. 2(a) to 2(e) are cross-sectional views showing the manufacturing process of a distributed feedback semiconductor radar device in an embodiment of the present invention. 11-n type 1rsP JGi plate, 2-n type ImpP plate,
F layer, 13...Nondo;/'Ga1nAsP active layer, 14...p-type GaInAiP light guide layer, J5
...periodic structure, 1i-p type 1mP clad layer, do layer, 17
=-p 槃hInAsPkya,! layer. Applicant's agent Patent attorney Takehiko Suzue 15CI Figure 2

Claims (1)

[Claims] In manufacturing a semiconductor radar device made of Ga1nAsP/NatsunP, Gax'Int-x'Asy'P1-y'
(However, GaxIml-xAsyPl-y, which has a larger bandgap than the active layer on the surface of the active layer consisting of O(x' (1*0 <y'< 1) (however, 0(x(1,0 A method for manufacturing a distributed feedback semiconductor radar device, comprising forming a guide layer consisting of y (indicating 1), further processing a periodic structure on the surface of the guide layer, and then forming a double heterostructure.