JP2002289912A - Planar light-emitting element, planar light-emitting element array, and manufacturing method of the array - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a planar light-emitting element which improves light emission efficiency by efficiently extracting the emitted light to the outside, and to provide its manufacturing method. SOLUTION: The planar light-emitting element has a light-emitting active layer 105 caught by a first conductivity-type semiconductor layer 104 and a second conductivity-type semiconductor layer 106. Moreover, this element has a structure such that a first groove structure, which reaches the second conductivity-type of semiconductor layer 106 from the first conductivity-type of semiconductor layer 104 is formed, and that a second groove structure, which reaches the first conductivity-type semiconductor layer 104 from the surface of the second conductivity-type semiconductor layer 106, is made in the direction crossing the first groove structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting diode and a surface emitting laser used in a display device, a lighting device, an optical recording device, and the like, and a method of forming these electrodes. The present invention relates to a surface light-emitting device having an electrode configuration such that light emitted from an electrode is not blocked by an electrode. Further, a surface light emitting device having a structure for efficiently guiding light emitted from the surface light emitting device to the outside, or a resonance light emitting device provided with a reflecting mirror such as a semiconductor laser, wherein generated light is blocked by the electrodes. The present invention relates to a surface light-emitting device having a structure that can be efficiently guided to a reflecting mirror without being covered. In addition, the present invention relates to a configuration in which these surface light emitting elements are integrated in an array.

[0002]

2. Description of the Related Art Conventionally, surface-emitting devices such as light-emitting diodes (LEDs) and surface-emitting semiconductor lasers (LD) have been used in display devices,
It is used as a light source for lighting or optical recording devices.

[0003] Among them, a double layer is formed in which an active layer is sandwiched between an n-type cladding layer and a p-type cladding layer, and a material is selected such that the band gap energy of the active layer is smaller than the band gap energies of the cladding layers on both sides. LEDs and LDs with a heterojunction structure have high luminous efficiency. Therefore, surface-emitting type LEDs are used for traffic lights, car tail lamps, large-area color display devices, etc., and surface-emitting type LDs are also used as array-like light sources for optical communication, writing light sources for laser beam printers, etc. I'm going.

In such an LED, an electrode provided on the surface side is formed small in order to utilize light radiated from the surface side of the LED chip, but still emits light immediately below the electrode and proceeds to the electrode side. Light is reflected by the electrodes and cannot be used effectively. Therefore, in order to eliminate such wasteful light emission and further enhance the luminous efficiency, an example in which the relative positional relationship between the light emitting portion and the electrode is adjusted inside the device to enable effective light extraction to the outside, For example,
It is described in JP-A-4-229665.

In this LED, as shown in the sectional structure of FIG. 11, an electrode 1101 on the light emitting surface side and an upper cladding layer 1106
And directly below the electrode 1101, the upper cladding layer 11
Current blocking layer 11 made of a semiconductor layer with a conductivity type different from 06
04 is provided on the cap layer 1105. With this structure, the electrode 1101 on the light emitting surface side and the electrode 1110 on the back side of the substrate 1109
The current path formed between the current diffusion layer 1103 and the current blocking layer
It reaches the active layer 1107 avoiding 1104.

That is, in this structure, light generated in a portion of the light-emitting layer, which is composed of the upper and lower cladding layers 1106 and 1108 and the active layer 1107 sandwiched between them, through which current flows, is directed upward. Since the electrode 1101 formed of a metal film does not exist directly above, there is no waste of blocking light. Therefore, the efficiency of extracting light generated in the light emitting layer is high, and the luminance can be improved.

However, in such a conventional LED, (1) a step of etching the current blocking layer 1104 is inserted in the middle, so that an additional continuous epitaxial growth step is required. (2) Although the emitted light can be prevented from being blocked by the upper electrode 1101, the light blocked by the lower electrode 1110 cannot be used. (3) When arranging a large number of such planar light emitting elements in an array, it is difficult to form electrodes. There is such a problem.

In order to solve such a problem, the present invention eliminates the need for increasing the number of epitaxial growth steps, eliminates wasteful light emission at a place where light cannot be extracted outside, and efficiently emits emitted light to the outside. It is an object of the present invention to provide a planar light emitting element with improved light emission efficiency, and a method for manufacturing the same. Further, a surface light emitting device having a structure for efficiently guiding light emitted from the surface light emitting device to the outside, or a resonance light emitting device provided with a reflecting mirror such as a semiconductor laser, wherein generated light is blocked by the electrodes. It is an object of the present invention to provide a surface light-emitting element having a structure that can be efficiently guided to a reflecting mirror without being provided, and a configuration in which these surface light-emitting elements are integrated in a ladder-like or matrix-like array.

[0009]

According to a first aspect of the present invention, there is provided a surface light emitting device having at least one layer sandwiched between a first conductive type semiconductor layer and a second conductive type semiconductor layer. A planar light-emitting element having a light-emitting active layer, wherein a first groove structure reaching from the surface of the first conductive type semiconductor layer to the second conductive type semiconductor layer is formed, It has a structure in which a second groove structure extending from the surface of the semiconductor layer of the second conductivity type to the semiconductor layer of the first conductivity type in a direction intersecting with the first groove structure is formed. .

The first groove structure and the second groove structure are viewed from above the semiconductor laminated structure so that the light emitting active layer remains only in the portion having no groove structure and the light output surface is located immediately above and below it. It is necessary to extend in the direction of intersection so as to have overlapping parts. This intersecting direction is typically an orthogonal direction, but may extend obliquely.

With such a configuration, the light generated in the active layer is emitted without any interruption by the electrodes formed directly above and below the active layer. Further, by providing a light reflecting mirror made of a metal, or a dielectric or semiconductor multilayer film on the light emitting surface, light generated in the active layer is not blocked at all by the electrodes formed as described above, Since the light reaches the reflector, an efficient cavity type light emitting element or a surface emitting laser can be constructed.

Further, when the light emitting elements are integrated in a one-dimensional or two-dimensional array, good light-emitting characteristics with no light emission crosstalk between adjacent light-emitting elements can be obtained. In particular, when a color display is formed using the structure of the light emitting element, a display with high color purity can be obtained.

Based on the above basic configuration, the following more specific modes are possible. The first groove structure and the second groove structure
Can each be composed of a pair of parallel grooves extending linearly. An embodiment described later is this example.

A substrate holding the surface light emitting element structure may be provided so as to be in contact with the surface of the first conductive type semiconductor layer and / or the surface of the second conductive type semiconductor layer. . The substrate that holds the light emitting element structure is typically a substrate that transmits light emitted from the light emitting active layer.

On the semiconductor layer surface at the bottom of each of the first groove structure and the second groove structure (the position is indicated by a broken line in FIG. 1), or on the semiconductor layer surface on the back side thereof (the position is (The position indicated by reference numeral 107).

A light having an electrode formed on at least a portion excluding a light output surface portion of a light emitting element above an ohmic electrode in contact with a semiconductor layer of the first conductivity type or the second conductivity type of the light emitting element. A transparent substrate may be attached.

A fluorescent substance can be doped or applied to the inside or the surface of the light-transmitting substrate and used for a display device or the like. Further, the above-mentioned surface light emitting elements can be easily arranged in a one-dimensional or two-dimensional array. In this case, typically, each surface light emitting element has the same structure, and the first groove structure and the second groove structure of each surface light emitting element are respectively formed in parallel.

Further, a method of manufacturing a surface-emitting light emitting device according to the present invention for solving the above-mentioned problems includes a method of manufacturing at least one layer between a semiconductor layer of a first conductivity type and a semiconductor layer of a second conductivity type. A method of manufacturing a surface-emitting light-emitting element having a light-emitting active layer, wherein a semiconductor layer of a first conductivity type, the light-emitting active layer, After sequentially laminating a light emitting element structure including a semiconductor layer of the second conductivity type, a first groove extending from the surface of the semiconductor layer of the second conductivity type to the semiconductor layer of the first conductivity type is formed by etching. Further, the semiconductor substrate having the light emitting element structure laminated thereon is attached to a first base with the semiconductor layer of the second conductivity type facing down, and the layer that can be separated is selected by selective etching. To remove After removing the semiconductor substrate, a second surface extending from the surface of the semiconductor layer of the first conductivity type to the semiconductor layer of the second conductivity type in a direction intersecting with the previously formed first groove. A surface light emitting device is manufactured by forming a groove by etching. Thereby, the surface light emitting device having the above structure can be easily manufactured.

In this method of manufacturing a surface light emitting device, after the first groove is formed by etching, a portion other than the light output surface of the semiconductor layer of the second conductivity type where the first groove is not formed is formed. Forming an electrode having an ohmic contact with the semiconductor layer of the second conductivity type, and further forming the electrode with an ohmic contact with the semiconductor layer of the second conductivity type with the semiconductor layer of the second conductivity type down; By laminating the semiconductor substrate having the light emitting element structure laminated to a first base where a first electrode having electrical contact is arranged, by selective etching,
After removing the semiconductor substrate by peeling the layer that can be peeled, in the direction intersecting with the first groove previously produced, the second conductive layer from the surface of the semiconductor layer of the first conductive type. Forming a second groove to reach the semiconductor layer of the mold by etching, the first conductive type semiconductor layer in a portion other than the light output surface of the semiconductor layer of the first conductive type where the second groove is not formed, An electrode having ohmic contact is formed, and the first conductive type semiconductor layer is bonded to an electrode having ohmic contact with a second substrate provided with a second electrode having electrical contact with the semiconductor layer of the first conductivity type. A light emitting device can be manufactured.

At least one of the first substrate and the second substrate is typically a substrate that transmits light emitted from the light emitting active layer.

The semiconductor substrate having a layer which can be separated by the selective etching includes a semiconductor substrate having a semiconductor layer having at least a composition different from that of the semiconductor substrate, a semiconductor substrate having at least a porous semiconductor layer,
The substrate may be any one of i, GaAs, and InP.

In this manufacturing method, a one-dimensional array or a two-dimensional array of surface light-emitting elements having the same structure can be manufactured using a common material and a common process.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments will be described with reference to the drawings to explain embodiments of the present invention.

(First Embodiment) FIG. 1 is a schematic perspective view showing the structure of a first embodiment of the present invention. In FIG. 1, 1
01 is a transparent substrate, 102 is an electrode provided on the transparent substrate 101,
103 is a p-type ohmic electrode, 104 is a p-type semiconductor epitaxial growth layer, 105 is an active layer, 106 is an n-type semiconductor epitaxial growth layer, and 107 is an n-type ohmic electrode.

In this structure, the electrode 1 on the transparent substrate 101
02 and the p-type ohmic contact electrode 103 are
Since it has a form not provided directly below 105, light generated in the light emitting active layer 105 is emitted downward through the transparent substrate 101 without being blocked by the electrodes. In addition, since the n-type ohmic contact electrode 107 is not provided immediately above the active layer 105, light generated in the active layer 105 is emitted upward through the n-type semiconductor epitaxial layer 106 without being blocked by the electrode. I do. Therefore, in the structure of this embodiment, light generated in the light emitting active layer 105
In addition, the light is emitted outside without being blocked by the lower electrodes 102 and 103.

With reference to FIGS. 2A to 2J, a method for fabricating the light emitting device of the first embodiment of the present invention will be described. In this embodiment, an example in which GaAlAs is used for the light-emitting layer 105 will be described.

First, a (001) n-GaAs substrate 201 having a diameter of 3 inches is prepared (FIG. 2A), and AlAs serving as an etching layer is formed thereon.
The layer 202 is epitaxially grown (FIG. 2B).

For this, after cleaning the n-GaAs substrate, the surface is etched with a sulfuric acid-based etchant to form a thin oxide film, and then set in a molecular beam epitaxy apparatus. Then, the substrate temperature is maintained at 600 ° C. while irradiating the arsenic beam, and after removing the oxide film, the solid source of gallium is heated by a K (Knudsen) cell to irradiate the gallium beam to form a GaAs layer. Epitaxial growth of 500nm.

After that, an Al beam is irradiated from a solid source of aluminum to epitaxially grow a 200 nm AlAs layer 202.

Thereafter, the gallium beam was again irradiated to epitaxially grow the n-GaAs layer 203 (FIG. 2 (c)).
After that, the n-Al _0.6 Ga _0.4 As layer 204, i (intrinsic) -Al _0.3 Ga _0.7
As layer 205 (corresponding to active layer 105 in FIG. 1), p-Al _0.6 Ga _0.4 As
The layers 206 are sequentially laminated (FIG. 2 (d)). At this time, the thickness of each of the epitaxial layers 204, 205 and 206 is 10
μm, 200 nm, and 10 μm.

Next, the wafer is taken out from the crystal growing apparatus, and a stripe having a width of 100 μm (extending in the direction perpendicular to the paper surface of FIG. 2) is patterned by photolithography. Then, the active layer 20 is etched using a Ti etching mask.
Etch until the lower part of 5 is reached. here,
The stripes were formed in the <110> direction, and were etched to a depth of 12 μm by reactive ion etching (RIE) using Cl ₂ .

Next, as shown in FIG. 2E, a p-type ohmic electrode 207 is formed on the top of the stripe.

After that, in a hydrogen atmosphere at 400 ° C. for 20 minutes.
An ohmic junction is formed by performing thermal annealing for one minute. The p-type ohmic electrode 207 is not formed on a portion serving as a light output surface, but is formed on a part of a stripe-shaped top portion (see FIG. 1). In this embodiment, 100 μm
× 1OOμm light output surface is formed, and the electrodes are 50μ on both sides.
It was formed in a size of m × 100 μm.

Thereafter, a polyimide film 208 is formed so as to fill the groove formed by the etching (FIG. 2F).

Next, the light emitting elements in the form of stripes are cut off in the stripe direction by a dicing saw or the like.
Then, an electrode 210 having a hole at the center thereof is formed on the transparent substrate 209, and the holes at the center of each other are aligned on the electrode 210 as shown in FIG. The wafer is fixed upside down with solder or the like so that the ohmic electrodes 207 of the mold overlap. In this embodiment, the size of the opening of the electrode 210 at the center is 100 μm × 100 μm.

Next, the epitaxial growth layer is separated from the substrate 201. This involves protecting the transparent substrate 209 in advance with a corrosion-resistant resist, and then etching the AlAs layer 20 as an etching layer.
Perform etching with a solution that selectively etches 2,
The epitaxial growth layer is separated from the substrate 201 (FIG.
(h)).

Further, the n-type epitaxial layer 2 of the substrate
From 04, a groove portion is formed in a direction orthogonal to the previously formed groove direction (not shown in FIG. 2 (h), but formed on the near side and the far side in the direction of the paper of the drawing). For this purpose, here
By reactive ion etching (RIE) with Cl ₂
The etching was performed until the depth reached 12 μm.

Thereafter, an n-type ohmic electrode 211 is formed so as not to block the light emitting surface with the hole at the center part interposed therebetween (FIG. 2).
(i)).

Thereafter, as shown in FIG.
The electrode 213 having a hole at the center thereof is formed on 212, and the transparent substrate 212 is turned upside down so that the holes at the center of each other are aligned and the electrode 213 and the n-type ohmic electrode 211 overlap. Fix it.

Through the above steps, a surface light emitting device is formed. A power supply 301 was connected to the electrodes 210 and 213 of the fabricated AlGaAs double heterostructure light emitting element as shown in FIG. 3 and a current was applied.
Through 9 and 212, high-luminance light emission was confirmed. The quantum efficiency of light emission with respect to the injected current was about 20% when all the light emissions were integrated.

(Second Embodiment) FIG. 4 is a schematic configuration diagram showing a second embodiment of the present invention. Here, 401 is a transparent substrate, 4
02 is an electrode having a hole in the center provided on the transparent substrate 401, 403 is a p-type ohmic electrode, 404 is a p-type semiconductor epitaxial growth layer, 405 is an active layer, 406 is an n-type semiconductor epitaxial growth layer, 407 Is an n-type ohmic electrode, 408
And 409 are reflecting mirrors formed between a pair of ohmic electrodes 403 and 407, respectively.

A method for manufacturing a light emitting device according to the second embodiment of the present invention will be described with reference to FIGS. This embodiment also shows an example in which GaAlAs is used as the light emitting layer.

In order to manufacture a planar light emitting device having such a configuration, in this embodiment, first, a GaAs substrate 501 is prepared (FIG. 5A), and a hole in the surface portion is closed thereon. Separated porous layer 50
2 is produced (FIG. 5 (b)).

This includes an n-type (10 μm) having a thickness of 450 μm.
0) A 2-inch diameter GaAs substrate 501 having an orientation is ultrasonically cleaned with isopropyl alcohol and methyl alcohol sequentially, and then In is attached to the back surface to make electrical contact. further,
This substrate 501 is anodized with an aqueous HCl solution. At this time, the current was measured while gradually increasing the applied voltage. Finally, the thickness of the porous layer 502 after anodizing for 10 minutes by passing a current of 5 mA / cm ² is 10 microns,
The porosity was 20%.

Next, the substrate is carried into the MBE apparatus,
While irradiating the arsenic beam with a solid source, the temperature of the substrate is gradually raised, and finally raised to 600 ° C., and held for 20 minutes. At this time, RHEED (Reflecti
on High Energy Electron Diffraction) pattern, the pattern gradually changed from a halo pattern to a spot pattern and streak pattern, and finally a 2 × 4 surface reconstruction was confirmed. The formation was confirmed.

Next, the GaAs / AlGa is continuously formed by the MBE method.
As double heterostructure is epitaxially grown. To do this, while the substrate temperature is maintained at 600 ° C, the gallium beam is heated by heating the solid source of gallium in the K cell while irradiating the substrate with the arsenic beam by heating the solid source of arsenic in the K cell. Irradiation is performed to epitaxially grow the n-GaAs layer 503 (FIG. 5C).

Thereafter, the n-Al _0.6 Ga _0.4 As layer 504, i-Al _0.3
Ga _0.7 As layer 505 and p-Al _0.6 Ga _0.4 As layer 506 are sequentially laminated
(FIG. 5 (d)). At this time, the thicknesses of the respective epitaxial layers were 5 μm, 200 nm, and 5 μm, respectively.

Next, the wafer is taken out of the crystal growing apparatus, and a stripe having a width of 100 μm is patterned by photolithography. Thereafter, etching is performed using an etching mask made of Ti until the wafer reaches a lower portion of the active layer 505 (FIG. 5 (e)). Here, the stripe is <11
0> direction, and was etched to a depth of 6 μm by reactive ion etching (RIE) using Cl ₂ .

Next, a pair of p-type ohmic electrodes 507 sandwiching the central hole is formed on the top of the stripe (FIG. 5E). Then, at 400 ° C. in a hydrogen atmosphere for 20 minutes.
An ohmic junction is formed by performing thermal annealing for one minute. As described above, the p-type ohmic electrode 507 is not formed on the central portion serving as the light output surface, but is formed on a part of the top portion formed in a stripe shape.

Further, the light exit surface of the hole at the center is provided with Si
A multilayer film 514 made of O ₂ / TiO ₂ is formed to create a structure in which light emitted from the active layer 505 is efficiently reflected. In the present embodiment, a light output surface of 100 μm × 100 μm was formed, and the electrode portions 507 were formed on both sides in a size of 50 μm × 100 μm.

After that, an insulating film 508 is formed so as to fill the groove formed by the etching.
(f)). In this embodiment, polyimide is used for the insulating film 508.

Next, each stripe-shaped light emitting element is cut off in the stripe direction by a dicing saw or the like. After that, as shown in FIG. 5 (g), an electrode 510 having a hole at the center is formed on the transparent substrate 509, and a p-type ohmic electrode 507 is superimposed on the electrode 510 by soldering or the like. The wafer is fixed upside down. In this embodiment, the size of the opening at the center of the electrode 510 is 100 μm × 100 μm.

Next, the epitaxial growth layer is separated from the substrate 501. To this end, after protecting the transparent substrate 509 with a corrosion-resistant resist in advance, etching is performed with a solution for selectively etching the porous layer 502 serving as an etching layer, and the epitaxial growth layer is peeled from the substrate 501 (FIG. 5).
(h)). In this example, a sulfuric acid / hydrogen peroxide-based etchant was used as an etchant at this time.

Further, a groove is formed from the n-type epitaxial layer of the substrate in a direction perpendicular to the direction of the groove previously formed. For this reason, here, etching was performed by reactive ion etching (RIE) using Cl ₂ until the depth reached 6 μm.

Thereafter, an n-type ohmic electrode 511 is formed so as not to block the light emitting surface (FIG. 5 (i)). Further, a light reflecting mirror 515 is formed on the light emitting surface. Here, Ti0 ₂ /
A dielectric multilayer film consisting of Si0 ₂ was formed by electron beam evaporation method. The light reflecting mirror 515 may be formed of a thin metal (such as Au) that partially transmits light. Further, a multilayer film having a semiconductor heterostructure may be formed.

Thereafter, as shown in FIG.
An electrode 513 having a hole at the center is formed on 512, and the hole at the center and the light reflecting mirror 515 are aligned and this electrode 513 is formed.
The transparent substrate 512 is placed so that the n-type ohmic electrode 511 overlaps.
Is fixed upside down.

The light emitting device is formed by the steps described above. As shown in FIG. 3, a power supply 301 was connected to the electrodes of the fabricated AlGaAs double heterostructure light emitting element, and when a current was passed, the reflecting mirrors 514 and 515 were formed. Good light was emitted. The quantum efficiency of the light emission with respect to the injected current was about 20% in a state where the light emission emitted vertically was integrated.

In the present embodiment, the reflecting mirrors 514 and 515 are also made to have a structure closer to the active layer 505 by making a contrivance such as manufacturing them by epitaxial growth.
A surface-emitting type semiconductor laser in which light loss in the optical resonator formed between 4, 515 can be reduced.

(Third Embodiment) Next, a third embodiment of the present invention will be described. This embodiment is a light-emitting element having a structure in which light emitted from a light-emitting active layer made of a nitride-based compound semiconductor containing at least nitrogen is emitted outside without being blocked by an electrode.

In order to manufacture a surface light emitting device having such a structure, first, a porous layer having a surface portion whose holes are closed is formed on a GaAs substrate. This fabrication was performed in the present embodiment in the same manner as in the second embodiment.

Next, an NH ₃ source was continuously introduced into the MBE apparatus carrying the substrate to nitride the surface of the porous GaAs layer whose surface layer was closed. Irradiation grows the n-GaN layer to 10 μm. Then, n-Al _0.2 Ga
_0.8 N layer, n-In _0.25 Ga _0.75 N active layer, p-Al _0.2 Ga _0.8 N layer, p
-Grow the GaN layer to 10 μm.

Thereafter, etching is further performed until reaching the lower portion of the active layer, here, to a depth of 12 μm. Here, reactive ion etching (RIE) with Cl ₂
Etching was performed.

Next, a p-type ohmic electrode 804 is formed on the top of the stripe. Here, Ni is used as the electrode.
(1000Å) / Au (3000Å) was used. Thereafter, by performing thermal annealing at 400 ° C. for 20 minutes in a hydrogen atmosphere,
An ohmic junction is formed. The p-type ohmic electrode is not formed on a portion serving as a light output surface, but is formed on a part of a stripe-shaped top portion.

Thereafter, an insulator film is formed so as to fill the groove formed by the etching. Also in this example, a polyimide film was used.

Next, an electrode having a hole is formed on a transparent glass substrate, and the wafer is fixed upside down so that the p-type ohmic electrode overlaps the electrode.

Next, the epitaxial growth layer is separated from the substrate. To this end, first, the substrate is thinned by polishing using a polishing liquid, and then the GaAs substrate portion and the porous portion are all removed with a sulfuric acid-based etching solution, and Ga is removed.
Etching is performed until only the N light emitting diode portion remains.

Further, a groove is formed from the n-type epitaxial layer of the substrate in a direction orthogonal to the direction of the groove previously formed. For this reason, here, etching was performed by reactive ion etching (RIE) using Cl ₂ until the depth reached 12 μm.

Next, an n-type ohmic electrode made of Ti (500 °) / Al (1 μm) / Au is manufactured. Finally, an electrode with a hole is formed on another transparent glass substrate, and the transparent glass substrate is turned upside down so that the electrode with the hole overlaps the n-type ohmic electrode. Fix using

By the steps described above, a light emitting element is formed. When a power supply was connected to the electrode of the manufactured light emitting element having the InGaN double hetero structure and a current was passed, high-luminance light emission was confirmed through the glass surface and the semiconductor layer.
The quantum efficiency of light emission with respect to the injected current was about 20% when all the light emissions were integrated.

In this embodiment, the active layer
Although an example using InGaN has been described, the present invention is not limited to this, and a structure using a general nitride semiconductor represented by Al _x Ga _y In _1-x-y N as an active layer, an Al _x Ga _y In _1−x−y As _z N _1−z or A
_{l x Ga y In 1-x} -y P z N 1-z a nitride semiconductor such as may be the structure as an active layer.

(Fourth Embodiment) FIG. 6 is a block diagram showing a fourth embodiment of the present invention. This embodiment is the first, second, or
In this example, the light emitting devices of the third embodiment are integrated in a one-dimensional array.

The device can be manufactured by the second, third, or third method.
Since this embodiment is the same as the embodiment, the description is omitted here. However, in order to form an array, the electrode 6 having the structure shown in FIGS.
The difference is that translucent substrates 601 and 609 in which 02 and 608 are patterned are provided. In FIG. 6, 603 is
A p-type ohmic electrode, 604 is a p-type semiconductor epitaxial growth layer, 605 is an active layer, 606 is an n-type semiconductor epitaxial growth layer, and 607 is an n-type ohmic electrode.

This light-emitting element array was connected as shown in FIG. 7, and when potentials were applied independently by the power supplies Vd1 to Vdn, it was possible to independently control the light emission amount of each light-emitting element. Such a light-emitting element array can be used as a writing light source of an LED printer or as a contact-type reading illumination means such as a facsimile or a scanner.

(Fifth Embodiment) FIG. 8 is a block diagram showing a fifth embodiment of the present invention. In this embodiment, a simple matrix of XY is formed using the light emitting element of the present invention.

In this figure, 801 is a transparent substrate, 802 is an electrode provided on the transparent substrate 801, 803 is a p-type ohmic electrode, 804 is a p-type semiconductor epitaxial growth layer, 805 is an active layer, and 806 is an n-type. Semiconductor epitaxial growth layer, 807
Denotes an n-type ohmic electrode, 809 denotes a transparent substrate, and 808 denotes an electrode provided on the transparent substrate 809.

In order to manufacture a surface light emitting device having such a structure, a porous layer whose surface layer is closed is formed on a GaAs substrate. This fabrication was performed in the present embodiment in the same manner as in the second embodiment.

Next, an NH ₃ source was continuously introduced into the MBE apparatus into which the substrate was carried, and the surface of the porous GaAs layer whose surface layer was closed was nitrided. Irradiation grows the n-GaN layer to 10 μm. Then, n-Al _0.2 Ga
_0.8 N layer, n-In _0.25 Ga _0.75 N active layer 805, p-Al _0.2 Ga _0.8 N
A layer and a p-GaN layer are grown by 10 μm.

Thereafter, the etching is further performed until reaching the lower portion of the active layer, here, to a depth of 12 μm. Here, reactive ion etching (RIE) with Cl ₂
Etching was performed.

Next, a p-type ohmic electrode 803 is formed on the top of the stripe. Here, Ni is used as the electrode.
(1000Å) / Au (3000Å) was used. Thereafter, by performing thermal annealing at 400 ° C. for 20 minutes in a hydrogen atmosphere,
An ohmic junction is formed. This p-type ohmic electrode 8
03 is not formed on a portion serving as a light output surface, but is formed on a part of a top portion formed in a stripe shape.

Thereafter, an insulator film (not shown) is formed so as to fill the groove formed by the etching. Also in this example, a polyimide film was used.

Next, an array-shaped electrode 802 having a hole is formed on a transparent glass substrate 801, and the wafer is fixed upside down so that a p-type ohmic electrode 803 is overlapped thereon.

Next, the epitaxial growth layer is separated from the substrate. To do this, first, the substrate is thinned by polishing using a polishing liquid, and then the GaAs substrate portion and the porous portion are all removed using a sulfuric acid-based etching solution.
Until only the light emitting diode part of GaN remains
Perform etching.

Further, a groove is formed from the n-type epitaxial layer of the substrate in a direction orthogonal to the direction of the groove previously formed. For this reason, here, etching was performed by reactive ion etching (RIE) using Cl ₂ until the depth reached 12 μm.

Next, an ohmic electrode 807 made of Ti (500 °) / Al (1 μm) / Au is manufactured. Finally, an array-shaped electrode 808 having a hole is formed on the transparent glass substrate 809, and the n-type ohmic electrode 807 is fixed thereon using solder or the like so as to overlap.

Through the steps described above, light emitting elements arranged in a matrix are formed. InGaN fabricated
When a power supply was connected to the electrodes 802 and 808 of the light emitting element having a double hetero structure as shown in FIG. 9 and a current was applied, high-luminance light emission was confirmed through the glass surface. The quantum efficiency of light emission with respect to the injected current was about 20% when all the light emissions were integrated.

At this time, the operating voltage at the time of light output is reduced by sufficiently reducing the contact resistance of each ohmic electrode.
When Vf is used, the current flowing at the voltage of Vf / 2 can be made 1/1000 or less of the current flowing at the time of optical output. This makes it possible to control light emission and non-light emission by driving each element individually in a simple matrix configuration.

(Sixth Embodiment) In a sixth embodiment according to the present invention, a laser or LED that emits blue to ultraviolet light (420 to 380 nm) using a GaN-based material is attached to a glass substrate as in the above embodiment. This is an example of a two-dimensional array. At this time,
A glass substrate is coated with a phosphor that emits R, G, and B fluorescent light for each pixel, so that the glass substrate is applied as a full-color display element by light excitation from blue to ultraviolet light.

As the pixels, the pixel diameter is 25 μmφ, and the interval is 7
Since it can be realized at about 5 μm and the area can be very large in principle, a thin large-screen full-color display element can be provided. Since a low threshold laser or LED is used as a light source,
Advantageously, display with low power consumption and high luminance can be performed, and high voltage and vacuum are not required.

The method for manufacturing this light emitting element is the same as that of the fifth embodiment. FIG. 10 shows an example of a full-color display element manufactured using the surface emitting semiconductor device of the sixth embodiment.
As shown in FIG. 10, a plurality of GaN-based light emitting elements 1002 having a unit of about 60 mm are arranged on a glass plate 1001 for a display element. A square portion in the light emitting element 1002 corresponds to one pixel.

The number of GaN light-emitting elements (one in each square) drawn in FIG. 10 is not limited to the number shown in the figure, but is about 60 inches if the glass plate area is increased and many are integrated. It can also handle large screens.

In this embodiment, the arrangement of RGB is triangular, and the vertexes and bases are arranged alternately. But,
The arrangement of RGB is not limited to that of FIG. 10, and the ratio of the number of pixels may be controlled according to the luminance of each color.

[0092]

As described above, in the present invention, a substrate which can be separated by selective etching is used. After epitaxial crystal growth, a groove extending from the upper surface of this structure (epitaxial growth surface) to below the active layer is formed by etching, then the epitaxial growth surface is turned down, and only this epitaxial growth layer is transferred to another substrate. A light emitting device having a structure in which a groove is formed to reach below the active layer in a direction intersecting with the previously prepared groove, and an electrode is formed on each groove or on the epitaxial growth surface on the back side of the groove. Produced.

With such a configuration, light generated in the active layer is emitted without any interruption by the formed electrodes. Further, by providing a light reflecting mirror made of a metal, dielectric or semiconductor multilayer film on the light emitting surface, light generated in the active layer reaches the reflecting mirror without being completely blocked by the formed electrodes. As a result, an efficient resonator type light emitting element or a surface emitting type laser can be constructed.

By arranging the light-emitting elements in a ladder shape, an array of one-dimensionally arranged light-emitting elements can be formed, in which each light-emitting element can be driven independently. Efficient light emission without blocking light is obtained.

Further, by arranging the light emitting elements in a simple matrix configuration, an array of two-dimensionally arranged light emitting elements capable of independently driving each light emitting element can be formed. Efficient light emission can be obtained without light being shielded by each electrode.

Further, when the light emitting devices are integrated in a one-dimensional or two-dimensional array, good light emitting characteristics without light emission crosstalk can be obtained between adjacent light emitting devices.
When a color display is formed using the structure of the light-emitting element, a display with high color purity can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating a structure of a light emitting device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a step of manufacturing the light emitting device according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating a driving method of the light emitting device according to the first embodiment of the present invention.

FIG. 4 is a schematic configuration diagram illustrating a structure of a light emitting device according to a second embodiment of the present invention.

FIG. 5 is a diagram illustrating a step of manufacturing a light-emitting element according to a second example of the present invention.

FIG. 6 is a schematic configuration diagram illustrating a structure of a ladder-shaped light emitting element array according to a fourth embodiment of the present invention.

FIG. 7 is a schematic configuration diagram illustrating a driving method of a ladder-shaped light emitting element array according to a fourth embodiment of the present invention.

FIG. 8 is a schematic configuration diagram illustrating a structure of a matrix light emitting element array according to a fifth embodiment of the present invention.

FIG. 9 is a schematic configuration diagram illustrating a driving method of a matrix light emitting element array according to a fifth embodiment of the present invention.

FIG. 10 is a schematic configuration diagram illustrating a display using a matrix light-emitting element array according to a fifth embodiment of the present invention.

FIG. 11 is a schematic configuration diagram illustrating a structure of a conventional surface-emitting light emitting device.

[Explanation of symbols]

101,209,212,401,509,512,601,609,801,809: Substrate 102,402,602,608,802,808: Electrode provided on the substrate 103,207403,507,603,803: P-type ohmic electrode 104,404,604,804: P-type semiconductor epitaxial growth layer 105,405,605,805: Active layer 106,406,606,806: N-type semiconductor epitaxial layer 107, N-type 407, N-type semiconductor 407, N-type semiconductor 807 201,501: Semiconductor substrate 202,502: Etched layer 203,503: n-GaAs semiconductor layer 204,504: n-Al _0.6 Ga _0.4 As layer 205,505: i-Al _0.3 Ga _0.7 As layer 206,506: p-Al _0.6 Ga _0.4 As layer 208,508: Insulating film 210,213,510,513 : Electrode 301: Power supply 408, 409, 514, 515: Light reflecting mirror 1001: Glass substrate 1002: Light emitting element array 1101: Upper electrode 1102: Contact layer 1103: Current diffusion layer 1104: Current blocking layer 1105: Cap layer 1106: Upper cladding layer 1107: Active layer 1108: Lower cladding layer 1109: Substrate 1110: Lower electrode

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Taku Ezaki 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 5F041 AA03 CA04 CA12 CA34 CA35 CA36 CA40 CA46 CA66 CA74 CA76 CA77 CA82 CA92 CA93 CB01 CB02 CB25 EE25 FF01 FF06 FF11 5F073 AB02 AB17 BA02 BA06 BA09 CA04 CB02 DA06 DA25 DA35

Claims (26)

[Claims] 1. A planar light emitting device having at least one light emitting active layer sandwiched between a semiconductor layer of a first conductivity type and a semiconductor layer of a second conductivity type, wherein: A first groove structure reaching from the surface of the semiconductor layer to the semiconductor layer of the second conductivity type is formed, and further, from the surface of the semiconductor layer of the second conductivity type in a direction intersecting with the first groove structure. A surface light emitting device having a structure in which a second groove structure reaching the semiconductor layer of the first conductivity type is formed. 2. The surface light emitting device according to claim 1, wherein said second groove structure is formed in a direction orthogonal to said first groove structure. 3. The surface light emitting device according to claim 1, wherein each of the first groove structure and the second groove structure comprises a pair of parallel grooves extending linearly. . 4. A substrate holding the planar light emitting element structure is provided so as to be in contact with the surface of the first conductive semiconductor layer and / or the surface of the second conductive semiconductor layer. The surface light-emitting device according to claim 1, wherein: 5. The surface light emitting device according to claim 4, wherein the substrate holding the light emitting device structure is a substrate transparent to light emitted from the light emitting active layer. 6. An ohmic electrode is formed on the semiconductor layer surface at the bottom of each of the first groove structure and the second groove structure or on the semiconductor layer surface on the back side thereof. 5. The surface light emitting device according to any one of 5. 7. A light reflecting mirror made of a dielectric multilayer film, a semiconductor multilayer film, or a metal is formed on the light output surface of the light emitting element immediately above and below the light emitting active layer. The surface light-emitting device according to claim 1. 8. A light-transmitting substrate having an electrode formed on at least a portion of the ohmic electrode in contact with a semiconductor layer surface of the first conductivity type of the light emitting element except for a light output surface of the light emitting element. The surface light emitting device according to claim 6, wherein is bonded. 9. A light-transmitting substrate having an electrode formed on at least a portion of the ohmic electrode in contact with a semiconductor layer surface of the second conductivity type of the light emitting element except for a light output surface of the light emitting element. The surface light emitting device according to claim 6, wherein is bonded. 10. The method according to claim 10, wherein the light-transmitting substrate is provided inside or on the surface thereof.
10. The surface light emitting device according to claim 5, wherein a phosphor is doped or coated. 11. A surface light emitting element array, wherein the surface light emitting elements according to claim 1 are arranged in a one-dimensional array. 12. A surface light-emitting element array, wherein the surface light-emitting elements according to claim 1 are arranged in a two-dimensional array. 13. The surface light-emitting device has the same structure, and the first groove structure and the second groove structure of each surface light-emitting device are:
13. The planar light emitting element array according to claim 11, wherein each is formed in parallel. 14. A display comprising the surface light-emitting element array according to claim 12. 15. A method for manufacturing a surface light emitting device having at least one light emitting active layer sandwiched between a semiconductor layer of a first conductivity type and a semiconductor layer of a second conductivity type. On a semiconductor substrate having a layer that can be, the first conductivity type semiconductor layer, the light emitting active layer,
After sequentially laminating the light emitting element structures including the second conductivity type semiconductor layer, etching the first groove from the surface of the second conductivity type semiconductor layer to the first conductivity type semiconductor layer by etching Forming, further bonding the semiconductor substrate on which the light emitting element structure is laminated to the first base with the semiconductor layer of the second conductivity type down, and the layer capable of being separated by selective etching After the semiconductor substrate is removed by selectively removing the semiconductor layer of the second conductivity type from the surface of the semiconductor layer of the first conductivity type in a direction intersecting with the previously formed first groove. A method for manufacturing a surface light-emitting device, comprising: manufacturing a surface light-emitting device by forming a second groove that reaches the surface by etching. 16. The method according to claim 15, wherein the second groove is formed in a direction orthogonal to the first groove. 17. The manufacturing method according to claim 15, wherein the first groove and the second groove each comprise a pair of parallel grooves extending linearly. Method. 18. The planar light emitting device according to claim 15, wherein the first substrate is a substrate that transmits light emitted from the light emitting active layer. Device manufacturing method. 19. After forming the first groove by etching, a second conductive type semiconductor layer is formed on a portion other than the light output surface of the second conductive type semiconductor layer where the first groove is not formed. Forming an electrode having an ohmic contact with the second conductive type semiconductor layer, and having an electrical contact with the electrode having an ohmic contact with the second conductive type semiconductor layer. After bonding the semiconductor substrate on which the light emitting element structure is laminated to the first base on which the electrodes are arranged, and by selectively etching, the layer that can be separated is removed and the semiconductor substrate is removed. The first made in
In the direction intersecting the grooves, a second groove is formed by etching from the surface of the semiconductor layer of the first conductivity type to the semiconductor layer of the second conductivity type, wherein the second groove is not formed. An electrode having ohmic contact with the first conductive type semiconductor layer is formed in a portion other than the light output surface of the first conductive type semiconductor layer, and an electrode having ohmic contact with the first conductive type semiconductor layer. The method for manufacturing a surface light emitting device according to any one of claims 15 to 17, wherein the surface light emitting device is manufactured by bonding a second substrate on which a second electrode having electrical contact is arranged. . 20. The planar light emitting device according to claim 19, wherein at least one of said first base and said second base is a base which is transparent to light emitted from said light emitting active layer. Device manufacturing method. 21. A light reflecting mirror made of a dielectric multilayer film, a semiconductor multilayer film, or a metal is formed on the light output surface of the light emitting element immediately above and below the light emitting active layer. Item 21. The method for manufacturing a surface light-emitting device according to any one of Items 15 to 20. 22. The semiconductor substrate according to claim 15, wherein the semiconductor substrate having a layer which can be separated by the selective etching is a semiconductor substrate having a semiconductor layer having at least a composition different from that of the semiconductor substrate. 13. A method for manufacturing a surface light emitting device according to 23. The surface according to claim 15, wherein the semiconductor substrate having a layer which can be separated by the selective etching is a semiconductor substrate having at least a porous semiconductor layer. Method for manufacturing a light emitting device. 24. The semiconductor device according to claim 15, wherein the semiconductor substrate having a layer which can be separated by the selective etching is any one of Si, GaAs and InP.
2. The method for manufacturing a surface light emitting device according to claim 1. 25. The planar light emitting device according to claim 15, wherein a one-dimensional array of the planar light emitting device having the same structure is manufactured by a common process using a common material. Production method. 26. The planar light emitting device according to claim 15, wherein a two-dimensional array of surface light emitting devices having the same structure is manufactured by a common process using a common material. Production method.