JPH04133478A - Double hetero-junction type semiconductor light emitting element - Google Patents

Abstract

PURPOSE:To enable a semiconductor light emitting element to emit visible rays of green to blue light short in wavelength by a method wherein a semiconductor crystal substrate is formed of ZnTe, a first, a second, and a third semiconductor crystal layer are formed of MgxZn1-xTe, and a figure of X in the composition of the second semiconductor crystal layer is specified. CONSTITUTION:In a double hetero-junction type semiconductor light emitting element, a semiconductor crystal substrate 1 is formed of ZnTe. A semiconductor laminated body 5 composed of a first, a second, and a third semiconductor crystal layer, 2, 3, and 4, is formed of MgxZn1-xTe (0<x<1). At this point, X in the composition MgxZn1-xTe of the second semiconductor crystal layer 3 serving as an active layer is set smaller than those of the first and the third semiconductor layer, 2 and 4, which serve as clad layers.

Description

[Detailed description of the invention] [Industrial application field]

TECHNICAL FIELD The present invention relates to a double heterojunction semiconductor light emitting device that can emit light having a visible short wavelength.

[Conventional technology]

Conventionally, a first semiconductor crystal substrate having a first conductivity type is formed on a semiconductor crystal substrate having a first conductivity type.
A first semiconductor crystal layer as a first cladding layer having a conductivity type of a second semiconductor crystal layer serving as an active layer that is not introduced at a high concentration or is introduced only at a sufficiently low concentration and has a narrower energy band gap than the first semiconductor crystal layer; , and a third semiconductor crystal layer serving as a second cladding layer having a second conductivity type and having a wider energy band gap than the second semiconductor crystal layer are laminated in this order. A first electrode layer is ohmically applied on the surface of the semiconductor crystal substrate opposite to the semiconductor layered body, and a first electrode layer is ohmically applied on the surface of the semiconductor crystal substrate opposite to the semiconductor layered body. A double heterojunction semiconductor light emitting device in which two electrode layers are ohmic has been proposed. According to the conventional double-heterojunction semiconductor light emitting device having such a configuration, if a required power source is connected with the required polarity between the first and second electrode layers, the second electrode layer can be used as the active layer of the semiconductor stack. A current is injected into the second semiconductor crystal layer, whereby the second semiconductor crystal layer as an active layer emits light having a wavelength corresponding to its energy band gap, and the light is transmitted to the second semiconductor crystal layer as an active layer. The light propagates within the second semiconductor crystal layer while being confined by the first and third semiconductor crystal layers as the first and second cladding layers, and is emitted to the outside from the end face of the second semiconductor crystal layer as the active layer. Ru. Further, according to the conventional double heterojunction semiconductor light emitting device having the above-described configuration, when the above-mentioned light emission is obtained, the light emitted from the second semiconductor crystal layer as the active layer as described above is Based on the current that is confined by the first and third semiconductor crystal layers as the first and second cladding layers and injected into the second semiconductor crystal layer as the active layer, the second semiconductor crystal layer as the active layer Since carriers in the semiconductor crystal layer are also confined by the first and third semiconductor crystal layers serving as the first and second cladding layers, the above-mentioned light emission can be obtained with high efficiency.

[Problem to be solved by the invention]

In the conventional double-heterojunction type semiconductor light-emitting device having the above-mentioned configuration, it is possible to obtain light emission as described above. In a junction type semiconductor light emitting device, a semiconductor material having an energy band gap capable of emitting light having a visible short wavelength, such as Zn5e or GaN, is known as a semiconductor material constituting a second semiconductor crystal layer as an active layer. Therefore, even if the second semiconductor crystal layer as an active layer is made of such a semiconductor material, in that case, the first and third semiconductor crystal layers, together with the first semiconductor crystal layer, may be combined with the semiconductor crystal substrate. It satisfies the following: lattice matching, and the first semiconductor crystal layer serving as the first cladding layer and the third semiconductor crystal layer serving as the second cladding layer exhibiting a relatively low resistivity. Since a semiconductor crystal substrate capable of forming a semiconductor crystal and a semiconductor material constituting the first and third semiconductor crystal layers have not been found, this method has hardly been realized. Therefore, it is an object of the present invention to propose a novel double heterojunction type semiconductor light emitting device that can emit green to blue light having a visible short wavelength.

[Means to solve the WR problem]

The double heterojunction type semiconductor light emitting device according to the present invention is similar to the conventionally proposed double heterojunction type semiconductor light emitting device. A first semiconductor crystal layer as a first cladding layer having an impurity that provides a first conductivity type or an impurity that provides a second conductivity type opposite to the first conductivity type is intentionally introduced. a second semiconductor crystal layer serving as an active layer, which is not introduced or is introduced only at a sufficiently low concentration and has a narrower energy band gap than the first semiconductor crystal layer; a third semiconductor crystal layer as a second cladding layer having a conductivity type and a wider energy band gap than the second semiconductor crystal layer, and a semiconductor stacked body having a structure in which these layers are stacked in this order is formed, and (1) a first layer is formed on the surface of the semiconductor crystal substrate opposite to the semiconductor stacked body side.
The second electrode layer is ohmically applied, and (2) a second electrode layer is ohmically applied on the surface of the semiconductor laminate opposite to the semiconductor crystal substrate. However, in the double heterojunction semiconductor light emitting device according to the present invention having such a configuration, (1) the semiconductor crystal substrate is Z
(1) The first, second and third semiconductor crystal layers are all made of tvlZnTe (where 0〈x〈
x 1-x 1), () However, Mg of the second semiconductor crystal layer
X in ZnTe has a smaller value than X in McxZnTxl-e of the x1-x1 and third semiconductor crystal layers.

[Action/effect]

The double heterojunction type semiconductor light emitting device according to the present invention can be applied to the above-mentioned semiconductor light emitting device as long as it does not matter what kind of semiconductor material the semiconductor crystal substrate and the first, second and third semiconductor crystal layers are made of. It has a configuration similar to that of a conventional double heterojunction semiconductor light emitting device. Therefore, in the case of the double heterojunction semiconductor light emitting device according to the present invention, as in the case of the conventional double heterojunction semiconductor light emitting device described above, the required power supply is applied between the first and second electrode layers. If the polarity is connected, a current is injected into the second semiconductor crystal layer serving as the active layer of the semiconductor stack, which causes the second semiconductor crystal layer serving as the active layer to emit light with a wavelength corresponding to its energy band gap. is obtained, and the light propagates within the second semiconductor crystal layer as the active layer while being confined by the first and third semiconductor crystal layers as the first and second cladding layers. The light is emitted to the outside from the end face of the second semiconductor crystal layer. Further, according to the double heterojunction type semiconductor light emitting device according to the present invention, when the above-mentioned light emission is obtained, as in the case of the conventional double heterojunction type semiconductor light emitting device described above, as described above, the active layer is Light emitted from the second semiconductor crystal layer is confined by the first and third semiconductor crystal layers as the first and second cladding layers, and is injected into the second semiconductor crystal layer as the active layer. The carriers in the second semiconductor crystal layer as the active layer due to the current are also confined by the first and third semiconductor crystal layers as the first and second cladding layers, so that the above-mentioned light emission is prevented. can be obtained with high efficiency. However, in the case of the double heterojunction semiconductor light emitting device according to the present invention, the second semiconductor crystal layer as the active layer,
The first and third semiconductor crystal layers as the first and second cladding layers are both MgX Zn1-x TeT"
Then, MqZnTe linearly changes as the value of X increases from about 2.3 eV when the X 1-x value of X is O for its X(7) value. Since it has an energy band gap close to a large value (for example, a value of about 3.0eV when It has an energy band gap that allows it to emit light at a certain wavelength. Moreover, MQZnT of the second semiconductor crystal layer as an active layer
Since X in e has a value x1-x smaller than that in MgZnTe of the first and third semiconductor crystal layers as the first and x1-x2 cladding layers, the first and The first and third semiconductor crystal layers serving as the second ground layer have a wider energy band gap than the second semiconductor crystal layer serving as the active layer. Furthermore, since ZnTe of the semiconductor crystal substrate is a semiconductor material when x in Mg Zn1-xx Te of the first, second and third semiconductor crystal layers is O, The semiconductor crystal layer of No. 3 and the semiconductor crystal substrate have substantially equal lattice constants sufficient to lattice match each other. In addition, since the first semiconductor crystal layer as the first cladding layer is made of MgZnTe, it is possible to introduce impurities giving the first conductivity type at a relatively high concentration. , the first semiconductor crystal layer serving as the first cladding layer can have a relatively low resistivity. Furthermore, the third semiconductor crystal layer as the second cladding layer is made of vq Zn1-xTe, similar to the case of the first semiconductor crystal layer as the first cladding layer, so that it has the first conductivity type. It is possible to introduce an impurity at a relatively high concentration to give the same, and therefore, the third semiconductor crystal layer serving as the second cladding layer can have a relatively low resistivity. From the above, according to the double heterojunction semiconductor light emitting device according to the present invention, the first and third semiconductor crystal layers as the first and second cladding layers are the same as the first and third semiconductor crystal layers as the active layer.
The first semiconductor crystal layer as the first cladding layer and the third semiconductor crystal layer as the second cladding layer both have a relatively low ratio. It is possible to obtain light emission having a visible short wavelength consisting of green light or blue light while sufficiently satisfying the requirements of resistance.

Embodiment 1 Next, a first embodiment of the double heterojunction semiconductor light emitting device according to the present invention will be described with reference to FIG. The double heterojunction type semiconductor light emitting device according to the present invention shown in FIG. 1 has a first conductivity type, e.g.
A first semiconductor crystal layer 2 as a first cladding layer having p-type as a first conductivity type, and an impurity or A second semiconductor crystal layer 3 as an active layer in which none of the impurities that give n-type conductivity as the second conductivity type are intentionally introduced, or even if they are introduced, they are introduced only at a sufficiently low concentration; , a second semiconductor crystal layer 4 as a second cladding layer having n-type as the second conductivity type.
A semiconductor laminate 5 is formed in which these are stacked in that order. Further, as in the case of the conventional double heterojunction type semiconductor light emitting device described above, the semiconductor stack 5 of the semiconductor crystal substrate 1 is
A first electrode layer 6 is ohmically applied on the surface opposite to the semiconductor crystal substrate 1 side, and a second electrode layer 7 is ohmically applied on the surface of the semiconductor laminate 5 opposite to the semiconductor crystal substrate 1 side. It is attached. However, in the double heterojunction semiconductor light emitting device according to the present invention shown in FIG. 1, the semiconductor crystal substrate 1 is made of ZnTe.
It becomes. Furthermore, the first, second and third semiconductor crystal layers 2.3 and 4 constituting the semiconductor stack 5 are all made of MQX Z.
n1-x Ter. However, in this case, X in the MQZnTe of the first and third semiconductor crystals H2 and 4 as the first and second cladding layers are both X 1-X, for example 0.5, and as the active layer The value of X in MgZnTe of the first and second semiconductor crystal layers 2 and 4 as the first and second cladding layers is 0. Therefore, the first and third semiconductor crystal layers 2 as the first and second cladding layers have a value of ×1−× smaller than 5, for example, 0.25.
and 4 are made of Mo ZnO, 50,5 Te, and the second semiconductor crystal layer 3 as an active layer is made of M Q Z n T e F s0
．． 25 0.75 ru. Further, the first semiconductor crystal layer 2 having p-type as the first cladding layer is L+, N, PSAs or sb
has p-type due to the introduction of
The third semiconductor crystal layer 4 having an n-type as a cladding layer has an n-type by introducing AI, Ga, I, or C1 into it. Note that when the second semiconductor crystal layer 3 as an active layer is n-type or has n-type, the n-type or n-type can be obtained by introducing the above-mentioned impurity. Note that the semiconductor crystal layers 2.3 and 4 described above can be formed by a method known per se, such as molecular beam epitaxial growth or metal organic vapor phase epitaxy. The above is the configuration of the first embodiment of the double heterojunction type semiconductor light emitting device according to the present invention. Such a double heterojunction type semiconductor light emitting device according to the present invention apparently consists of the semiconductor materials constituting the semiconductor crystal substrate 1 and the first, second and third semiconductor crystal layers 2.3 and 4. Regardless of what it is, it has the same configuration as the conventional double heterojunction semiconductor light emitting device described above. Therefore, in the case of the double heterojunction type semiconductor light emitting device according to the present invention shown in FIG. 1, the first and second
If a required power source is connected between the electrode layers 6 and 7 with the required polarity (in this example, the second electrode layer 7 side is positive),
Second semiconductor crystal layer 3 as active layer of semiconductor stack 5
A current is injected into the second semiconductor crystal layer 3 as an active layer, thereby emitting light having a wavelength corresponding to the energy band gap of the second semiconductor crystal layer 3 as an active layer. The light propagates within the interior while being confined by the first and third semiconductor crystal layers 2 and 4 as the first and second cladding layers, and is emitted to the outside from the end face of the second semiconductor crystal layer 3 as the active layer. . Furthermore, according to the double heterojunction type semiconductor light emitting device according to the present invention shown in FIG. The light emitted from the second semiconductor crystal layer 3 as an active layer is confined by the first and third semiconductor crystal layers 2 and 4 as the first and second cladding layers, and Because of the current injected into the second semiconductor crystal layer 3, the carriers in the second semiconductor crystal layer 3 as an active layer are also transferred to the first and third semiconductor crystals as the first and second crat layers. Due to the confinement by layers 2 and 4, the above-mentioned light emission can be obtained with high efficiency. However, in the case of the double heterojunction semiconductor light emitting device according to the present invention shown in FIG. Both crystal layers 2 and 4 are Mo
Zn 1-xTe, and MQ Zn
Tei, t, x 1-x For that value of X, approximately 2.3e when the value of X is O
It has an energy bandgap that increases linearly as the value of The second semiconductor crystal layer 3 is MQ Zn Te
0.25 0.75 The MgO, 25Zn O, 75Te is about 2.53e■
Therefore, the second semiconductor crystal layer 3 as an active layer has an energy band gap that allows it to emit visible short wavelength light consisting of blue light. Moreover, MqZn of the second semiconductor crystal layer 3 as an active layer
The value of X at Te (0,2×1−x 5) is the value of X at MgZn,−xTe of the first and third semiconductor crystal layers 2 and 4 as the first and second cladding layers ( 0,5>, and the first and third semiconductor crystal layers 2 and 4 as the first and second cladding layers are both made of MQ Zn Te.0.5 0 .5, the first and third semiconductor crystal layers 2 and 4 as the first and second cladding layers have a wider energy band gap than the second semiconductor crystal layer 3 as the active layer. Further, ZnTe of the semiconductor crystal substrate 1 is a semiconductor material in the case where x in the MgZnTe of the first, second and third semiconductor crystal layers 2.3 and 4 is 0. Therefore, the first, second and third semiconductor crystal layers 2.3 and 4 and the semiconductor crystal substrate 1 have substantially equal lattice constants that are sufficient to lattice match each other. First semiconductor crystal layer 2 as a layer
However, since x 1-x is made of MgZnTe, the above-mentioned impurity that gives n-type conductivity can be introduced at a relatively high concentration. The semiconductor crystal layer 2 of
It can have a relatively low specific resistance. Furthermore, a third semiconductor crystal W as a second cladding layer
4 is a first semiconductor crystal layer 2 as a first cladding layer;
According to the case of As shown in FIG. The first and third semiconductor crystal layers as the first and second cladding layers are lattice-matched to the semiconductor crystal substrate 1 together with the first semiconductor crystal layer 3 as the active layer, and as the first cladding layer. The first semiconductor crystal layer 2 and the third semiconductor crystal layer 4 as the second cladding layer exhibit a relatively low resistivity, and at the same time, the visible short wavelength of blue light can be emitted. Example 2 Next, a second example of the double heterojunction semiconductor light emitting device according to the present invention will be described. The double heterojunction semiconductor light emitting device according to the present invention has an apparent Unless the details of the semiconductor materials constituting the semiconductor crystal substrate 1 and the first, second and third semiconductor crystal layers 2, 3 and 4 are not asked, the same as described above with reference to FIG. The second embodiment of the double heterojunction type semiconductor light emitting device according to the present invention has the same configuration as the double heterojunction type semiconductor light emitting device according to the present invention.Therefore, the detailed description thereof will not be provided.However, the second embodiment of the double heterojunction type semiconductor light emitting device according to the present invention M g of the first and third semiconductor crystal layers 2 and 4 as the second cladding layer
X in Zn 1-x Te is 0.5, and Mg Zn Te in the semiconductor crystal layer as the active layer
Since X is 0.2x 1-x 5, the first and third semiconductor crystal layers 2 and 4 as the first and second cladding layers are made of Ma.
The third semiconductor crystal layer 3 as the active layer is M(10,2Zn
Main scale 5 mentioned above in Figure 1 consisting of Te 0.7
5. In place of the first embodiment of the double heterojunction semiconductor light emitting device by Akira Akira, MgZn of the first and third semiconductor crystal layers 2 and 4 as the first and second ground layers.
X of Te is 0.4x 1-x , therefore, the first and third semiconductor crystal layers 2 and 4 as the first and second cladding layers are M O□, 4Z
n 0.6T e, and X of vq Zn1-xTe of the third semiconductor crystal layer 3 as the active layer is 0.
．． 1, and therefore the first implementation of the double heterojunction semiconductor light emitting device according to the invention as described above in FIG. It has the same configuration as the example case. The above is the configuration of the second embodiment of the double heterojunction type semiconductor light emitting device according to the present invention. According to such a double heterojunction semiconductor light emitting device according to the present invention, it has the same configuration as the double heterojunction semiconductor light emitting device according to the present invention described above in FIG. 1, except for the above-mentioned matters. Similarly to the case of the double heterojunction type semiconductor light emitting device according to the present invention described above with reference to FIG. 1, light emission can be obtained with high efficiency. However, in the case of the first embodiment of the double heterojunction semiconductor light emitting device according to the present invention, the first semiconductor crystal layer as the active layer and the first and third semiconductor layers as the first and second cladding layers. The crystal layer is made of Mgx Zn1-x Te as in the case of the double heterojunction semiconductor light emitting device according to the present invention described above in FIG. 1, but the second semiconductor crystal layer 3 as the active layer is made of Mg.Zn Tol.
09e, and its MQ Zn Te is approximately 2°0.
Since it has an energy band gap of 1 09 3 eV, it has an energy band gap that allows the second semiconductor crystal layer 3 as an active layer to emit visible short wavelength light consisting of green light. In addition, first and third cladding layers are used as the first and second cladding layers.
The semiconductor crystal layers 2 and 4 are both MOo and 4Zn.
Since it is made of Te, the first and third semiconductor crystal layers 2 and 4 as the first and 0.6 second cladding layers have a wider energy band than the second semiconductor crystal layer 3 as the active layer. There is a gap. Further, since the semiconductor crystal substrate 1 is made of ZnTe as in the case of the double heterojunction semiconductor light emitting device according to the present invention described above in FIG. 1, the first, second and third semiconductor crystal layers 2. 3 and 4 and the semiconductor crystal substrate 1 are connected to the first
As in the case of the double heterojunction type conductor light emitting device according to the present invention described above with reference to the figures, they have substantially equal lattice constants sufficient to mutually lattice match. In addition, first and third cladding layers are used as the first and second cladding layers.
Since the semiconductor crystal layers 2 and 4 are made of MGX Z nl-x Te as in the case of the double heterojunction semiconductor light emitting device according to the present invention described above in FIG. , can be introduced at a relatively high concentration as in the case of the double heterojunction type semiconductor light emitting device according to the present invention described above in FIG. Similarly to the case of the double heterojunction semiconductor light emitting device according to the present invention described above with reference to FIG. 1, the semiconductor crystal layer No. 3 can have a relatively low resistivity. From the above, according to the second embodiment of the double heterojunction type semiconductor light emitting device according to the present invention, the first and third semiconductor crystal layers as the first and second cladding layers serve as the active layer. The first semiconductor crystal layer 3 and the semiconductor crystal substrate 1 are lattice matched, and the first semiconductor crystal layer 2 as the first cladding layer and the third semiconductor crystal layer 4 as the second cladding layer are lattice matched with the semiconductor crystal substrate 1. As with the case of the double heterojunction type semiconductor light emitting device according to the present invention as described above with reference to FIG. can be obtained. In addition, in the above description, the two embodiments of the double heterojunction type semiconductor light emitting device according to the present invention are merely miniaturized, and there is no space between the first semiconductor crystal layer 2 as the first cladding layer and the semiconductor crystal substrate 1. ZnTe to MgxZn1-xTe as a buffer layer having p type as the first conductivity type
ZnTe or Mg is interposed between the third semiconductor crystal layer 3 as the second cladding layer and the electrode layer 7 as an n+ type electrode layer.
It is also possible to have a structure in which a semiconductor crystal layer made of xZn1-xTe is inserted, and in the above-mentioned embodiments, p-type can be replaced with n-type, and n-type can be replaced with p-type. However, various other modifications and changes may be made without departing from the spirit of the invention.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of a double heterojunction semiconductor light emitting device according to the present invention. 1... Semiconductor crystal substrate 2.
......First semiconductor crystal layer 3 as first cladding layer ...... Second as active layer
Semiconductor crystal layer 4......Second semiconductor crystal layer 5 as second cladding layer...Semiconductor Laminate 6.7
...... Electrode layer applicant Nippon Telegraph and Telephone Corporation

Claims (1)

[Claims] 1. A first semiconductor crystal layer as a first cladding layer having a first conductivity type, and an impurity or a first semiconductor crystal layer having a first conductivity type on a semiconductor crystal substrate having a first conductivity type. Any impurity that gives a second conductivity type opposite to the first conductivity type is not intentionally introduced, or even if it is introduced, it is introduced only at a sufficiently low concentration, and the first semiconductor crystal layer a second semiconductor crystal layer as an active layer having an energy band gap narrower than that of the second semiconductor crystal layer, and a second semiconductor crystal layer having a second conductivity type and having a wider energy band gap than the second semiconductor crystal layer A semiconductor stack is formed in which a third semiconductor crystal layer as a cladding layer is stacked in that order, and a first electrode is formed on a surface of the semiconductor crystal substrate opposite to the semiconductor stack. A double heterojunction semiconductor light emitting device having a structure in which a layer is ohmically applied, and a second electrode layer is ohmically applied on a surface of the semiconductor laminate opposite to the semiconductor crystal substrate side, the above-mentioned The semiconductor crystal substrate is made of ZnTe, and the first, second and third semiconductor crystal layers are all made of Mg.
_xZn_1_-_xTe (0<x<1), provided that Mg_xZn_ of the second semiconductor crystal layer
A double heterojunction semiconductor light emitting device, wherein x in 1_-_xTe has a smaller value than x in Mg_xZn_1_-_xTe of the first and third semiconductor crystal layers.