JPS5951584A - Semiconductor laser - Google Patents

Abstract

PURPOSE:To take a stable oscillation attitude in cooperation with a gain waveguide mechanism by stripe structure by forming substantially fixed refractive index difference regarding the lateral direction. CONSTITUTION:The epitaxial growth of first-fifth semiconductor layers 11-15 can be formed by continuous work through a vapor growth method by a thermal decomposition method using substances, such as trimethyl aluminum, trimethyl potassium and arsine as reaction gases or a liquid growth method or other growth methods-that is, by once epitaxial growth treatment. Consequently, the fourth semiconductor layer 14 is constituted. The forbidden band width of Ga1-yAlyAs is selected so that it is made larger than that of the active layer 12 in the manner not to absorb beams generated from the active layer 12 in the value of (y) of Ga1-yAlyAs, which is the quantity of Al.

Description

[Detailed description of the invention] Industry - Utilization of The present invention relates to semiconductor radar.

BACKGROUND TECHNOLOGY AND PROBLEMS In semiconductor lasers, various stripe structures are used to concentrate the C operating current in order to generate a continuous beam of light with high density optical signals. There are some devices in which the width of the effective oscillation region in the active layer is narrowed. Examples of "C1" include the so-called electrode stripe type in which the electrode contact part is striped, 1. Pre-nurse 1-live type, and Prol.
For example, the stripe type caused by irradiation with irradiation can be mentioned. In the lateral direction, the oscillation state is determined by -1°C due to the stimulated emission gain generated by the injected carriers.
Regarding the transverse direction, the carrier and the light are not confined.

On the other hand, "ζ" is a cell in which a semiconductor layer is selectively provided to form a difference in refractive index in the lateral direction to define a light emitting region in the layer.
-Ser was proposed in Japanese Patent Application Laid-Open No. 55-408790 (1987).This semiconductor laser is based on the N-type lnP base treatment (1), as shown in Fig. 1. A first clan of N-type TnP F' r@+21 is epitaxially grown, followed by ten of this I n Ga A s
An active layer of P is epitaxially grown, and then a second crat layer (4) of P-type InP is epitaxially grown, and on top of this a second crat layer (4) of P-type InP is grown epitaxially.
A high refractive index layer (5) of aAsP is grown epitaxially. These M(1) to (5) are performed in one continuous epitaxial growth process, but next, the epitaxial growth is stopped and the layer (5) with a small forbidden band width and high refractive index is formed. A mask layer made of, for example, 5i02 is selectively formed on the surface, and using this as an etching mask, the high refractive index layer (5) is removed by etching to a required width W. After that, the above-mentioned Sio2 mask is removed, and the cladding layer (4
) and forming a similar cladding 1M.
A layer of P (6), and on top of this a layer of ■ for ohmic contact.
A 21st l-II 1=:l corbitaxial growth process is performed in which the I layer (7) is sequentially grown on the )-type InGa 8sP. Electrodes (8) and (9) are ohmically applied to the ohmic contact layer (7) and the roots (1), respectively.

In a semiconductor radar with such a configuration, the current confinement is performed at ' by the d]1 refractive index layer buried in the cladding layer, and the light generated in the active IPf t31 is absorbed here, so that the effective This is to create a refractive index difference in order to improve the function of the waveguide mechanism based on the refractive JJi index difference (this is to stably control the oscillation mode in the transverse force direction).

However, since a semiconductor laser with such a configuration has a high refractive index layer of 1 m embedded in the cladding layer, it is impossible to manufacture a fake by a series of epitaxial growth processes, and as mentioned above, In addition, it becomes necessary to divide the process into two J-bitaxial growth processes, making the manufacturing process complicated. Furthermore, there is a great risk that the surface of the conductor layer will be oxidized or stained with Ifi due to the difference between the first epitaxial growth treatment and the second epitaxial growth treatment and the second epitaxial growth treatment. The occurrence of defective products is 101 times more likely.

As described above, the present invention is equipped with a wave machine (h), so to speak, and stable control of the attitude of the wave in the direction of the bucket. The purpose of the present invention is to provide a semiconductor laser which avoids the above-mentioned drawbacks by employing a structure in which the semiconductor laser is manufactured using a single continuous epitaxial growth process.

SUMMARY OF THE INVENTION The present invention provides a first semiconductor layer, a second semiconductor layer, a third semiconductor layer, and a fourth semiconductor IP layer that are sequentially adjacent to each other.
i, a first portion of the same conductivity type as the third semiconductor layer, and a second portion of the opposite conductivity type are provided in at least the fourth semiconductor layer; The distance between the part and the semiconductor layer 9f~2 is such that the light emitted from the second semiconductor layer is
The forbidden band width of the second semiconductor layer is smaller than that of the first and third semiconductor layers, and the forbidden band width of the first part is 2(7);l'. It is more human than that of the conductor layer,
The second part! 4.1t:'! ti11'it1 is the second
The same or smaller than that of 214 conductor layers.

Embodiments The present invention can be applied to a substrate of the first conductivity type 0]1), for example, a l) type (: a A s group () as shown in FIG.
lv], and on top of this, a Hanofub layer and first semiconductor layer of the same conductivity type, for example, P-type Ga, 48 I□A s.
Ifi (11) was epitaxially grown 14, and in history, ten cases of /L of the same /# conductivity type or a different conductivity type were formed.
+, gender) -1 second semiconductor layer, for example ■) type G
a1-xA to IX8 IM (12) is epitaxially deposited, and a third semiconductor layer, for example, N-type Ga, -2, is formed on J- to become the second clan 1 layer of the second conductivity type.
^128S layer (13): L bitaxially grown, and further on top of this, a fourth semiconductor layer as a control layer of the same m type, e.g., N type Ga1. -y^
1yAs1 (14) was epitaxially grown, and the fifth semiconductor layer, for example N-type surface concentration, had the same conductivity type as the θ-contamination and was used for ohmic deposition of the electrode. A second GaAs layer (15) is grown bitaxially. To the first and fifth semiconductor layers (11) to (15)
) can be grown using the vapor phase growth method using trimethylaluminum, 1-limethylgallium, or arsine as the reaction residue, or the slaked growth method, or other growth methods. Through continuous work,
ZnI can be formed by one more epitaxial growth process.

, secondly, Ga constituting the fourth semiconductor + fi (14)
1-, 1 to y. The amount of y of 8S (direct, that is, the amount of 8I is
The forbidden band width of the active layer (12) is selected to be larger than that of the active layer (12) so as not to absorb light emitted from the active layer (12).

In particular, in the present invention, the fifth semiconductor layer (15
) From above, Zn as an impurity of the first conductivity type, for example, P type, is selectively introduced by the expansion method, ion implantation method, etc. to form a striped portion extending in a direction perpendicular to the color of the paper in FIG. The second conductivity type is left as the first part (16) of the second conductivity type, and the second conductivity type is canceled on the Fiq side of the second conductivity type, thereby forming a second part (+7) that eliminates the first conductivity type. The depth If of this second portion (17) is the depth near the boundary fh1 between the fourth shore conductor layer (14) and the third semiconductor layer (13), as shown in Fig. 2. As shown by the broken line al in FIG. Everything I do is C-cut, but? b) 2's'1yt-
(Book (bait, 1) 71'!'i l+'i t!l I
This second part (17) without reaching n(12)
and the second semiconductor layer (12) or this activation activity [4
The depth at which the light oscillated from (12) reaches region (16) is, for example, a distance approximately equal to the wavelength of this region.

In addition, as mentioned above, the second semiconductor layer (12)
Prohibited zone 'l'! d is the first and 30th conductor layer (
11) and that of (] + 3, having L smaller ff, 1., these first and f: (S 3 half-body j director (
11) and (13) and the second semiconductor layer (12) form a groove, and the first and NS3 semiconductor layers (11) and (13) form the second semiconductor layer (12). Layer (1
2) The layer 1 does not have the ability to function as a ``claso layer overlying the active layer 15''.

Then, in the second portion (17) where an impurity, for example Zn, is selectively introduced into at least the fourth semiconductor layer (14), 7. n4W person-2 and its prohibition 1
1- Narrow the bandwidth so that light from the active IN (12) is absorbed. This Zn introduction h1 was described in I-. 1
, the N-type of the sea urchin semiconductor layer (14) is checked from 11° (I)
It may be a rhinoceros that is inverted to jjv. In this case, it is preferable that the V conductor X in the Zn introduction part be an N-type conductor with a +[1f concentration. This is because the N type 1f''llJll degree works in the direction of widening the forbidden band width, and when Zn is introduced to reverse this conductivity type, it becomes more prohibited (:!++'ii
1 in the direction of narrowing (depending on each).

For example, the semiconductor layer (+5), J- is an insulating layer (18).
is deposited and an electrode aperture is formed thereon, and one 1! is formed on the part having the first part (16). pole (1
τ)) is ohmically connected and deposited, and the other Yi pole (20) is ohmically connected and deposited on the back surface of the substrate tlO).

According to the J double semiconductor radar, the striped first
The presence of second parts (17) of a different conductivity type on both sides of the part (16) reduces the effect of current flow, has a gain waveguide type mechanism, and ; (
The light oscillated at Il 1m (12) is transmitted to this part (17
), due to the absorption effect of 1, the active layer (12)
ζ with respect to the lateral direction of substantially the second part (17) ``'
A built-in refractive index difference is formed in the portion corresponding to F, and the result is i!1゛ζ, which also functions as a refractive index difference waveguide mechanism in the lateral horn direction.

In the example shown in Figure 2, the artificial angle IJi 't<4
In the case where the second portion (I7) that causes the difference is formed by selectively introducing impurities by diffusion, etc., the first 111th part (16 ) can also be formed.An example of this case is shown in Fig. 3.In Fig. 3, the part corresponding to 2nd and 1 is given the same code as E1 and written as JJ-. Although the explanation will be omitted, in this example, ζ is the fourth and fifth semiconductor layers (14) and (15) of the first conductivity type, CIJS4 length, and a striped N-type impurity of the second conductivity type. is selectively expanded 11 and introduced by a method or the like to a depth that does not reach the t,!i layer (12) to form the first part (16), and the saw part where this introduction is not performed. to the second part (1
7). In this case, the second part (17) 1. Therefore, at least during evictential growth, the composition of this 4' IN (14) should be such that it functions as the second part described in 11-2 and has a composition that increases by +2. ζ is assumed to be 1-, which has almost no light absorption effect, as described above.

Effects of the Invention As described above, according to the configuration of the present invention, by forming a substantially built-in refractive index difference in the lateral direction, the gain waveguide mechanism using the stripe structure works well with the structure of the present invention. It is possible to do this without taking a stable oscillation state.

In particular, in the present invention, as a light absorption layer that forms this built-in refractive index difference, the second part of °C is not made into a buried structure but is formed by selectively introducing impurities from the surface. Alternatively, since it is formed by a region regulated by this region, each 4',','; 1 body layer (11) to (1
5) is formed in a series of epitaxial growth processes, that is, in one epitaxial growth process, and no operations are inserted in the middle of the process. Therefore, manufacturing operations are streamlined and 4L productivity is improved, and at the same time, in compound semiconductors containing 8L, which is easily oxidized, the surface of this semiconductor layer is However, the structure of the present invention does not have such disadvantages, so it is possible to outperform semiconductor lasers with excellent characteristics. It is possible.

In addition, particularly in the present invention, each impurity-introduced region forming the second portion (17) as the light absorption layer or the first portion (16) for current concentration is shown in FIG. (as shown in Figure 3), the active layer (12) is selected at a depth that does not reach the active layer (12), so crystallographic distortions or defects that accompany the introduction of this layer may affect the oscillation region. If this is the case, it is possible to avoid the occurrence of -4, and it is possible to perform an IF of a semiconductor laser that has excellent characteristics and is stable.

[Brief explanation of drawings]

FIG. 1 is an enlarged line 1v [plane view] of a conventional semiconductor laser, and FIGS. 2 and 3 are enlarged line 1tJi plane views of an example of the semiconductor laser according to the present invention. 00) is the semiconductor substrate, (11) to 115) are the first to fifth
, (16) and (17) are the first and second semiconductor layers.

Claims (1)

[Claims] a first semiconductor layer and a second semiconductor layer that are sequentially adjacent to each other;
a third semiconductor J- and a fourth semiconductor 1-;
At least a first portion of the same conductivity type as the third semiconductor layer and a second portion of the opposite conductivity type are provided in the fourth semiconductor layer, and the second portion and the second portion are provided in the fourth semiconductor layer. The distance to the semiconductor layer is such that light oscillated from the second semiconductor layer reaches the second portion, and the forbidden band width of the second semiconductor layer is the distance between the first and third semiconductor layers. The forbidden band 1υ1 of the first part is smaller than the forbidden band width of the second semiconductor layer, and the forbidden band 1υ1 of the second part is smaller than the forbidden band width of the second semiconductor layer.
Is the band 11'i4 the same as or smaller than the forbidden band width of the second semiconductor rf4? 1 conductor laser.