JPS58220486A - Manufacture of semiconductor light emitting element - Google Patents

Abstract

PURPOSE:To obtain a preferable P-N junction surface and to obtain preferable element characteristics by continuously growing a P-N junction which has current narrowing function. CONSTITUTION:A p type InP layer 12 and an n type InP layer 13 are sequentially formed on an InP substrate 1. An SiO2 film 14 is then formed on the layer 13, and a groove forming window 15 is formed on the layer 14. Then, a V- shaped window 16 which reaches the substrate 11 via the window 15 is selectively formed. After the layer 14 is removed, an n type InP clad layer 17, an InGaAs P active layer 18 and a p type InP clad layer 19 are sequentially formed on the groove 16. At this time, an n type InP layer 17' and an InGaAsP layer 18 are sequentially formed even on the surface of the layer 13. According to this method, since the layers 12, 13 are continuously grown, air pollution, wet etching solution residue and P sublimation do not occur on the surface of the layer 12, but preferable P-N junction boundary can be obtained. Further, the layer 13 may be controlled to the thickness which does not produce a breakdown.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a method for manufacturing a semiconductor light emitting device, and in particular, it relates to a method for manufacturing a semiconductor light emitting device. The present invention relates to a method for manufacturing a gallium-arsenic-phosphorous (InGaAsP)/indium-phosphorus (Ink)-based double heterojunction semiconductor laser.

(2) Background of the technology Semiconductor lasers have many advantages such as relatively easy wavelength selection compared to other laser systems, small size, high efficiency operation, long life, fast direct deterioration, and single wavelength operation. There is optical transmission and
It is used as a light source in various practical processing systems.

In particular, it is possible to substantially reduce the width of the active region in a semiconductor laser having a buried structure, thereby reducing the one-value current and improving the differential quantum efficiency at each end facet of the semiconductor laser. See the effect.

(3) Prior Art and Problems FIG. 1 shows a complete cross-sectional view of a semiconductor laser in which a vsj-type groove f is formed in an In'p substrate and an InGaAsP active layer is buried in the groove. In the same figure, 1 is an NFI engineering nP substrate, 2 is a p-type InP layer, 3 is an n-type engineering nP cladding layer, 3
1 is. Type Ink layer, number is InGaAsP active layer, 5 is p
InP type cladding layer, 6 is shown on the p-side electrode, and 7 is shown on the n-side electrode, respectively.

In this semiconductor laser, a positive voltage of p*Il' is applied to the pole 6, a negative voltage is applied to the n-side electrode, and the p-type InP layer 2 and the n-type In2 layer 3 are
The carriers are injected into the active layer 4, which is embedded in the Kipano solution, through the p-n inverse diameter 7 of the current. The laser beam is confined within the surface of the active layer by the adjacent 7tn shoe cladding and p-type cladding layer 6. When the gain overcomes the loss due to sufficient injected carriers, laser light is generated from the active layer.

Next, with reference to FIGS. 2 to 5, a part of a conventional method for manufacturing a semiconductor laser having the above structure will be described. The same parts as the skin parts explained in Fig. 1 are indicated by the same symbols.

Refer to Fig. 2 (1) A p-type 1nP layer 2 is formed on the surface of the n-type nP substrate 1 using the liquid phase epitaxial growth method.
Refer to figure (1)) 8 layers of silicon dioxide (Sin) were formed on six sides of the p-type InP layer 2, and 80 layers of 5,102 layers were turned by applying a normal photo-etching method to form grooves. A window 9t is formed.

Refer to FIG. 4 (0) A wet etching method is applied to form a groove 10 of V*U with a depth reaching the substrate 1 through the window 9 for forming 4.

id) #Used as a mask for formation 7' (810
□Remove layer 8.

Refer to FIG. 5(e) An n-type InP cladding layer 3. InGaAs
A P active layer number and five p m I n P cladding layers are sequentially formed. At this time, the n-type nP cladding layer 3 and In(
) The aAaP active layer 4 is buried in the groove 10, but #1
0 There is also an n-type process on the external p-type InP12 surface n P 43'
And an InGaAgP layer 4' is grown. Further, the cross section of the active layer 4, which becomes the laser light emitting region, is thick at the center and becomes thinner toward the ends--a crescent shape.

In the conventional manufacturing method as described above, n-type nP clad!
-3 The surface of the p-type InP layer 2 was exposed to a burst of air 1 before the formation, and contaminants were attached to the surface of the p-type InP layer 2, and it was used to form the figure-7 groove 1. The etching solution remained on the surface of the p-type InP layer 2 and amounted to 7 tons.

Mayu, n m
Furthermore, the layer thickness of the n-type nP layer 3' is n
For example, the thickness of the n-type InP layer 3' is approximately 0 compared to the layer thickness Dμm at the thickest point of the Ni-type InP cladding layer 3 because it is determined by the layer thickness of the Ni-type InP layer 3.
4 (as thin as aml, pWInP layer 2 and n-type InPlii
Is it a disadvantage that breakdown is likely to occur between 3'?)
the law of nature.

(4) Purpose of the Invention The present invention solves all of the above-mentioned conventional problems, and provides a semiconductor light emitting device in which a sufficient p-n junction semiconductor layer is formed as a current confinement function, and breakdown does not occur during device operation. All methods provided.

(5) Structure of the Invention The above object of the present invention is to sequentially grow an InP layer having a first conductivity type and a second InP layer having a second conductivity type on an engineered nP substrate. Conductive acoustic InP7ii
This is achieved by selectively providing a recess with a depth that reaches the InP substrate from the i-surface, and filling the recess with a light-emitting region gold film.

(6) Implementation of the Invention An embodiment of the present invention will be described with reference to FIGS. 6 to 9.

See FIG. 6 () N-type engineered np substrate 11 doped with tin (Sn) and having a carrier concentration of 2 x l O,''' [sub-1]
The surface was doped with cadmium (Cd) by applying the liquid phase epitaxial growth method, and the carrier concentration was 5 x
p m I n P layer 12 'f of l O''(m-'')
n-type nP with a carrier concentration of 5 x 10''(m-') and further doped with Sn to a thickness of r l (μm).
The layers 13i1 (μm) are sequentially formed to a thickness of 13i1 (μm).

Refer to Figure 7 (b) OVD method is applied to the n-type nPH layer 13 by sputtering to form a layer 14 of 30 nm on its surface.
00 (A) thickness.

(0) Applying the normal photo etching method
Patterning of O, 414 is performed to form a window 15 for forming a groove.
form. Similarly, in this case, an ammonium hafluoride (NH, iF) solution is used as the etching solution.

(d) Wet etching is applied to form a groove on the NG-etched nP substrate 11 through the window 15. piInP layer 1
2. and n-type nP layer 13't-etched to a width of about 2
．． 5 [μm] and a depth of approximately 35 [μm]. Note that the etching solution in this case has a volume ratio of hydrochloric acid (HOt) niline (It (HA PO4) -3:
Use a mixture of 1.

Refer to Figure 8(,) 7'cSio is used as a mask for groove formation.
.

Layer 14i is removed by immersing it in NH, F solution.

(f) The i-phase epitaxial growth method is applied, and the carrier concentration of the V-shaped groove 16 doped with an is 2 x
l O"(crn-"), ndInP cladding layer 1'I with a thickness of 1.8 [μm] at its thickest point, I with a non-doped thickness of 0.17 [μm] at its thickest point
nGaAsPffla layer 1B, Cd-doped carrier concentration 5xlOI7 (cm"), 'p InP cladding layer 19 with a thickness of 2.7 [μm] at the thickest point.
are formed sequentially. At this time, the active layer 18 in the V-shaped groove
The cross-sectional shape of is thick at the center and becomes thinner toward the ends in a crescent shape, while the surface of the n-type InPld 13 also has an n-type InP layer 17' with a thickness of about 0.5 μm and a thick A thin InGaABp layer 1B' is successively grown.

(g) Subsequently, the liquid phase Evita kinial growth method is applied to form an n-type InGaAsP cap layer 20 doped with cd and having a carrier concentration of IXIO"(ctn-") on the surface of the p-type nP cladding layer 19. It is formed to a thickness of 0.09 [μm].

Refer to Fig. 9 (h) Apply the vapor deposition method to form a p-type nP cap layer 2.
A gap side electrode 21i of gold (A u )/zinc (Z n) is formed on the 0 surface to a thickness of 3000 (A), and nf
An n-side electrode 22 made of gold (Au)/Sn is formed to a thickness of 3000 (A) on the iInP substrate processing surface.

According to this embodiment, the p-n junction semiconductor layer, that is, the p-type I
Since the np layer 12 and the n-type nP layer 13 are continuously grown using the liquid phase epitaxial growth method, air contamination on the surface of the p-type InP layer 12, residual wet etching solution, and sublimation of P are prevented. It is possible to obtain a good p-n junction interface without causing such occurrence. Furthermore, since the thickness of the n-type nP layer 13 can be controlled to a level that does not cause breakdown, good device characteristics can be obtained.

The semiconductor light emitting device manufactured by this method had a 1-value current of 23 (mA) and leakage w and i of 0-50 (μA). The threshold voltage i of the device manufactured using the conventional manufacturing method is 3.
5 [mm], and the leakage current was αl-5 (mA). Therefore, it is possible to obtain a good p-n junction interface and obtain good device characteristics.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of essential parts of an embedded nGaAsP/InP semiconductor laser, FIGS. 2 to 5 are cross-sectional views of a conventional semiconductor laser manufacturing method, and FIGS. 6 to 9 are cross-sectional views of the present invention. It is a process sectional view showing one example. 1, lin...n[Engineering nP board, 2.12...-pfi
InP layer, 3, 17... n-type nP clad no, 3
', 13... nfiInP layer, 4.1B,... Eng nG
aAsP activity/m, 5゜19--p-type InP cladding layer, 6.2l-p141t electrode, Fig. 1 Fig. 2 Fig. 4 Fig. S Fig. 6 Fig. 7 Fig. 3 Male figure

Claims (1)

[Claims] An indium phosphide layer having a first conductivity type on the indium phosphide substrate, and an indium phosphide layer having a second conductivity type on the indium phosphide substrate.
A phosphorus layer is sequentially grown, a recessed portion having a depth reaching the indium-phosphorous substrate is selectively provided from the second surface of the indium-phosphorous layer covered with the second conductivity type metal layer, and a light-emitting region is provided in the recessed portion. A method for manufacturing a semiconductor light emitting device.