JPH10261818A - Light emitting semiconductor device - Google Patents

Abstract

(57) [Summary] PROBLEM TO BE SOLVED: To provide a plurality of light emitting semiconductor devices with one chip.
, Especially three primary colors of light. A light emitting diode is provided on a light emitting surface of a light emitting diode.
Emission wavelength λ of Iode 3 _ALonger wavelength λ_BOf light 7
An emitting light emitting layer 4 is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light-emitting semiconductor device, and more particularly to a light-emitting semiconductor device capable of emitting three primary colors of light with a single chip by using a wavelength conversion material to enable full-color display. It is.

[0002]

2. Description of the Related Art A conventional light emitting diode emits light by a transition between a conduction band and a valence band by applying a forward bias to a pn junction, or a nitrogen or Zn-O pair formed in a semiconductor. The light emission due to the transition via the impurity level was used.

[0003]

However, in the conventional light emitting diode, the emission wavelength is defined by the energy corresponding to the energy gap of the semiconductor constituting the pn junction or the energy of the impurity level.
Since light of only one type of wavelength can be obtained, if a full-color display device is to be realized with light emitting diodes, light emitting diodes of multiple chips are required for one pixel,
There is a problem that a pixel becomes large or a cost per pixel becomes large.

In order to emit light at a plurality of wavelengths with one chip, a non-doped GaP layer or a nitrogen-doped GaP layer is grown on a GaP layer containing a Zn—O pair.
Although it has been proposed to form a pn junction in the aP layer to obtain red light emission and green light emission, a blue light emitting diode required for a full-color display device has a zinc blende type crystal structure.
Unlike P, since it is composed of a group III nitride semiconductor having a wurtzite crystal structure, it has been difficult to integrate a group III nitride semiconductor on GaP.

Accordingly, an object of the present invention is to emit light of a plurality of wavelengths, in particular, three primary colors of light from one chip.

[0006]

FIG. 1 is an explanatory view of the principle configuration of the present invention. Referring to FIG. 1, means for solving the problems in the present invention will be described. See FIG. 1A. (1) In the present invention, in a light emitting semiconductor device, a light emitting wavelength λ _{A of} a light emitting diode 3 is provided on a light emitting surface of the light emitting diode 3.
A light emitting layer 4 that emits light 7 having a longer wavelength λ _B than the light emitting layer 4 is provided.

As described above, the light emitting surface of the light emitting diode 3 is longer than the light emitting wavelength λ _A at the pn junction formed between the one conductivity type semiconductor layer 1 and the opposite conductivity type semiconductor layer 2 of the light emitting diode 3. By providing the light emitting layer 4 that emits light of the wavelength λ _B , that is, the photoluminescence layer (PL layer), the excitation light 6 from the light emitting diode 3 is absorbed by the light emitting layer 4 and the emission wavelength λ _{A of the} excitation light 6 Long wavelength λ different from
_B (that is, λ _A <λ _B ) can be emitted.

(2) The present invention is characterized in that, in the above (1), a semiconductor having a forbidden band width smaller than a forbidden band width of a light emitting region of the light emitting diode 3 is used as the light emitting layer 4.

As described above, by using a light emitting region of the light emitting diode 3 as the light emitting layer 4, that is, a semiconductor having a forbidden band width smaller than the forbidden band width of the active layer or the pn junction region, the light emitting layer 4 is formed on the light emitting diode 3. And can be integrated by epitaxial growth.

FIG. 1 (b) (3) According to the present invention, in a light emitting semiconductor device, a plurality of light emitting diodes 3 are provided on the same substrate, and the light emitting surface of each light emitting diode 3 emits light. Wavelength λ _A
Light emitting layers 4 and 5 which emit light 7 and 8 having longer wavelengths and different emission wavelengths λ _B and λ _C from each other are provided.

As described above, by integrating a plurality of light emitting diodes 3, a plurality of wavelengths λ can be obtained by one chip.
Lights 7 and 8 of _B and λ _C can be emitted. In particular, by providing three light-emitting layers 4 and 5 corresponding to the three primary colors of light, full-color display becomes possible.

(4) The present invention is characterized in that in (3), a semiconductor having a forbidden band width smaller than the forbidden band width of the light emitting region of the light emitting diode 3 is used as the light emitting layers 4 and 5. .

As described above, by using a semiconductor having a band gap smaller than the band gap of the light emitting region of the light emitting diode 3, that is, the active layer or the pn junction region, as the light emitting layers 4 and 5, the light emitting layers 4 and 5 are formed. It can be integrated on the light emitting diode 3 by epitaxial growth.

(5) In the present invention, according to the above (4), at least one of the light emitting layers 4 and 5 is doped with an impurity, and is different from a non-doped light emitting layer by light emission through an impurity level. It emits light 7 and 8 having different wavelengths.

As described above, by utilizing light emission via an impurity level, a plurality of light emitting layers 4 and 5 which emit light 7 and 8 having different wavelengths from one kind of semiconductor can be formed. .

(6) The present invention is characterized in that, in the above (5), the light emitting layers 4 and 5 doped with impurities are ion implantation layers.

As described above, the light emitting layers 4 and 5 which emit light 7 and 8 having different wavelengths from the non-doped light emitting layers 4 and 5 can be formed by utilizing ion implantation.
Also, the emission wavelength can be arbitrarily selected by changing the type of the impurity to be implanted.

(7) The present invention is characterized in that, in the above (4) or (5), the light emitting layers 4 and 5 are selective growth layers.

As described above, the light emitting layers 4 and 5 may be constituted by selective growth layers. In this case, a crystal growth apparatus such as MOVPE can be used without an ion implantation apparatus.
The light emitting layers 4 and 5 that emit light 7 and 8 having different wavelengths can be formed by the apparatus (metal organic chemical vapor deposition apparatus).

(8) In the present invention, in the above (4), two or more types of the semiconductor constituent elements constituting the light emitting layers 4 and 5 and the semiconductor constituent elements constituting the light emitting region of the light emitting diode 3 are used. It is characterized by having a common element.

As described above, by forming the light emitting layers 4 and 5 from semiconductors having two or more kinds of common elements with respect to the semiconductor forming the light emitting region of the light emitting diode 3,
Lattice matching can be easily achieved, and crystal growth becomes easy.

(9) The present invention is characterized in that in (5), the semiconductor forming the light emitting layers 4 and 5 and the semiconductor forming the light emitting region of the light emitting diode 3 are nitride semiconductors.

As described above, by using a nitride semiconductor, it is possible to obtain emission of light having a wavelength shorter than blue or blue, and to obtain PL light having a longer wavelength such as red or green by selecting an impurity. Therefore, full-color display using the three primary colors of light becomes possible.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIGS.
Next, a first embodiment of the present invention will be described. Referring to FIG. 2A, first, using the MOVPE method, the c-plane, that is, (000)
1) On the sapphire substrate 11 whose main surface is the surface,
0-20.0 μm, for example, 5.0 μm n-type GaN
Buffer layer 12, having a thickness of 0.1 to 1.0 μm, for example, 0.1 μm.
5 μm n-type Al _0.05Ga_0.95N barrier layer 13, thickness
0.03-0.5 μm, for example, 0.1 μm In_0.05
Ga_0.95N active layer 14, thickness 0.1 to 1.0 μm, for example
For example, 0.5 μm p-type Al_0.05Ga_0.95N barrier layer 1
5, p having a thickness of 0.1 to 5.0 μm, for example, 3.0 μm
Type GaN contact layer 16 and a thickness of 0.5 to 50.
0 μm, for example, 10.0 μm In_0.2Ga_0.8N sucking
The collecting layer 17 is sequentially grown epitaxially.

Next, a Zn doped region 20 is formed by selectively implanting Zn ions 19 into the In _0.2 Ga _0.8 N absorption layer 17 using a mask 18 made of a resist pattern.

Referring to FIG. 2B, the mask 18 is removed, and then a new mask 21 made of a resist pattern is used to form In _0.2 Ga _0.8 N.
The Hg doped region 23 is formed by selectively implanting Hg ions 22 into the absorption layer 17.

Next, after the mask 21 is removed, a new mask 24 made of a resist pattern is used to remove In _0.2 Ga _0.8 N
Mg-doped regions 26 are formed by selectively implanting Mg ions 25 into the absorption layer 17.

Next, after the mask 24 is removed, a mask 27 is provided and dry etching is performed to expose a part of the p-type GaN contact layer 16 for providing a p-side electrode. .

Referring to FIG. 4E, after removing the mask 27, a mask 28 is provided, and dry etching is performed to obtain n-type Ga.
By forming a separation groove 29 reaching the N buffer layer 12, the light emitting diode is separated into three light emitting diodes.

Referring to FIG. 4F, after removing the mask 28, the exposed surface of the p-type GaN contact layer 16 of each of the separated light emitting diodes is
By providing the side electrodes 31 to 33 and providing the n-side common electrode 30 in the n-type GaN buffer layer 12 exposed in the separation groove 29, the light emitting semiconductor device chip is completed.

The n-side common electrode 30 and the p-side electrode 31
When a forward bias is applied between the forward bias and
Ultraviolet light having a wavelength of 372 nm is generated in the In _0.05 Ga _0.95 N active layer 14 immediately below the _0.2 Ga _0.8 N absorption layer 17, and this ultraviolet light becomes the excitation light 31 and becomes the Zn-doped region 2.
0, Hg-doped region 23 and Mg-doped region emit green light, red light and blue light, respectively.

FIG. 5 is a band diagram for explaining the light emission characteristics of the light emitting semiconductor device according to the first embodiment of the present invention. FIG. 5 shows the relationship between the n-side common electrode 30 and the p-side electrode 31. when applying a forward bias to, in _0.2 Ga _0.8 N absorbent layer 17
Immediately below the In _0.05 Ga _0.95 N active layer 14, ultraviolet light having a wavelength of 372 nm is generated.
And absorbed by the Zn-doped region 20.

The excitation light 3 in the Zn-doped region 20
The electrons 35 excited in the conduction band in the electron-hole pairs generated by the absorption of No. 4 transition to the valence band after a predetermined transition time, and change to the level of the Zn ion formed in the forbidden band. transition, and the wavelength of the energy corresponding to the energy level of the E _C -Zn ions, i.e., to emit green light of 540 nm.

When a forward bias is applied between the n-side common electrode 30 and the p-side electrode 32, the Mg-doped layer 2
Ultraviolet light having a wavelength of 372 nm is generated in the In _0.05 Ga _0.95 N active layer 14 immediately below the excitation light 3.
It becomes 4 and is absorbed by the Mg-doped layer 26.

In the Mg-doped layer 26, the excitation light 34
The electrons 35 excited in the conduction band in the electron-hole pairs generated by the absorption of the electrons transition to the level of the Mg ion formed in the forbidden band after a predetermined transition time, and the E _C -Mg ion Emits blue light having a wavelength of energy corresponding to the energy of the above-mentioned level, that is, 460 nm.

When a forward bias is applied between the n-side common electrode 30 and the p-side electrode 33, the Hg doped layer 2
Ultraviolet light having a wavelength of 372 nm is generated in the In _0.05 Ga _0.95 N active layer 14 immediately below the active light 3.
It becomes 4 and is absorbed by the Hg-doped layer 23.

In the Hg-doped layer 23, the excitation light 34
The electrons 35 excited in the conduction band of the electron-hole pairs generated by the absorption of the electrons transition to the level of the Hg ion formed in the forbidden band after a predetermined transition time, and the E _C -Hg ion , And emits red light of 660 nm.

As described above, since the three primary colors of light can be independently emitted by one chip, full-color display can be achieved by appropriately adjusting the emission intensity, that is, the voltage applied to each light emitting diode. .

Therefore, one pixel of the full-color display device can be constituted by one chip, so that the screen can be made finer and the cost can be reduced.

In the first embodiment,
Although the ion implantation method is used as the impurity introduction means, the impurity may be selectively introduced by diffusion.

Next, a second embodiment of the present invention will be described with reference to FIGS. Referring to FIG. 6A, first, similarly to the first embodiment, the MOVPE method is used to form a film having a thickness of 2.0 on a c-plane, that is, a sapphire substrate 41 having a (0001) plane as a main surface. N-type GaN buffer layer 42 of 0 to 20.0 μm, for example, 5.0 μm, n-type Al of 0.1 to 1.0 μm, for example, 0.5 μm
_0.05 Ga _0.95 N barrier layer 43, thickness 0.03-0.5μ
m, for example, 0.1 μm In _0.05 Ga _0.95 N active layer 4
4. A thickness of 0.1 to 1.0 μm, for example, 0.5 μm p
Type Al _0.05 Ga _0.95 N barrier layer 45, thickness 0.1-5.
0 μm, for example, 3.0 μm p-type GaN contact layer 46 and a thickness of 0.5 to 50.0 μm, for example, 1 μm.
0.0 μm Mg-doped In _0.2 Ga _0.8 N absorption layer 47
Are sequentially epitaxially grown.

[0042] Then, a SiO ₂ mask 48 followed by patterning by depositing a SiO ₂ film, by dry etching, the SiO ₂ mask 48
Doped Mg _{0.2 In 0.8} Ga _0.8 N absorption layer 4
7 is removed to expose the p-type GaN contact layer 46.

Next, referring to FIG. 6B, the SiO ₂ mask 48 is used as a selective growth mask.
MOVPE method by growing Mg-doped an In _0.2 Ga _0.8 Zn doped an In _0.2 Ga _0. consisting ₈ N layer Zn-doped layer 49 to the removal portion of the N-absorbing layer 47.

Next, after removing the SiO ₂ mask 48, a new S
By depositing and patterning an iO ₂ film, S
An iO ₂ mask 50 is formed, and then a portion of the Mg-doped In _0.2 Ga _0.8 N absorption layer 47 is removed by dry etching using the SiO ₂ mask 50 as a mask to remove p.
The type GaN contact layer 46 is exposed.

Next, referring to FIG. 7D, the SiO ₂ mask 50 is used as a selective growth mask.
MOVPE method by growing Mg-doped an In _0.2 Ga _0.8 Hg doped layer 51 made of Hg doped In _0.2 Ga _{0. 8} N layer removal portion of the N-absorbing layer 47.

Then, although not shown, the SiO ₂ mask 50 is removed, a mask is provided, and dry etching is performed in the same manner as in the above-described steps of FIGS. 3 (d) to 4 (f). p-type G to provide p-side electrode
After exposing a part of the aN contact layer 46 and then removing the mask, a new mask is provided and dry etching is performed to thereby form the n-type GaN buffer layer 42.
The light-emitting diode is separated into three light-emitting diodes by forming a separation groove that reaches.

Finally, after removing the mask, a p-side electrode is provided on the exposed surface of the p-type GaN contact layer 46 of each of the separated light emitting diodes, and the n-type GaN buffer layer 42 exposed in the separation groove is provided. By providing the n-side common electrode, the light emitting semiconductor device chip is completed.

In the case of the second embodiment, the PL layers that emit light of different wavelengths can be formed by the MOVPE apparatus without the need for an ion implantation apparatus. Simplifies itself.

[0049] Also, the base material of the PL layer is selectively grown in this case is not necessarily the In _0.2 Ga _{0. 8} N layer, setting the composition ratio appropriately in accordance with the energy level of impurity formation using You may.

Further, without using the impurity level, the PL layer
To emit light at a wavelength corresponding to the forbidden bandwidth of
The mixed crystal ratio or composition of the L layer itself may be selected.
For light, In_0.25Ga_0.75If you grow N selectively
Good, for green emission, In_0.45Ga_0.55Select N
In order to emit red light, In
_0.95Ga_0.05N may be selectively grown.

In this case, if the lattice matching between the p-type GaN contact layer 46 and the PL layer to be selectively grown is insufficient and epitaxial growth of a thick PL layer is difficult, the growth is performed with a superlattice buffer layer interposed. Should be done.

Although the embodiments of the present invention have been described above, the present invention mainly aims at obtaining three primary colors of light with high efficiency. Therefore, at least two types of active layers and PL layers of the light emitting diode are used. Although a nitride semiconductor such as InGaN having the same constituent element is used, it is not always essential.

Further, the present invention is not limited to a light-emitting semiconductor device for full-color display using three primary colors of light.
Alternatively, a three-color light-emitting semiconductor device using two light-emitting diodes and a mixed color is also a target, and in that case, it is not necessary to use a nitride semiconductor.

The MOV in each of the above embodiments is
In the PE growth step, when growing a GaN layer, TMGa (trimethylgallium) and ammonia (NH ₃ ) are used as raw materials, and when growing an AlGaN layer, the raw materials are TMGa, TMAl (trimethylaluminum). ) And NH ₃ , and In
When growing a GaN layer, TMG is used as a raw material.
a, TMIn (trimethylindium) and NH ₃
Was used.

When an n-type layer is grown, SiH ₄ is used as an n-type impurity source. On the other hand, when a p-type layer is grown, biscyclopentadienyl magnesium is used as a p-type impurity source. Was.

The n-side common electrode 27 is made of Ti / A
A u-electrode was used, while Ni / Au electrodes were used as the p-side electrodes 28, 29, and 30.

[0057] Further, in the above embodiments, although using the In _{0. 05} Ga _0.95 N as the active layer of the light emitting diode, a mixed crystal ratio Al _x Ga in accordance with the wavelength in need
_{1-x- y} In _y N are those (0 ≦ x ≦ 1,0 ≦ y ≦ 1) may be changed within a range of, and, with it, the mixed crystal ratio of barrier layer even Al _a Ga _{1 -ab} In _b N (0 ≦ a ≦ 1,
It may be changed within the range of 0 ≦ b ≦ 1).

[0058]

According to the present invention, a plurality of different light emitting wavelength PL layers are provided on the light emitting surfaces of a plurality of light emitting diodes constituting a one chip light emitting semiconductor device. It is possible to take out light of different wavelengths, whereby the pixels constituting the full-color display can be constituted by one chip, so that the screen of the full-color display can be made finer and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a basic configuration of the present invention.

FIG. 2 is an explanatory diagram of a manufacturing process partway through the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of a manufacturing process of the first embodiment of the present invention up to the middle of FIG. 2;

FIG. 4 is an explanatory diagram of a manufacturing process of the first embodiment of the present invention after FIG. 3;

FIG. 5 is an explanatory diagram of light emission characteristics in the first embodiment of the present invention.

FIG. 6 is an explanatory diagram of a manufacturing process partway through a second embodiment of the present invention.

FIG. 7 is an explanatory diagram of a manufacturing process of the second embodiment of the present invention after FIG. 6;

[Explanation of symbols]

REFERENCE SIGNS LIST 1 one conductivity type semiconductor layer 2 reverse conductivity type semiconductor layer 3 light emitting diode 4 light emitting layer 5 light emitting layer 6 excitation light 7 light 8 light 9 separation groove 11 sapphire substrate 12 n-type GaN buffer layer 13 n-type Al _0.05 Ga _0.95 N barrier layer 14 In _0.05 Ga _0.95 N active layer 15 p-type Al _0.05 Ga _0.95 N barrier layer 16 p-type GaN contact layer 17 In _0.2 Ga _0.8 N absorption layer 18 mask 19 Zn ion 20 Zn-doped region 21 mask 22 Hg ion 23 Hg-doped region Reference Signs List 24 mask 25 Mg ion 26 Mg-doped region 27 mask 28 mask 29 separation groove 30 n-side common electrode 31 p-side electrode 32 p-side electrode 33 p-side electrode 34 excitation light 35 electrons 41 sapphire substrate 42 n-type GaN buffer layer 43 n-type al _0.05 Ga _0.95 N barrier layer 44 In _0.05 Ga _0.95 N active layer 4 p-type Al _0.05 Ga _0.95 N barrier layer 46 p-type GaN contact layer 47 Mg doped In _0.2 Ga _0.8 N absorber layer 48 SiO ₂ mask 49 Zn-doped layer 50 SiO ₂ mask 51 Hg doped layer

Claims (9)

[Claims] 1. A light-emitting semiconductor device comprising: a light-emitting layer that emits light having a wavelength longer than a light-emitting wavelength of the light-emitting diode on a light-emitting surface of the light-emitting diode. 2. The light emitting semiconductor device according to claim 1, wherein a semiconductor having a band gap smaller than a band gap of a light emitting region of said light emitting diode is used as said light emitting layer. 3. A light-emitting device in which a plurality of light-emitting diodes are provided on the same substrate, and the light-emitting surface of each of the light-emitting diodes emits light having a wavelength longer than the light-emitting wavelength of the light-emitting diodes and different light-emitting wavelengths. A light-emitting semiconductor device comprising a layer. 4. The light emitting semiconductor device according to claim 3, wherein a semiconductor having a band gap smaller than a band gap of a light emitting region of said light emitting diode is used as said light emitting layer. 5. The light emitting device according to claim 1, wherein at least one of the light emitting layers is doped with an impurity, and emits light having a wavelength different from that of the non-doped light emitting layer by light emission through the impurity level. 5. The light emitting semiconductor device according to 4. 6. The light emitting semiconductor device according to claim 5, wherein the light emitting layer doped with the impurity is an ion implantation layer. 7. The light emitting semiconductor device according to claim 4, wherein the light emitting layer is a selective growth layer. 8. The light emitting device according to claim 4, wherein two or more kinds of common elements are present in a constituent element of the semiconductor forming the light emitting layer and a constituent element of the semiconductor forming the light emitting region of the light emitting diode. Semiconductor device. 9. The light emitting semiconductor device according to claim 5, wherein the semiconductor forming the light emitting layer and the semiconductor forming the light emitting region of the light emitting diode are nitride semiconductors.