JPS5944887A - Semiconductor light emitting device - Google Patents

Abstract

PURPOSE:To improve integration density by blocking reactive current by using a semi-insulation semiconductor layer as the semiconductor layer which decides the division of a current passage to the light emitting region. CONSTITUTION:The semi-insulation InP layer 12 doped with chrome by vapor growing method is grown on an N type InP substrate 11. Using the mask, a groove 20 in stripe form of the width of approx. 3mum is mixture-formed to the depth enough for reaching the substrate 11 by penetrating the layer 12. The first N type InP clad layer 13, a non-doped InGaAsP active layer 14, a second P type InP clad layer 15 and a P type InGaAsP cap layer 16 are successively grown by LPE method to the thickness whereby the upper surfaces thereof become nearly the same plane as the upper surface of the layer 12. Then, the stripe region is sandwiched only between the layers 12, resulting in current stricture, and therefore the problem of the dispersion of the relative positional relation between the semiconductor layer of the stripe region and that of the current block region is not generated.

Description

[Detailed Description of the Invention] (a) Technical Field of the Invention The present invention relates to the structure of a semiconductor light emitting device, in particular, the dark value current is reduced, the reactive current is blocked, the dispersion of characteristics is reduced, and the reworkability is improved. This invention relates to the structure of a semiconductor light emitting device.

(b) Conventional technology and four-point combination In optical fiber communications and other industrial and consumer fields where light is used as the medium of information No. 4N, semiconductor light emitting devices that generate optical signals fulfill the most important functions and their characteristics. There is a strong demand for stability and reliability.

Although many proposals have already been made regarding the structure of semiconductor light emitting devices, a conventional example of a buried structure semiconductor laser in which an active layer etc. is formed in a groove provided in a semiconductor layer is shown in FIGS. 1(a) and 1(a). This will be explained with reference to the cross-sectional view shown in (b).

As shown in Figure 1(a), n-type indium phosphorus (InP)
) A p-type InP layer 2 is formed on a substrate 1 by a method such as liquid phase epitaxial growth (hereinafter abbreviated as LPE).A mask 3 is formed by a silicon dioxide (5i02) film provided in contact with the pfflInP layer 2. ″f：
Formed and selectively etched to form an n-type InP group &1
A striped groove 4 is provided with a depth reaching .

Next, as shown in FIG. 1(b), after removing the mask 3'lt, an n-type InP first cladding layer 5 is formed by LPE.
, non-dorg indium Φ gallium arsenide-g (I
nGaAsP) active layer 6, p-type InP second cladding rV
J7 and a p-type InGaAaP cap layer 8 are formed 11 times later. At this time, an n-type InP layer 5' and a non-doped InGaAsP layer 6' are formed on the p-type 1nP layer 2 outside the trench 4.
grows. Next, after adjusting the thickness of the n-type InP substrate 1, a p-side electrode 9, an n-side electrode 9, and a pole 1o are provided.
The forbidden band width of the first cladding layer 5 and the p-type InP second cladding N7 is p larger than that of the InGaAsP active layer 6, and carriers are confined in the InGaAsP active layer 6. The active As layer is small and light is also confined in the active layer 6.

In addition, the %H flow flowing with the p-side electrode 9 as positive and the 11-side electrode 10 as negative is between n-type InP counterfeit 5' and p-type InP.
The path outside the stripe region is blocked by the n-p junction interface formed by the InGaAsP layer 2. However, in the previous Me conventional structure, when the current density is increased, the current does not pass through the InGaAsP active layer 6. In addition, a reactive current that does not contribute to laser oscillation is generated along the current path from the p-type InP second cladding layer 7 to the p-type InP layer 2 to the n-type InP substrate 1.

Moreover, this reactive current flows between the InGaAsP active layer 6 and the n
It changes depending on the relative positional relationship with the -p junction interface, and is one of the causes of variations in the characteristics of semiconductor lasers with this structure.

Factors contributing to this variation in characteristics include the diffusion of impurities at the semiconductor region interface during the formation of the epitaxial growth layer, for example at the exposed surface of the trench 4, and in the vicinity.

It is extremely difficult to suppress the above-mentioned variations in characteristics by improving control during LPE growth, and suppression of reactive current is necessary not only to improve quantum efficiency but also to improve reliability. For certain reasons, there is a demand for a proposal for a 44JJ semiconductor laser that solves the above-mentioned problems.

(c) Purpose of the Invention The present invention aims to provide a semiconductor light emitting device in which reactive current is prevented and dispersion of characteristics due to the relative positional relationship of the active layer and other semiconductor layers is suppressed. .

(d) Structure of the Invention The object of the present invention is to provide a semiconductor light emitting device using a semi-insulating semiconductor layer as a semiconductor layer defining a receptacle and a flow path to a light emitting region.

In particular, a semiconductor light emitting device in which a semiconductor layer constituting the entire photoelectric conversion section and a side end portion of the semiconductor layer provided between the semiconductor layer and the negative electrode are terminated by contacting a semi-insulating semiconductor layer. In conventional semiconductor light emitting devices, the side edges of the active layer and the like are terminated with a conductive semiconductor layer, and current confinement is achieved using a pn junction and a difference in built-in potential, whereas this g6QLJ In semiconductor light emitting devices, current confinement is achieved using a semi-insulating semiconductor layer that is lattice-matched to the substrate, especially a semi-insulating semiconductor layer that has a lower refractive index than the active layer, thereby improving its characteristics and simplifying its structure. f: To be achieved.

(e) Embodiments of the Invention The present invention will be specifically described below by way of embodiments with reference to the drawings.

FIG. 2 is a perspective view showing an example of implementing the present invention for a semiconductor laser, in which 11 is an n-type InP substrate, 12 is a semi-insulating InP layer, fi5.13 is an n-type InP first cladding layer,
14 is a non-doped InGaAsP active layer, 15 is a p-type 1np second cladding layer, 16 is a p-type In-GaAsP cap layer, and 17 is a p-side '? I, pole, 18id:nI0
Shows electrodes.

An outline of the method for manufacturing the semiconductor laser of the above embodiment will be explained with reference to FIGS. 3(a) and 3(b).

As shown in FIG. 3(a), IC semi-insulating InP 7m 12 is grown on an n-type InP substrate 11 to a thickness of about 4 μm, for example, doped with chromium ('Cr)'e by vapor deposition method. . Mask 19'f consisting of 5in2: using 1
For example, hydrochloric acid (H(u) and nitric acid (HNO
As shown in (b), the front M'L mask 19 is formed by etching using a mixed solution with s).
n-type InP first cladding/I+1 without removing
3 total 7! Size 2 [About 8m70, non-doped InGa
The AsP active layer 14 has a thickness of about 0.2 C, ttrn,), and the p-type InP second cladding layer 15Q has a thickness of about 2 (about 2), so that the upper surface of the uInGaAsPInGaAsP layer is on the order of 0.2C, ttrn, ). The layers are sequentially grown by LPE to a thickness that is substantially flush with the upper surface. This L
In PE growth, the surface outside the trench 20 is covered with a mask 19 of 5i02, which is different from the conventional example, so no semiconductor layer is deposited in this region.

Next, the mask 19 is removed using SiOx, the thickness of the n-type InP substrate 11 is adjusted, the p-side electrode 17, the ri side ↑↓3, and the pole 18 are formed, and the edges of the end face I5i'1, etc.'
tr: By carrying out 111J steps, the semiconductor laser quantum shown in No. 21-1 is completed.

Note that if the p-side electrode is formed without removing the mask 19 of 5i02, this 5i02j friend is 11
Promotes the effect of flow stenosis.

In the semiconductor laser of the present embodiment described above, the stripe region is narrowed only by the semi-insulating semiconductor layer to effect current confinement, and the semi-insulating semiconductor layer also has the effect of refractive index guide. Unlike the conventional example, the problem of variation in the relative phase relationship between the semiconductor layer in the stripe region and the semiconductor layer in the current (!old [1- region)] does not occur.

As a result of measuring the characteristics of this actual ornament, the Kl value current was approximately 10 [rnA], no reactive current was detected, the quantum efficiency was approximately 30 [chi] per surface, and the dispersion of the characteristics was also Significant improvements are being achieved.

Although the embodiment described above is a single semiconductor laser, the semi-insulating semiconductor layer, which is a feature of the present invention, also has the effect of isolating elements, and is highly densely formed in Hayabusa's circuitry including light emitting elements. This makes it easier.

In addition, in the manufacturing method of the above embodiment, a semi-insulating semiconductor NI was first completely formed on a semiconductor substrate, and an active layer, etc. was formed in a groove provided in this, but a cladding layer, an active layer, etc. were formed on the semiconductor substrate. It is also possible to perform a manufacturing method in which, after sequentially forming the required semiconductor layers, selective etching is performed to leave all of these sitting conductors/+'S in a stripe shape, and then a semi-insulating semiconductor layer is selectively grown on all of them. In this case, it becomes easy to control the shape, thickness, etc. of the active layer.

Further, although the above embodiment is made of an InP-InGaAsP semi-crystalline phase material, the semiconductor material is not limited to this, and for example, gallium/arsenic (Ga, As
) Aluminum, gallium, arsenic (A6Ga) on the substrate
As) The present invention can be applied to a light emitting device using any semiconductor phase material, such as forming a striped region embedded in a semi-insulating semiconductor layer. (f) As described in detail, the present invention According to the research, current confinement is performed stably, reducing threshold current, blocking reactive current, and improving quantum efficiency significantly and with good reproducibility.Furthermore, it is possible to improve integration density even next fall. 6 possible

[Brief explanation of the drawing]

FIGS. 1(a) and (b) are cross-sectional views showing a conventional example of a semiconductor laser, FIG. 2 is a perspective view showing an embodiment of the present invention related to a semiconductor laser, and FIGS. 3(a) and (b) ld FIG. 2 is a 1θ one-view diagram illustrating the entire manufacturing process of the embodiment. In the figure, 1ltj: n-type ITIP substrate, 12 semi-insulating InP layers, 13 u n lJ'i InPm 1
cladding layer, 14 is a non-doped InGaAsP active layer, 15 is a p-type InP second cladding layer, 16 is a p-type InG
In the aAsP cap layer, 17 is a p-side electrode, and 18 is an n-side electrode. Figure 1 Figure 4

Claims (2)

[Claims] (1) A semiconductor light emitting device characterized in that a semi-insulating semiconductor layer is used as a semiconductor layer that defines a current path to a light emitting region. (2) The side end portion of the semiconductor layer provided between the semi-molar layer constituting the photoelectric conversion section and the electrode of the semiconductor layer is terminated by contacting the semi-insulating semiconductor layer. A semiconductor light emitting device according to claim 81!1, characterized in that: