JPS6322478B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in methods for manufacturing semiconductor light emitting devices such as laser diodes or light emitting diodes.

Conventionally, laser diodes have a structure in which the active layer is surrounded by a cladding layer, such as BHLD.
(Buried Heterostructure Laser Diode)
BCLD (Buried Crescent Laser Diode) is known.

FIG. 1 is an explanatory side sectional view of the main part showing the structure of BHLD.

In the figure, 1 is an n-InP semiconductor substrate, 2 is a p-InP semiconductor substrate, and 2 is a p-InP semiconductor substrate.
-InP current blocking layer, 3 is n-InP cladding layer, 4
is InGaAsP active layer, 5 is p-InP clad layer, 6 is
is a p-InGaAsP contact layer, 7 is an n-side electrode,
8 indicates a p-side electrode.

By the way, in order to manufacture this laser diode, a groove reaching from the surface to the substrate 1 is formed at the stage where the p-InP current blocking layer 2 is grown by applying the liquid phase epitaxial growth method to the n-InP semiconductor substrate 1. After that, the liquid phase epitaxial growth method is applied again to grow the n-InP cladding layer 3, the InGaAsP active layer 4, the p-InP cladding layer 5, and the p-InGaAsP contact layer 6. When this technique is adopted, liquid phase epitaxial growth is performed twice, which has the disadvantage that the manufacturing yield is extremely low.

The present invention provides a method for manufacturing a semiconductor light emitting device that can be completed by liquid phase epitaxial growth in one step, and will be described in detail below.

FIGS. 2 to 4 are side cross-sectional views of the main parts of the apparatus at key points in the process for explaining one embodiment of the present invention.Next, referring to these figures, Describe.

Refer to Figure 2 (1) The width of the n-InP substrate 11, for example, approximately 2 [μm], is etched using photolithography and etching techniques.
A groove 11a having a depth of, for example, about 1.5 [μm] is formed.

See Figure 3 (2) Applying the liquid phase epitaxial growth method, p-
The InP current blocking layer 12 has a thickness of, for example, approximately 0.1 outside the groove.
Grow to [μm]. In this way, the thickness within the groove will be approximately 0.5 [μm].

See Figure 4 (3) Following the above steps, the n-InP cladding layer 1 is
3 is grown to a thickness of, for example, about 0.1 [μm] outside the groove. Due to this, the thickness inside the groove is approximately 0.5 [μm]
become.

(4) An In _1-x Ga _X As _1-y P _y active layer 14 is formed in the groove to a thickness of about 0.15 [μm], for example.

(5) The p-InP cladding layer 15 is grown to a thickness of, for example, about 1 [μm] outside the groove.

As a result, the groove 11a is completely filled and the surface becomes flat.

(6) The p-In _1-z Ga _z As _1-s P _s contact layer 16 is grown to a thickness of, for example, about 0.5 [μm]. This completes the series of continuous epitaxial growth.

(7) P-side electrode 17 and n-side electrode 1 using normal techniques
Form 8 and complete.

In this way, in the present invention, all semiconductor layers are grown by one continuous epitaxial growth method.

By the way, according to the above embodiment, p-
An InP current blocking layer 12 is formed and an n-InP cladding layer 13 is formed thereon.
Since a reverse bias will be applied to the pn junction, the current will be blocked and will flow horizontally in the direction shown by the arrow in the figure, but this will not affect the operation in any way. Also, due to the difference in diffusion potential, compared to current injection from the p-InP layer 15 to the n-InP substrate 11, the p-InP
Since current injection from layer 15 to active layer 14 is performed more easily, current can be efficiently injected into the active layer.

FIG. 5 is a side cross-sectional view of a main part of a semiconductor light emitting device for explaining another embodiment, and the same symbols as those used in FIG. 4 indicate the same parts or have the same meanings. shall be.

In this embodiment, the n-InP cladding layer 13 in FIG. 4 is omitted by forming a p-InP cladding/current blocking layer 12'.
In this case, current flows from the side surface of the active layer 14 as shown by the arrow.

FIG. 6 is a side cross-sectional view of a main part of a semiconductor light emitting device for explaining another embodiment, and the same parts as those explained with reference to FIG. 4 are indicated by the same symbols.

In this embodiment, an n-InGaAsP guide layer 13' is formed on the p-InP current blocking layer 12, and this guide layer 13' has a different composition from the active layer 14 and has a band gap. is taken to be about 0.1 [eV] large.

In this way, from the active layer 14 to the guide layer 1
Since the amount of light seeping out to 3' increases, the light emitting area becomes wider, making it possible to increase the output and make the light emitting shape circular.

FIG. 7 is a side cross-sectional view of a main part of a semiconductor light emitting device for explaining another embodiment, and the same parts as those explained with reference to FIG. 4 are indicated by the same symbols.

In this embodiment, the composition of the p-InP cladding and current blocking layer 12' shown in FIG. 5 is changed as explained with reference to FIG. 6 to form a p-InGaAsP guide and current blocking layer 12''.

Needless to say, in each of the embodiments described above, the substrate 11 also serves as a cladding layer, and in each embodiment, the conductivity types, that is, n-type and p-type, may be reversed, and further, In addition, without introducing impurities into the current blocking layer, for example, InP,
A high resistance layer such as InGaAsP may also be used.

In any of the embodiments described above, it goes without saying that the epitaxial growth for forming each required semiconductor layer can be accomplished by one continuous growth.

As can be seen from the above explanation, according to the present invention, a groove is formed in the substrate from the beginning, and then each semiconductor layer is epitaxially grown continuously, and a current blocking layer is formed at the lowest part of the groove, separated from other regions. , an active layer buried in the groove, and a cladding layer in contact with the active layer.
Since epitaxial growth only needs to be performed once, manufacturing yield is improved.

[Brief explanation of the drawing]

FIG. 1 is an explanatory side cross-sectional view of the main part of a conventional example, and FIGS. 2 to 4 are side cross-sectional views of the main part of a semiconductor light emitting device at important process points for explaining an embodiment of the present invention.
5 to 7 are sectional side views of essential parts of a semiconductor light emitting device for explaining different embodiments of the present invention. In the figure, 11 is a substrate, 11a is a groove, 12 is a current blocking layer, 13 is a cladding layer, 14 is an active layer,
15 is a cladding layer, and 16 is a contact layer.

Claims (1)

[Claims] 1. Forming a groove in a semiconductor substrate, and then successively forming a current blocking layer, an active layer, and a cladding layer in that order on the surface of the semiconductor substrate and the bottom of the groove in one growth step. A method of manufacturing a semiconductor light emitting device, characterized in that: