JPS62154674A - Junction type semiconductor light emitting device - Google Patents

Abstract

PURPOSE:To diverge or converge the light emitted from the pn junction within the pole type projection in accordance with application of a light emitting device and expand the application range of light emitting device by providing a lens to the top surface of the pole type projection or to the area just under the pole type projection among the surface opposed to the surface in the side of pole type projection at the flat surface. CONSTITUTION:A junction type semiconductor light emitting device is formed by a flat part B, a pole type projection P provided on the single surface of said flat part B, a p side electrode E1 provide at the side circumference surface of pole type projection P and on the upper surface of flat part B, an n side electrode E2 provided at the lower surface of flat part B and an insulating film 10 provided between the upper surface and the electrode E1 of the flat part B. A cylindrical pn junction PN1 extending in the perpendicular direction to the flat part B is formed within the pole type projection P, but the pn junction PN2 extending in the parallel direction to the flat part B is not formed in the flat part B. In the light emitting device of such structure, the top surface of pole type projection P is integrally formed in the shape of convex lens f1 in order to converge the light emitted from the pn junction PN1.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a junction type semiconductor light emitting device that can be used as a light emitting diode or a semiconductor laser, and particularly relates to a junction type semiconductor light emitting device that can be used as a light emitting diode or a semiconductor laser. Consisting of a protrusion and an electrode provided at any location on the flat plate part and the columnar protrusion, it has at least a pn junction within the columnar protrusion that extends in a direction perpendicular to the flat plate part, and emits light emitted from the pn junction. Alternatively, the present invention relates to a junction type semiconductor light emitting device that is focused.

[Conventional technology]

A light-emitting element that emits light in a direction perpendicular to the substrate can be easily coupled with an optical fiber, and can also be used as a surface emitter to form a one-dimensional or two-dimensional array structure.
A: Since they are expected to be used in various applications such as information equipment, development has been progressing in the research field of semiconductor lasers and light emitting diodes, and in recent years, a wide variety of products have been put into practical use.

[Problem that the invention seeks to solve]

A typical structural example of the junction type semiconductor light emitting device is as shown in FIG. Peripheral surface and flat plate part (
The p (!1.!l electrode (El) provided on the - side of B) and the n (II!l electrode (E
2). Inside the columnar projection (P), there is a pn junction PNI extending perpendicularly to the flat plate part (B).
However, within the flat plate part (B), there is a pn junction 42 extending in a direction parallel to the flat plate part (B). Then, a current is injected between the electrodes (El) and (E2) so that light in a direction perpendicular to the flat plate part (B) can be obtained by the pn junction PNI.

Incidentally, such a light-emitting element originally has better light convergence than a light-emitting element having a structure in which light is emitted parallel to the flat plate portion, and can be efficiently coupled to an optical fiber. However, even so, the emission angle θ of light emitted from the columnar projection (P) is large to some extent due to the difference in refractive index between the top surface and air.

Therefore, in order to further improve the coupling efficiency with the optical fiber, it is preferable to further improve the light convergence. vice versa,
For example, when a light emitting element is used in a display device or the like, it is necessary to further increase the emission angle θ to spread out the light so that the display can be viewed from many directions. However, the reality is that no specific means for diverging or converging light emitted from a light emitting element having the above-described structure has yet been proposed.

Therefore, in the junction type semiconductor light emitting device having the structure described above, which is the light emitting source, it is very important to diverge or focus the light from the pn junction PNI in the columnar projection (P) depending on the purpose of use of the light emitting device. It is.

Therefore, an object of the present invention is to provide a junction type semiconductor light emitting device that can diverge or focus light emission from a pn junction in a columnar projection depending on the use of the light emitting device.

[Means for solving problems]

The object consists of a flat plate part, a columnar protrusion provided on one side of the flat plate part, and an electrode provided at any location on the flat plate part and the columnar protrusion. In a junction type semiconductor light emitting device having a p-n junction extending from the 35 p-n junction to the top surface of the columnar protrusion or the surface of the flat plate part that is opposite to the surface on which the columnar protrusion is formed, a portion directly under the columnar protrusion is applied. This is achieved by a junction type semiconductor light emitting device provided with a lens for diverging or focusing light emission.

The lens described in 1f.2 may be formed from a part of the light emitting element, or may be formed from an organic or inorganic material different from the constituent material of the light emitting element. In the former, the top surface of the columnar projection or the lower surface of the flat plate portion, which is directly under the columnar projection, is formed into a lens shape. In the latter, a lens made of a material different from that of the light emitting element is attached to the predetermined location, and the material is transparent to light emitted from the pn junction in the columnar protrusion. , and there is no particular restriction as long as the purpose of the present invention can be achieved; for example,
There are organic materials such as epoxy resins, and inorganic materials such as SiO□ and SiNx, especially epoxy resins (especially clear epoxy resins, which are epoxy resins that transmit light in the approximately 0.5 to 1.2 p-band). is suitable.

By the way, the junction type semiconductor light emitting device as described above has a pn junction (pn junction PN
1'), and the pn junction (pn junction PN 2 ) extending parallel to the flat plate part does not exist, or even if it does exist, it emits as much light as possible. It is preferable to take various measures to avoid this. For example, one idea is to mask the upper surface of the flat plate to diffuse impurities when forming a pn junction in the columnar protrusion and the flat plate, so that the pn junction PN2 extending horizontally within the flat plate can be effectively It is possible to obtain a junction type semiconductor light emitting device that is not formed in a conventional manner.

In the present invention, it is preferable to use a junction type semiconductor light emitting device having such a structure.

[Effect]

In the junction type semiconductor light emitting device of the present invention, the pn
Diverging or focusing the emission from the junction PNI.

〔Example〕

Hereinafter, the junction type semiconductor light emitting device of the present invention will be explained based on the drawings.

FIGS. 1(a) and 1(b) show an embodiment of the junction type semiconductor light emitting device of the present invention. The junction type semiconductor light emitting device of the present invention includes:
A flat plate part (B), a cylindrical protrusion (P) provided on one side of the flat plate part (B), and a p-side provided on the side peripheral surface of the cylindrical protrusion (P) and the upper surface of the flat plate part (B). The electrode (Ill), the n-side electrode (E2) provided on the lower surface of the flat plate part (B), and the flat plate part (B)
) is interposed between the top surface of the insulating film (1) and the electrode (El).
0). Inside the cylindrical projection (P), there is a cylindrical pnn extending perpendicularly to the flat plate part (B).
Although a junction PN1 is formed, a pn junction PN extending in a direction parallel to the flat plate part (B) is formed in the flat plate part (B).
2 is not formed. In a light emitting element with this structure,
In Fig. 1(a), the top surface of the cylindrical protrusion (P) is shaped like a convex lens (fl) in order to focus the light emission from the pn junction PNI.
) is integrally formed. As is clear from the figure, the lens (
The pn junction 1'N1 does not extend within the fl).

With this structure, the light emitted from the pn junction PNI is focused by the convex lens (fl), and the coupling efficiency with the optical fiber is further improved. The light emitting element shown in Figure 1(b) is one in which the top surface of a cylindrical projection (P) is integrally formed into a concave lens shape (f2), and the pn junction PNI is a concave lens (f2) similar to that shown in fat. does not extend to the surface of the light emitting element, and the light emitted is diverged by the concave lens (f2), which is effective when this light emitting element is used in, for example, a display device.

In order to form the top surface of the cylindrical projection (P) into the above-mentioned convex lens shape, when forming the cylindrical projection (P), a circle is formed on the substrate (or on the epitaxial layer if an epitaxial layer is provided on the substrate). When a resist is formed in a convex shape (concave in the case of a concave lens) at the top surface of the columnar projection CP) and the substrate is etched using, for example, reactive ion etching, the resist will be Since the etching is performed little by little, the top surface of the cylindrical projection (P) is formed into a convex shape. After that, impurities such as zinc are diffused to form a pn junction.
By forming I and providing electrodes ([fl) and (E2) at predetermined positions, a junction type semiconductor light emitting device that can be used as a light emitting diode can be obtained.

The light emitting device shown in FIGS. 2(a) and 2(b) has a flat plate part (B
The part directly under the cylindrical protrusion CP") on the lower surface of ) is integrally formed into a lens shape. (a) is a convex lens (f3) for converging light emission, and (b) is a concave lens for diverging light. (r4).In this example, since light is emitted from the lower surface of the flat plate part (B), for example, GaAs, which is not a light-transmissive material for the emission wavelength, is used as the substrate. If an epitaxial layer is provided on top of the epitaxial layer, it is necessary to scrape the substrate down to the epitaxial layer.Also, by providing a reflective mirror or reflective film (F) on the top surface of the cylindrical projection (P), the pn junction P
Of the light emitted from the NI, not only the light traveling toward the lower surface of the flat plate portion (B) but also the light traveling toward the tip of the cylindrical projection (P) is reflected and emitted from the lower surface of the flat plate portion (B). This makes it possible to use light effectively.

In the above embodiments, the cylindrical projection (P) or the flat plate portion (B)
1 and 2, it is possible to form a lens from another organic or inorganic material and to
It may be installed at the predetermined position shown in the figure. Flat plate part (B)
When installing a lens on the lower surface of the lens, it may be installed directly at the installation location, or a groove capable of accommodating the lens may be formed in advance in the flat plate portion (B) and the lens may be attached to the groove.

Note that in the present invention, a Fresnel lens may be used instead of a convex lens when converging light.

In the present invention, the electrodes (El) and (E2) are not limited to the positions and sizes shown in the examples, but are provided at any position and with any size as long as the purpose of the present invention can be achieved. be able to. Further, there are no particular restrictions on the method of forming the pn junction, such as impurity diffusion method,
The epitaxial vapor phase growth method of p (or n) type semiconductor layer and n (or p) type semiconductor layer (in this case, heterojunction is also possible) or other methods may be used.

In the present invention, a pn junction PNI that contributes to vertical light emission is used.
Since the length of the columnar projection (P) can be increased by increasing the height of the columnar projection (P), it is preferable that the height of the columnar projection (P) is at least 2-1, particularly at least 10p. It is possible to form columnar protrusions (P) on the surface of a semiconductor wafer by, for example, a reactive ion etching method. A light emitting device can be easily manufactured.

Regarding the present invention, the "vertical direction" in the columnar projection (P)
There is no need to limit the meaning of the term to mean only a direction perpendicular to the flat plate part (B) at an angle of 90°;
This also includes cases where the angle of inclination is somewhat larger or smaller. For example, the entire columnar protrusion (P) or only the coaxial cylindrical pn junction pHN formed inside it may be formed into a truncated conical shape with a larger diameter at the bottom to make it easier to couple to the optical fiber. It is also possible to focus the output light into a truncated conical shape, which is the opposite of the above, to emit more light +tJ! depending on the purpose of use. , you may do so.

The light-emitting materials used in the junction type semiconductor light-emitting device of the present invention include GaAs, which is a 1ll-V group compound semiconductor, and A12
GaAs, 4nP...! nGaAsP,,1nG
aP% In^eP1GaAsl', GaN,
, InAsP, InAs5h, etc., n-vi group compound semiconductors Zn5e, ZnS, ZnO, Cd
PbTe, Pb5nTe, which are IV-VI group compound semiconductors such as Se and CdTe.

There are materials such as Pb5nSe and SiC, which is an rV-IV group compound semiconductor, and each material can be applied by taking advantage of its advantages.

〔Effect of the invention〕

As is clear from the above description, the junction type semiconductor light emitting device of the present invention has a lens on the top surface of the columnar protrusion or the surface of the flat plate section opposite to the side on which the columnar protrusion is formed, at a location directly below the columnar protrusion. By providing this, the pn inside the columnar protrusion
The light emitted from the junction can be diverged or focused depending on the use of the light emitting element, and the light perpendicular to the flat plate part can be effectively used, expanding the range of use of the light emitting element.

[Brief explanation of drawings]

FIGS. 1A and 1B are cross-sectional views of one embodiment of the junction type semiconductor light emitting device of the present invention, in which (a) the top surface of the columnar protrusion is formed into a convex lens shape, and (b) a concave lens. FIGS. 2(a) and 2(b) are cross-sectional views of another embodiment of the junction type semiconductor light emitting device of the present invention, in which (a) the lower surface of the flat plate portion is formed into a convex lens shape. (b) shows one formed in a concave lens shape, and FIG. 3 is a sectional view of a conventional junction type semiconductor light emitting device. (P) Two cylindrical protrusions (B) Two-hand plate part (PN l ), (PN2): pn junction (El), (E
2) : Electrode (fl) ~ (f4) : Lens (10) : Insulating film (F) : Reflective film

Claims (5)

[Claims] (1) Consisting of a flat plate part, a columnar protrusion provided on one side of the flat plate part, and an electrode provided at any location on the flat plate part and the columnar protrusion, at least within the columnar protrusion in a direction perpendicular to the flat plate part. In a junction type semiconductor light emitting device having an extending p-n junction, a lens is provided at a location directly below the columnar projection on the top surface of the columnar projection or on the surface of the flat plate portion opposite to the side on which the columnar projection is formed. Junction type semiconductor light emitting device with characteristics. (2) The junction type semiconductor light emitting device according to claim (1), wherein the lens has a concave shape to diverge light emitted from the pn junction within the columnar projection. (3) The junction type semiconductor light emitting device according to claim (1), wherein the lens has a convex shape that focuses light emitted from a pn junction within a columnar projection. (4) The junction type semiconductor light emitting device according to claim (1), wherein the lens is formed from a columnar projection or a portion of a flat plate portion. (5) The junction type semiconductor light emitting device according to claim (1), wherein the lens is formed of an organic material or an inorganic material.