JPH02133979A - Semiconductor light-emitting element - Google Patents

Abstract

PURPOSE:To obtain a short wave length band semiconductor light-emitting element which emits blue color, green color, etc., by making a II-VI compound semiconductor as an active layer, allowing one part of II element to be substituted for on a clad layer, and constituting a semiconductor which lattice-matches to the active layer. CONSTITUTION:A short wave length band semiconductor light-emitting element consists of an n-side clad layer 2 consisting of n-Zn0.82Mn0.18S0.98Se0.01Te0.01, an active layer 3 consisting of a ZnS0.9Se0.05Te0.05, a p-side clad layer 4 consisting of p-Zn0.82Mn0.18S0.98 Se0.01Te0.01 an insulation film 5, and electrodes 6 and 7, where a substrate 1 consists of n-GaP. Lattice constants of the substrate 1, the clad layers 2 and 4, and the active layer 3 are nearly matched, band connection is made so that entrapment of electrons and positive holes can be performed effectively into the active layer 3 and entrapment of electrons and positive holes is performed fully. Thus, by substituting one part of Zn which is II element using transition metal elements such as Mn, Fe, Co, or Ni, the layers 2 and 4 at both sides of the active layer 3 nearly lattice match to the substrate 1 and a blue wave length band injection type short wave band semiconductor light-emitting element with a sufficient carrier entrapment can be obtained.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a current injection type semiconductor light emitting device using a II-VI group compound semiconductor, and in particular to a semiconductor light emitting device in a short wavelength band that emits blue or green light. It is related to the element.

(Prior Art) There has been remarkable progress in the field of optical information in recent years, as seen in laser disks, laser printers, and the like. In these fields, red semiconductor lasers are used as light sources, but in order to support large-capacity recording, high-speed reading, high-speed printing, etc., in addition to higher output, shorter wavelength lasers are required. There is. For this reason, research on shortening the wavelength of semiconductor lasers is progressing, but so far a semiconductor laser in a short wavelength band (0.3 to 0.5 μm) that emits blue or green light has not been realized.

On the other hand, in order to utilize the light emitting diodes used in various display devices as full-color display elements, blue and green light emitting diodes are required in addition to the red color currently in use.

(Problems to be Solved by the Invention) ZnS is used as a semiconductor for light-emitting elements in short wavelength bands such as blue and green due to restrictions in bandgap width.

II-VT group compound semiconductors such as ZnSe and ZnTe are considered to be the most promising.

FIG. 1 shows the relationship between the forbidden band width and lattice constant of ZnS, ZnSe, ZnTe, and their mixed crystal systems. In addition, GaAs, GaP, InP that can be used as a substrate
, Si are also shown for reference. As can be seen from this figure, with only the Zn5SeTe system, the active layer and cladding layer are lattice matched to the substrate, and the difference in forbidden band width is 0.
, 2 eV or more cannot be obtained. Also, Zn
In the Se-ZnTe or ZnS-ZnTe heterojunction, as shown in the energy band diagrams in Figure 2 (a) and (b), the lower end of the conduction band (A) of ZnTe is the lower end of the conduction band (B) of ZnS or ZnSe. ) comes above. Therefore, although holes gather in the active layer, electrons gather in the cladding layer, which has a large forbidden band width. That is, ZnS,
In the 5eTe system, it is not possible to effectively confine electrons in the active layer, and the recombination of electrons and holes for light emission cannot occur.For this reason, a double heterostructure that operates stably cannot be obtained. In addition, the crystals of such U-VI group compound semiconductors have strong ionicity, which makes it extremely difficult to control conductivity by adding impurities.

As mentioned above, in the conventional technology, group ■, ■ group elements (Z
n, S, 'Sex Te, etc.) alone, the active layer and cladding layer are lattice matched with the substrate, and a short wavelength light emitting device having a sufficient energy barrier between the active layer and the cladding layer against electrons and holes. No double heterostructure was obtained. In addition, a semiconductor of the same composition is used for the cladding layer.
It was also difficult to create both conduction types. Therefore, semiconductor light emitting devices in short wavelength bands such as blue and green have been strongly desired, but nothing has been disclosed so far.

An object of the present invention has been made to solve the problems of the prior art described above, and is to provide a short wavelength band semiconductor light emitting device that emits blue, green, etc. light.

(Means for Solving the Problems) The present invention is characterized by: (1) A -vr group compound semiconductor is used as an active layer, and a cladding made of a semiconductor having a forbidden band width larger than that of the active layer is provided in contact with both sides of the active layer. In a semiconductor light emitting device, the cladding layer is composed of a semiconductor in which a part of the group II elements of the II-VI compound semiconductor is replaced with a transition metal, and which is substantially lattice-matched with the semiconductor constituting the active layer. .

(Example 1) FIG. 3 shows a first example according to the present invention, and is a sectional view of a short wavelength band semiconductor light emitting device. Note that in the following explanation, a short wavelength band semiconductor light emitting element that emits blue light will be taken as an example.

In the figure, 1 is an n-GaP substrate, 2 is an n-Zno substrate,
82Mno, 1aso, esseo, otTea
, ot is an n-side cladding layer with a thickness of about 2 μm; 3 is an active layer made of Zn5o9seo, o6Teo, and os and has a thickness of about 0.2 μm; 4 is a p-Zno, aJno,
+sSo, saSeo, o+Teo, ol p-side rad layer with a thickness of about 2 μm, 5 is an insulating film, 6
and 7 are electrodes. Note that the n-side cladding layer 2 is Cj
By doping the p-side rad layer 4 with Li (chlorine) and Li (lithium), a carrier concentration of 10"cm-" or more was obtained.

In this structure, the lattice constants of the substrate 1, cladding layers 2 and 4, and active layer 3 are almost matched, and the energy difference between the active layer 3 and the cladding 2 and 4 layers is about 0.3 eV. Furthermore, since the addition of Mn reduces the electron affinity of the cladding 2.4 layer, a band connection is established at the Peter interface where electrons and holes are effectively confined within the active layer 3, as shown in Figure 4. The energy difference between the conduction band and the valence band is 0.2 and 0.1 eV, respectively. Therefore, electrons and holes are sufficiently confined.

As mentioned above, the present invention uses Zn (zinc), which is a group Ⅰ element.
By replacing a part of the active layer 3 with a transition metal element such as 118n, Fe, Co, or Ni, the active layer 3 and the layers on both sides of the active layer 3 are substantially lattice matched with the substrate 1, and carriers are sufficiently confined in the active layer 3. An injection type short wavelength band semiconductor light emitting device in the blue wavelength band (wavelength band of 0.37 μm in this example) can be realized.

In addition, in the case of emitting green light, the substrate is made of GaP and the semiconductor layer composing the active layer 3 is zns+-x.
-ySexTey (o≦x≦1.0≦y≦1) by increasing the composition ratio y to make the wavelength around 0.5 μm, and Zn+-wMnwS, which is the semiconductor layer constituting the cladding layer 2.4.
+-p-qSepTeq (0≦p≦1.0≦q≦1
The composition ratio q of ゜0.05≦w≦0.5 may also be large.

(Example 2) In Example 1, GaP is used as the substrate 1 and one set of compositions is shown for the active layer 3 and cladding 2 and 4 layers, but the present invention is not limited to this composition. The substrate l is GaP or S
i, the composition of the active layer 3 is Zn5t-x-yS
exTe, (o≦x≦1.0≦y≦1.0.07≦x
+2.6y≦0.2), and the composition of the cladding layers 2 and 4 is Zr++−wMnws+ −p−qSepTeq (
0≦p≦1.0≦q≦1.0.05≦w≦0.5.
O≦p+2.6q≦0.06), it is possible to realize a short-wavelength semiconductor light-emitting device having a layer structure that is substantially lattice-matched to the substrate l, has sufficient carrier confinement, and can easily control the conduction type.

(Example 3) In Examples 1 and 2, the normal double heterostructure was used, but the active layer 3 or the cladding layer 2゜4 or both were ultra-thin films with a thickness of 300 angstroms or less and different compositions. It may be a film in which multiple layers are stacked (hereinafter referred to as a "superlattice structure"). When such a superlattice structure is adopted, there is a tendency for a zinc blend structure to be maintained even if the composition contains more Mn than in the bulk. can be done more fully.

Furthermore, when the cladding layers 2 and 4 are superlattice layers, the superlattice layer at the interface with the substrate 1 is expected to function to prevent impurity atoms from diffusing from the substrate 1. For example, Si,
Diffusion of Ga or P is prevented. Furthermore, when the active layer 3 is a superlattice layer such as a quantum well structure, it goes without saying that it exhibits characteristics as a quantum well laser.
It has many advantages, such as being able to operate at a shorter wavelength than a laser with an eTe-based bulk active layer 3.

For example, when the active layer 3 is a single layer and the cladding layer 2.44 has a superlattice structure, the active layer 3 is made of, for example, ZnS+-++
−ySexTey (0≦x≦1.0≦y≦1.0.0
7≦x+2.6y≦0.2), and the cladding 2.4 layer is Z
nl-wMnwS+-p-qSepTeq (Q≦p
≦1.0≦q≦10.05≦w≦0.8. O≦p+
2.6q≦0.06) and Zn+-w'Mnw'5
l-p'-ct'Sep゛Teq°(0≦p'≦1
．． 0≦q≦1.0.05≦w゛≦ 0.8. O≦p
'+2.6q' ≦0.06).

On the contrary, the active layer 3 has a superlattice structure consisting of a quantum well structure,
When the cladding layer 2.4 is a single layer, the active layer 3 is made of ZnS.
+−x−ySexTey (o≦x≦1.0≦y≦1.
0.07≦x+2.6y≦0.2) as a quantum well layer, Zn
+-z・Mnz'S+-11'-y・Sex・Te,
・(o≦x'≦1, 0≦y≦1, 0.05≦z'≦0
．． 8. It is a quantum well structure with a barrier layer of O≦x'+2.6y'≦0.06), and the 2nd and 4th cladding layers are Zn.
+ -wMnwS l -p -qSepTeq (
0≦p≦1゜0≦q≦1.0.05≦w≦0.5. O
≦p+2.6q≦0,06).

Furthermore, when both have a superlattice structure, the substrate 1 is SL or GaP, and the active layer 3 is ZnS r -x
-, 'SexTey (OS x≦1.0≦y≦1.0
．． 07≦x+2.6y≦0.2) as a quantum well layer, Zn1
-*'Mnz'5l-11'-ySex・Tey
・(O≦x'≦1,0≦y'≦1,0.05≦z'≦0
．． 8. It is a quantum well structure with a barrier layer of O≦x' + 2.6y'≦0.06), and the 2.4 cladding layer is
Zn+-wMnwS+-p-qSepTeq (0≦p
≦1.0≦q≦1.0.05≦w≦0.8. O≦p
+2.6q≦0.06) and Zn, -.

Mnw'S+-p・-Q'Sep'Teq' (0≦p
゛≦1,0≦q°≦1゜0.05≦w°≦0.8. O
≦p'+2.6q'≦0.06), the layer structure is almost lattice matched with the substrate 1, has sufficient carrier confinement, and can easily control the conduction type. It is possible to realize a short wavelength semiconductor light emitting device with the same characteristics.

(Example 4) When the substrate 1 is made of GaAs, Ge or ZnSe,
The active layer 3 composition is ZnS + -X -ySexTey
(0≦x≦1, 0≦y≦1.0.8≦x + 2.6y
≦1.0), and the cladding 2゜4 layer composition is Zn+-wM
nws+-p-qSepTeq (o≦p≦1゜0≦q
≦1.0.05≦w≦0.5.0.5≦p+2.6q≦
0.8), it is almost lattice matched with the substrate l,
A short-wavelength semiconductor light-emitting device with sufficient carrier confinement and a layered structure whose conduction type can be easily controlled can be realized.

(Example 5) Even if the substrate 1 is made of GaAs, Ge or ZnSe,
The active layer 3 and/or the cladding layer 2.4 may have a superlattice multilayer structure. For example, the active layer 3 is ZnS+−x−ySeJey (0≦x≦1.0≦y
≦1.0.8≦x + 2.6y≦1.0) as a quantum well layer, Zn+-z'Mnz・s+-x'-y'sex'T
ey'(0≦x'≦1, 0≦y≦1, 0.05≦z
'≦0.8. p≦
1.0≦q≦1.0.05≦w≦0.8.0.5≦p+
2.6q≦0.8) and Zn+ -sw'Mnw'
S+-p'-q'Sep' TeQ・(0≦p°
≦l.

O≦q'≦1, 0.05≦w°≦0.8. 0.5≦p
'+2.6q' ≦0.8), the short film has a layer structure that is almost lattice-matched to the substrate l, has sufficient carrier confinement, and can easily control the conduction type. A wavelength band semiconductor light emitting device can be realized.

The advantages of such a superlattice structure are similar to those described in the third embodiment.

(Example 6) When the substrate 1 is a GaAsP mixed crystal, the lattice constant takes a value of 5.45 to 5.54 angstroms depending on the composition ratio.

In this case, the composition of the active layer 3 is ZnS+-x-ySexTe
y (o≦x≦1, 0≦y≦1), cladding layers 2 and 4
The composition is Zn+-wMnwS+-p-qsepTecl
(0≦p≦1, 0≦q≦1.0.05≦w≦0.5), and the composition ratio should be selected to have a value that almost lattice matches with the substrate 1 within this range. As a result, a short-wavelength semiconductor light-emitting device with sufficient carrier confinement and a layered structure whose conduction type can be easily controlled can be realized.

(Example 7) Even when the substrate 1 is made of GaAsP mixed crystal, the active layer 3 and/or the cladding layer 2.4 may have a superlattice multilayer structure. For example, the active layer 3 is made of ZnS+-x-
ySeJey (0≦x≦1, 0≦y≦1) as a quantum well layer, Zn+-i・Mnz'5l-X'-11' S
ex'Tey'(0≦x゛≦1.0≦y'≦1, 0
．． 05≦z'≦0.8) as a barrier layer, and the cladding 2.4 layer is Zn+-JnwS+-p-
qSepTeq (0≦p≦1.0≦q≦1.0.05
≦w≦0.8) and Zn l −W'Mnw' S
l-pSep・Te,・(O≦p゛≦1.0≦q゛≦
The layer structure is a superlattice multilayer film having the following relationship: 1.0.05≦w°≦0.8), and the composition ratio may be selected within this range so as to be substantially lattice matched with the substrate 1. By doing this,
A short-wavelength semiconductor light-emitting device with sufficient carrier confinement and a layered structure whose conduction type can be easily controlled can be realized.

The advantages of such a superlattice structure are similar to those described in the third embodiment.

(Embodiment 8) When the substrate 1 is made of InP, bulk ZnS and 5eTe systems that are lattice-matched to the substrate can only emit red light, but if a quantum well structure is used, a blue light emitting device can be realized. In this case, the active layer 3 is ZnS l-x-Sex
Tey(0≦x≦1.0≦y≦1.0.85≦0.6x
+1.6y≦1.15) as the quantum well layer, Zn1-z'
Mnz'S+-x'-ySex' Te, ・(0≦
x'≦1, 0≦y'≦1, 0.05≦z'≦0.8.0
．． 85≦0.6x'+1.6y'≦1.15) as a barrier layer, and the thickness of the well layer is 100 angstroms or less. On the other hand, the cladding layers 2 and 4 are Zn+-wMnws+-p-JepTeq (0≦p
≦1,0≦q≦1.0.05≦w≦0.8.0.85≦
0.6p+1.6q≦1,15) or Zrl+-wMnws-p-qSepTeq(0
≦p≦1.0≦q≦1.0.05≦w≦0.8.0.8
5≦0.6p+ 1.6q≦1.15) and Zn+
-w'Mnw' S+ -p'-q' Sep・Dinge,・ (O≦p°≦ 1, 0≦q≦1.0.05≦
w゛≦0.8.0.85≦0.6p'+1.6q'≦
1, 15) has a layer structure that is a superlattice multilayer film that is almost lattice-matched to the substrate 1, has sufficient carrier confinement, and has a layer structure that allows easy control of conduction type, and short wavelengths in the blue wavelength range. A band semiconductor light emitting device can be realized.

The advantages of such a superlattice structure are similar to those described in the third embodiment.

In the above description, the n-type substrate 1 is assumed, but of course a structure in which the p-type substrate 1 is used and the conduction types of the cladding layers 2 and 4 are reversed may also be used. As the n-type dopant, Br
, AI, Ga, In, etc. may be used, and as the p-type dopant, Na, K, P.

As, Sb, etc. may also be used. Moreover, a transition metal element such as Fe, Co, or Ni may be used instead of Mn. Regarding the substrate 1, CuGaSe and C
A chalcopyrite semiconductor such as uAlSe may also be used.

The present invention is applicable to both lasers and light emitting diodes. In the case of a laser, it is applicable to various transverse mode control structures including a buried structure. It can also be applied to distributed feedback type or distributed Bragg reflection type lasers.

(Effects of the Invention) As described above, according to the present invention, in a light emitting element having a double heterostructure using a II-VI group compound semiconductor, particularly a Zn5SeTe system, a part of the group II element is replaced with a transition metal. By using the substituted compositions for the cladding layers 2 and 4, the substrate 1 - active layer 3 - cladding 2.4 layer is almost lattice matched, and an energy barrier is formed such that carriers are sufficiently confined in the active layer 3. In addition, a short wavelength band semiconductor light emitting device is provided in which both p and n conduction types can be easily controlled.

By using Mn, Fe, Co, or Ni as the transition metal element, it becomes possible to increase the forbidden band width of the cladding layers 2 and 4 and confine carriers in the active layer 3.

By forming the active layer 3 and the cladding layers (2, 4) each with a single semiconductor layer, it is possible to realize a short wavelength band semiconductor light emitting device that is easy to manufacture.

By configuring at least one of the active layer 3 and the cladding layers (2, 4) with a quantum well structure or a superlattice structure in which a plurality of ultra-thin films are laminated, it is possible to increase the Mn composition ratio. It is possible to realize a short wavelength band semiconductor light emitting device in which carrier confinement in the layer 3 is made easier and diffusion of impurity atoms from the substrate 1 is prevented.

Active H3 is ZnS+−x−ySexTey (0≦x≦
1.0≦y≦1), and cladding layers 2 and 4 are Zn +
-WMnwSl-9-9'SexTea (0≦p≦
1.0≦q≦1.0.05≦w≦0.5), the active layer 3 and cladding layers 2 and 4 are lattice-matched to the substrate 1 and have a short wavelength that allows carrier confinement. A band semiconductor light emitting device can be realized.

The active layer 3 is made of ZnS+-IK-,5eKTe, (o≦
x≦1.0≦y≦1) as a quantum well layer, Zn+−z' M
nz'5l-X・-y'Sex・Te,s (0≦x
It has a quantum well structure with barrier layers of °≦1, 0≦y'≦1, 0.05≦Z≦0.8), and cladding layers 2 and 4 are Zn+
-wMnws+-9-qSel, Teq (o≦p≦1゜0≦q≦1.0.05≦w≦0.8) and Zn+-i
'MnzSl-X-y' 5eX-Te, ・(0≦p'
≦1, 0≦q°≦10.05≦w°≦0.8), it is possible to increase the Mn composition ratio. It is possible to realize a short wavelength band semiconductor light emitting device in which carrier confinement becomes easier and diffusion of impurity atoms from the substrate 1 is prevented.

Substrate 1 is GaAs, Gap, InP, Si, G
By forming the active layer 3 with ZnSe or GaAsP mixed crystal, it becomes easy to lattice match the active layer 3 with the substrate 1.

For this reason, it has become possible to operate in short wavelength ranges such as blue and green, which was previously not possible with semiconductor laser diodes, and it has been widely used in consumer and information processing applications, and its effects are extremely large. .

[Brief explanation of the drawing]

Figure 1 shows ZnS, ZnSe, ZnTe and their mixed crystal systems, as well as GaAs, GaP, InP, and Si.
Figure 2 (a) is a characteristic diagram showing the relationship between the forbidden band width and lattice constant of
) and (b) are conventional ZnSe-ZnTe and ZnS
-A schematic diagram showing energy band connection in a ZnTe heterojunction, FIG. 3 is a cross-sectional view of a light emitting device having a layered structure according to the present invention, and FIG. FIG. 3 is a schematic diagram showing band connections. 1... n-GaP substrate, n-side cladding layer (n-Zno, aJno, +aS
. Seo, otTea, o+) % ・Active layer (ZnSo, eseo, osTeo, o
s), 'p-side cladding layer p-Zno. 62Mno,
+sS. Seo, otTea, o+) s - Insulating film, 6.7 - Electrode. 3 ・ 5 ・ 2 ・ 4 ・

Claims (8)

[Claims] (1) In a semiconductor light emitting device having a substrate, an active layer and a cladding layer formed on the substrate, the active layer is II-V
a group I compound semiconductor layer, the cladding layer is a group II-VI compound semiconductor having a band gap larger than the band gap of the active layer, and a part of the group II element is replaced with a transition metal element; A semiconductor light emitting device comprising a semiconductor that is substantially lattice matched with the active layer. (2) The semiconductor light emitting device according to claim 1, wherein a part of the group II elements in the active layer are replaced with a transition metal element. (3) The transition metal element is Mn, Fe, Co or Ni.
Claim 1 characterized in that it is one selected from
The semiconductor light emitting device described above. (4) The semiconductor light emitting device according to claim 1, wherein the active layer and the cladding layer are each composed of a single semiconductor layer. (5) The semiconductor light emitting device according to claim 1, wherein at least one of the active layer and the cladding layer has a superlattice structure in which a plurality of ultra-thin films are laminated. (6) The active layer is ZnS_1_-_x_-_ySe_
xTe_y (0≦x≦1, 0≦y≦1), and the cladding layer is Zn_1_−_wMn_wS_1_−_p_
−_qSe_pTe_q(0≦p≦1, 0≦q≦1, 0
．． 05≦w≦0.5). The semiconductor light emitting device according to claim 1, wherein: (7) The active layer is ZnS_1_-_x_-_ySe_
xTe_y (0≦x≦1, 0≦y≦1) as a quantum well layer,
Zn_1_-_z_'Mn_z_'S_1_-_x_'
____y_'Se_x_-_'Te_y_'(0≦x'
≦1, 0≦y'≦1, 0.05≦z'≦0.8) as a barrier layer, and the cladding layer is Zn_
1_-_wMn_wS_1_-_p_-_qSe_pT
e_q(0≦p≦1, 0≦q≦1, 0.05≦w≦0.
8) and Zn_1_−_w_'Mn_w_'S_1_
−_p_'_-_q_'Sc_p_'Te_q_'(0
≦p'≦1, 0≦q'≦1, 0.05≦w'≦0.8)
2. The semiconductor light emitting device according to claim 1, wherein the semiconductor light emitting device is constructed of a superlattice multilayer film consisting of the following. (8) The substrate is made of GaAs, GaP, InP, Si, Ge, or Zn that is substantially lattice matched to the active layer and the cladding layer.
2. The semiconductor light emitting device according to claim 1, wherein the semiconductor light emitting device is made of one selected from Se and GaAsP mixed crystal.