JPS6043880A - Manufacture of semiconductor light-emitting device - Google Patents

Abstract

PURPOSE:To manufacture the title device, a clad layer thereof has a necessary sectional shape, the surface thereof is formed flatly and an active layer thereof is also flattened, with excellent productivity, by growing one part of the clad layer on a semiconductor base body while inhibiting a meltback at the large degree of supercooling and growing it at the small degree of supercooling. CONSTITUTION:A P type Ga1-xAlxAs layer 2 and an N type GaAs layer 3 are grown on an N type GaAs substrate 1 through LPE method, and a striped groove is formed to the surface of the layer 3. Each semiconductor layer is grown on the base body through the LPD method. When a first section 4a in a clad layer 4 is grown at the large degree of supercooling at that time, the meltback of the shoulder, etc. of the striped groove is inhibited. An indentation remains in the groove section in the surface under the state, but the clad layer 4 having a flat surface is formed when a residual section 4b is grown at the small degree of supercooling. Consequently, an active layer 5 and each layer on the layer 5 are also flattened. A P side electrode 8 is formed on a P type GaAs cap layer 7 and an N side electrode 9 on the back of the substrate 1, thus completing a light-emitting element.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a method for manufacturing a semiconductor light emitting device, and more particularly to an improvement in a liquid phase epitaxial growth method for forming a double \terojunction structure on a semiconductor substrate provided with striped areas.

+bl Technical background In systems that use light as an information signal medium for many commercial and consumer fields, semiconductor light emitting devices are the most important component, and are essential for achieving the desired wavelength band and Many efforts have been made to improve the basic characteristics of semiconductor light emitting devices, such as stable single fundamental zero-order transverse mode oscillation, single longitudinal mode oscillation, reduction of threshold current, improvement of source efficiency, and increase in output. There is.

(cl. Prior Art and Problems) Among conventionally known semiconductor light emitting devices, there are many structures in which a striped groove is provided on a semiconductor substrate and a double depression is formed on the semiconductor substrate.

FIG. 1 is a cross-sectional view showing an example of a semiconductor light emitting device having such a structure, in which numeral 1 indicates a nu-arsenide gallium cladding layer, 5
is an n-type GaA7As active layer, 6 is a p-type GaAAAs cladding layer, 7 is a p-type GaAs cap layer, and 8 is a pfl
ll electrode, and 9 is an n-side electrode. In this structure, n
While the GaAtAs cladding layer 4 is sufficiently thick in the stripe region, it is thin outside the stripe region and the GaAs original absorption layer 3 is provided, making the GaA7SA 3
Outside the stripe region, light seeping out from the active layer 5 is exposed to GaA.
Since the light is absorbed by the s-light absorption layer 3, stable transverse mode resonance occurs only in the stripe region.

In this semiconductor light emitting device, p
A type GaALAs layer 2 and an n-type GaAs layer 3 are first grown epitaxially, and then, after forming striped grooves penetrating the layers 2 and 3 and extending to the substrate 1, the n-type GaA7As cladding layers 4 to p are grown. A GaAs cap layer 7 is epitaxially grown.

When growing a semiconductor layer on a semiconductor substrate having irregularities such as the grooves by liquid phase epitaxial growth (hereinafter referred to as LPE), if the degree of supercooling of the growth solution is small, the growth rate will be slow and meltback will occur. Strong (Although it appears, the growth rate is relatively high in concave areas of the substrate surface and the growth surface is likely to be flattened.If the degree of supercooling of the growth solution is large, the growth rate will be fast and meltback will be suppressed, and the growth surface will be flattened.) is close to the shape of the substrate surface.

In the semiconductor light emitting device shown in FIG. 1, in order to obtain stability in the transverse mode, the upper surface of the 0aAtlLs active layer 5, and therefore the n-type CIaAtAs cladding layer 4, is flat, and the upper surface of the diagonal layer is flat. The thickness within the stripe area of No. 4 is required to be greater than the original seepage width and extremely thin outside the stripe area. LPE the cladding layer 4 into this shape.
In order to achieve growth, the degree of supercooling must be reduced, but if the degree of supercooling is shifted to a small value, as mentioned above, meltback will appear strongly, and the striped debris indicated by the symbol -@lO in Figure 1 will appear. The portion becomes dull, leading to disturbance of the stripe shape and deterioration of laser characteristics.

In this situation, 0aAAA8S Kuyatsu Clad LJPE
Compared to growth, the degree of supercooling for growth tolerance is the same as the above two contradictory factors.
It is determined based on a balance of factors, but the conditions are within an extremely narrow range, making it difficult to implement and having poor reproducibility.

(Purpose of the Invention) The present invention provides a semiconductor light emitting device in which striped grooves are formed on a semiconductor substrate and a double/terojunction structure is epitaxially grown on the semiconductor substrate to obtain a guiding effect.
It is an object of the present invention to provide a manufacturing method that allows easy manufacturing with good reproducibility.

(el) Structure of the Invention The object of the present invention is to form stripe-shaped grooves in a semiconductor substrate, and to form a part of the cladding layer on the semiconductor substrate into a cylinder.
This is achieved by a method for manufacturing a semiconductor light emitting device, in which liquid phase epitaxial growth is performed with a degree of supercooling of , and then the remaining portion of the cladding layer is grown with a second degree of supercooling that is smaller than the first degree of supercooling.

In other words, according to the present invention, a part of the cladding layer is first grown on the semiconductor substrate with a high degree of supercooling to suppress meltback, and then a part of the cladding layer is grown with a small degree of supercooling so that the top surface is flat and the inside and outside of the stripe grooves are formed. Complete the cladding layer with a large thickness ratio. The active layer subsequently grown on this cladding layer becomes flat, making it possible to manufacture semiconductor light emitting devices with good characteristics with high productivity.

(fl) EXAMPLES OF THE INVENTION The present invention will be described in detail below with reference to the drawings, starting with Example 1.

FIG. 2 (a+ to iel are cross-sectional views showing states during the main manufacturing process l of an embodiment in which the semiconductor light emitting device described above with reference to section 1 is manufactured by applying the present invention.

n iJI GaAs substrate l, p fJI Ga
l -xAtxAs layer 2, for example x=0.3. Thickness 0.
Then, an n-type GaAs layer 3 is grown to a thickness of, for example, about 1 [μm] by the LPg method.

Next? 2 [μIIL
) and a stripe-shaped groove having a width of, for example, about 3 to 5 [μm]. (Figure 2+a) Reference 9 This groove is for example a (100)
By using a mixed solution of water (H, 0) = 1:8:8 as a surface, an inverted trapezoid as shown in the figure is formed.

The following semiconductor layers are successively epitaxially grown on the semiconductor substrate by the LPH method. However, after maintaining the temperature at 805° C. for about 1 hour to dissolve the solution, the temperature was lowered at a cooling rate of 0.5 C'C/wt:I.

(1) First portion 4a of n-type Oa+-xA7xAs clad layer 4 (see Figure 2 (bl)) Charge amount of growth solution; Ga: C1aA, s:kt:0a2Te3=4
[g:l: 11]D4[mg:]: 5616
(+ng): 0.4 (saturation temperature of growth solution; 80t
3 ('C) Growth start temperature; 798 [:'C:] Supercooling degree; 2 ['C] Growth time; 15 [seconds] Growth thickness (on flat surface); Approximately 0.1 [μm] of growth layer A
A composition ratio;
4 (g): 108.72 [mg): 5.59
2[1+ng) :0.4 (:mg) Growth solution saturation temperature; 798.4 (:'C) Growth start temperature: 797
．． 9 (:°C) Degree of supercooling: 0.5 [:°C) Growth time: 30 [seconds] Growth thickness (on flat surface) Approximately 0.2 [μm] ht of growth layer
Composition ratio; 'x=0.45Full' n-type Gat
-xAAxAs active layer 5 (Figure 2 below (see mountain) Charge amount of growth solution; Ga:GaAs:Al!+:GazTe3= 4 Cg
) :20Kmg'] :1.60[mg] :0.15
Cmg) However, for the growth solution with an active layer of 5 or less, G
The amount of charge of aAs exceeds the amount that can be dissolved.

Growth time; 5 [seconds] [IVl p @ Ga 5-xAtxA, s Charge amount of cracked layer 6 growth solution; Ga: GaAs; At: Mg = 4 [g: l: 16o (mg': l: 6.0
[mg]: 1.2 [mg] Growth time: 10 [minutes] Growth thickness: Approximately 2.0 [μm] At composition ratio of growth layer: X=0.45 (Vl p type () a As cap Charge amount of layer 7 growth solution Ga: GaAs: Ge = 4 [g): 240 [:tng): 80 (mg) Growth time: 3 [minutes] Growth thickness: Approximately 2.0 [μm] Above implementation By growing the first portion 4a of the cladding layer 4 by LPE with a large degree of supercooling as in the example, meltback at the shoulders and the like of the stripe grooves is suppressed.

In this state, as shown in the figure, either a depression is left at the groove part on the upper surface, or the remaining part 4b is grown by LPE with a small degree of supercooling, so that the total growth thickness of the flat part is about 0.3 [μm]. The upper surface is flat with a small amount of growth, and the ratio of the inside and outside thickness of the stripe is 23 [μm]:Q, 3 [μm].
A cladding layer 4 having a thickness of about 100 m] is formed. - Since the upper surface of the n-type GaAAAs cladding layer 4 is flat, the active layer 5 and each layer grown thereon are also flat.

Next, a semiconductor light emitting device is completed in which p layers are stacked on the p-type GaAs character layer 7. (See FIG. 2, 1cl) In the embodiment described above, the shape of the groove is an inverted trapezoid, but the present invention can be similarly applied even if the shape of the groove is a square shape or another shape. Further, in the above embodiment, Ga
Although an As-GaAtAs-based semiconductor layer is grown, the present invention can be applied to LPE growth of other semiconductor materials, such as Ink-InGaAsP-based, to obtain similar effects.

As described in detail, according to the present invention, the cladding layer has the required cross-sectional shape and the surface is flat, and the active layer is also flat, resulting in excellent properties such as a stable single transverse mode. It becomes possible to manufacture a semiconductor light emitting device with characteristics with good productivity.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a semiconductor light emitting device to which the present invention is applied, and FIG. 2 ta+ to tel are sectional views showing an embodiment of the present invention. In the figure, 1 is an n-type GaAs substrate, 2 is a pf
JI GaAtAs layer, 3 is an n-type GaAs layer, 4 is an n-type GaA virtual cladding layer, 4a and 4b are parts of the cladding layer 4, 5 is an n-type ()aAtAs active layer, 6 is a p-type GaA
A7As cladding layer, 7 a p-type GaAs cap layer, 8 a p-side electrode, and 9 an n-side electrode.乎II￥] Rod 2 Figure rod 2 Figure (d

Claims (1)

[Claims] Striped grooves are formed in a semiconductor substrate, a portion of the cladding layer is liquid phase epitaxially grown on the semiconductor substrate at a first degree of supercooling, and then the remaining portion of the cladding layer is grown at the first degree of supercooling. A method for manufacturing a semiconductor light emitting device, characterized in that the semiconductor light emitting device is grown with a second smaller degree of supercooling.