JPS62152185A - Light-emitting element - Google Patents

Abstract

PURPOSE:To prevent reflection from an end surface of beams in an LED, and to obtain spontaneous emitted beams by roughening one of the end surfaces of the end-surface light-emitting type LED. CONSTITUTION:In an end-surface light-emitting type LED 11, in which a V groove is buried onto an n-InP substrate 15 and which has InP/InPGaAs hetero- structure, a nonreflective coating is applied on a light-emitting end surface 21 in the same manner as conventional examples, and an end surface 13 on the side reverse to the end surface 12 is roughened, or an inclined plane 14 including an active layer 17 is roughened. Consequently irregular reflection is formed and the reflectivity lowers, and since the end surface 12 consists of a nonreflective film, the intensity distribution of light from the LED becomes of a Gauss curve shape, and intensest beams enter an optical fiber 26. HF: HNO3=1:1 is used for InGaAs 22 and HCl is employed for InP 15 as an etching liquid for surface roughening, thus bringing a complete nonreflective state.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] An edge-emitting type light-emitting diode is characterized in that the end face opposite to the light-emitting end face is etched to have a rough surface, and the light-emitting end face is coated with a non-reflection coating.

[Industrial application field]

The present invention relates to a light emitting device, and more specifically, to prevention of edge reflection of light within a chip of an edge emitting type light emitting diode.

[Conventional technology]

In the first developed light emitting diode (LED) shown in FIG. 4, light 31 was emitted from a window 34 provided on the surface 33 of the light emitting diode.

In a laser diode, the end surface of the chip is finished with a mirror finish and the light is reflected inside the chip to resonate and amplify the light to extract the light. 41, an anti-reflection coating film (Ant
i-Reflection+ (also referred to as R film) is attached to create a state in which no light is reflected inside the diode, and a spontaneous emission light configuration is adopted in which light 44 is extracted without amplifying the light. Note that the edge-emitting diode differs from a conventional light-emitting diode in that it emits light not from the surface 45 but from the 6::'1 surface 42.

[Problem that the invention seeks to solve]

Conventional techniques for preventing light from being reflected at the end faces within a chip have been carried out by applying a non-reflective coating to the end faces, as described above. However, with this method, the reflectance of the end face varies due to variations in the thickness of the film applied to the end face, and a completely non-reflective coat 1-1
It is quite difficult to attach 1ff.

Figure 6 shows the film thickness (horizontal axis) and light reflectance % of the non-reflective coating film.
(vertical axis). Light reflection 0.1
% or less depends on the thickness of the anti-reflection coating film, its refractive index, etc., but when it comes to controlling the film thickness, the variation must be kept within about 90 people, and such a narrow A unit A light emitting diode with excellent characteristics cannot be obtained unless the film is tightly attached within the range of .

The present invention was created in view of these points, and the object of the present invention is to roughen the end face by chemical etching before applying the anti-reflection coating film, thereby creating a completely non-reflection state.

[Means for solving problems]

1 and 2 are perspective views of the first and second embodiments of the present invention,
FIG. 3 is a cross-sectional view of the edge-emitting type light emitting diode of FIGS. 1 and 2. FIG.

In the first embodiment of the present invention, the end surface 13 of the edge-emitting type light emitting diode 11 opposite to the light-emitting end surface 12 provided with the anti-reflection coating is roughened, and in the second embodiment, the active layer is roughened. A flat surface 14 including the light emitting end surface 12 is inclined at a certain angle with respect to the light emitting end surface 12, and the inclined plane 14 is made a rough surface.

[Effect]

In the present invention, the end surface opposite to the light emitting surface of the light emitting diode is roughened by chemical etching of the end surface to generate diffuse reflection and reduce the reflectance at the end surface. This creates a non-reflective state.

〔Example〕

FIG. 3 shows a heterostructure (V-grooved) in which a V-groove is buried in a substrate, which is an example of the edge-emitting type light-emitting diode (hereinafter simply referred to as a light-emitting diode) 11 shown in FIGS. 1 and 2.
5ubstrate Buried-heterost
structure.

νSR) is shown, and in the figure, 15 is an n-Inp substrate, 16 is an n-1nP layer\17 is n-11GaAsP
Active layer 18 is p-[nr' layer (thickness, 8 tlm
), 19 is an n-InP layer (thickness 0.2 pm),
20 is an n-InGaAsP layer, 21 is a p-1nP layer (thickness 2.5 μm), and 22 is a p-InGaAsP layer (thickness
0.5 μm), 23 is a p electrode, 24 is an n electrode, and the light emitting diode 11 has a 300 μm opening and a height of 100 μm±20
．． crm, the active layer 17 has a thickness of 0.15 μm1 in the central part.
The width is 2 to 2.5 .mu.m, and the upper width of the groove is 5 .mu.m, and this structure and its operation are known.

In the first □ second embodiment of the present invention, the light emitting end face 12 is coated with an anti-reflection coating film as in the conventional example, and the opposite end face is made rough. In the first embodiment, all end faces parallel to the light emitting end face 12 are roughened. In the second embodiment, the plane including at least the active layer 17 is inclined at a certain angle with respect to the light emitting end face 12, and the surface of this inclined plane is made into a rough surface 14. In FIG. 1, reference numeral 25 indicates light emitted from the light emitting diode, and reference numeral 26 indicates an optical fiber that couples with the light emitting diode and transmits the light 25. The reason why the anti-reflection coating film is provided on the end face 12 is to make the distribution of light reflection intensity from the light emitting diode into a Gaussian curve shape so that the highest intensity light enters the optical fiber 26.

An example of roughening the end surface 13 of the present invention is by etching, and the etching solution is
NO3 (1: 1), ■H Zheng, ■IIF-tlNO
3+ 1lci! Three types are used. In the case of ■, the InGaAsP layer on the end surface is roughened, and in the case of ■, the InGaAsP layer on the end surface is roughened.
The P layer is destroyed, and in the case of ■, the InGaAsP layer, InP
Both layers have been destroyed. This utilizes the difference in etching rate of each layer as described above. According to the inventor's confirmation, it is possible to create a completely non-reflective state in the cases of ■ and ■, and although there was some variation in the case of ■, it is much improved compared to the conventional example. It is.

Note that when roughening the end face, methods other than chemical etching, such as gas, plasma, and ion etching, are equally effective.

〔Effect of the invention〕

As described above, according to the present invention, by making one of the end faces of an edge-emitting type light emitting diode rough, end face reflection of light within the light emitting diode is prevented, and spontaneous emission light can be obtained. There is.

Note that the light emitting diode is not limited to the structure shown in FIG.

[Brief explanation of drawings]

Fig. 1 is a perspective view of the first embodiment of the present invention, Fig. 2 is a perspective view of the second embodiment of the invention, Fig. 3 is a sectional view of the VSB, Figs. 4 and 5 are perspective views of the conventional example, FIG. 6 is a diagram showing the relationship between the film thickness and reflectance of the AR film. 1 to 3, 11 is a light emitting diode, 12 is a light emitting end face, 13 is a rough surface, 14 is an inclined rough surface, 15 is an n-1nP substrate, 16 is an n-InP layer, 17 is a p- InGaAsP layer (active layer) 18 is p-In
P layer, 19 is n-1nP layer, 20 is n-1nGaAsP layer, 21 is p-1nP layer, 22 is p-1nGaAsP Nt%, 23 is p-electrode, 24 is n-electrode, 25 is light, 26 is optical fiber be. Agent Patent attorney Akifuku Kuki Agent Patent attorney Yoshio Suga No. 1 Inventor expense cell 1,000 mouths Figure 1 Liu plane mouth Figure 3 Conventional 4PJ floor plan No. 4 prisoner 77 Go to Note 7L” 21 Lang-15 Seirai-hiki V head diagram Figure 6 I Error 54 Diko 1 Iri day Figure 7 1985 Patent application No. 292210 21 Title of the invention Light-emitting device 3, Relationship with the amended person case Patent applicant address: 1015 Kamiodanaka, Nakahara-ku, Yozaki-shi, Kanagawa Prefecture Name: Fujitsu Ltd. 4 Agent address: 1-31-3-808-6 Shinjuku, Shinjuku-ku, Tokyo
, Target of correction Drawing 1 GO = TO /7. '% 1=
・ -尤糎4If112 Shimoto; Menkuyoto 9 Tetsui Ikuri Oblique Nell U Fig. 1 Book, Knees, θ1 Desk Clothes, Fig. 2, Pleasure? November obscene 7 4th wa 1 i 11 (+ll MCI! 1 5th figure body movement (%) C is so and 6th figure

Claims (2)

[Claims] (1) In the edge-emitting type light-emitting diode (11), the surface of the end surface opposite to the light-emitting end surface (12) is a rough surface (13), and the light-emitting end surface (12) is coated with an anti-reflection coating. A light-emitting element that (2) A plane including at least the active layer (17) on the end face opposite to the end face (12) is a surface inclined at a certain angle with respect to the end face (12), and the surface is a rough surface (14). The light emitting device according to scope 1.