TW202046514A - Light emitting element and method of manufacturing light emitting element - Google Patents

Abstract

The present invention is a light emitting element having a light emitting part in which an N-type cladding layer, an active layer, and a P-type cladding layer are formed in this order, wherein the active layer includes a P-type dopant of which the concentration gradually decreases from the P-type cladding layer side to the N-type cladding layer side, and in the active layer, the average concentration of the P-type dopant in a region from the P-type cladding layer to a position corresponding to 1/3 of the thickness of the active layer is 1.0 * 1016 atoms/cm3 or more and 3.0 * 1017 atoms/cm3 or less. Accordingly, provided are: the light emitting element which has excellent luminance characteristics with respect to the environmental temperature and which suppresses the deterioration of life characteristics; and a method of manufacturing the same.

Description

Light-emitting element and manufacturing method of light-emitting element

The present invention relates to a light-emitting element and a method for manufacturing a light-emitting element, and more particularly to a light-emitting element and a method for manufacturing a light-emitting element that have good luminance characteristics corresponding to ambient temperature and suppress deterioration in lifetime characteristics.

AlGaInP-based materials have the largest direct transition type energy gap in III-V compound semiconductor mixed crystals other than nitrides, and are attracting attention as materials for visible light emitting devices in the 550-650 nm band (green-red band). Such an AlGaInP-based light-emitting element having an active layer composed of AlGaInP with a large direct transition type energy gap can achieve higher brightness than those composed of indirect transition type materials such as GaP and GaAsP (for example, Patent Document 1 ).

4 is a schematic cross-sectional view showing an example of a conventional AlGaInP-based light-emitting device. The light-emitting element 310 has on the GaAs starting substrate 300: a GaAs buffer layer with a thickness of 0.1 to 1.0 μm; for example, an AlInP etching stop layer 302 with a thickness of 1.0 μm; for example, an N-type AlGaInP sheath layer 303 with a thickness of 1.0 μm; for example, a thickness of 0.9 μm The AlGaInP active layer 304; for example, the P-type AlGaInP sheath layer 305 with a thickness of 1.0 μm; the P-type InGaP buffer layer 306 that eases the lattice misalignment with the current propagation layer; the current applied to the element is propagated and diffused to have light The extraction function is, for example, a P-type GaP current propagation layer 307 with a thickness of 5.0 μm. The GaAs buffer layer may not be required. Note that the electrodes of the light-emitting element and the like are omitted in FIG. 4.

Here, as for the N-type dopant, for example, Si, S, Se, etc. are doped into the N-type sheath layer 303. In addition, for P-type dopants, Zn, Mg, Te, etc. are doped into the P-type sheath layer 305, the P-type buffer layer 306, and the P-type current propagation layer 307.

The N-type sheath layer 303 is composed of an epitaxial layer with more than one composition and doping level, and the P-type sheath layer 305 is composed of an epitaxial layer with more than one composition and doping level. The active layer 304 is a uniformly composed surface-type active layer, or a multiple junction type active layer in which a light-emitting composite layer and a barrier layer having an energy band gap larger than the composition of the light-emitting composite layer are multiple-joined.

In addition, when forming the light-emitting portion of a light-emitting element (such as an AlGaInP-based light-emitting element) by epitaxial growth, in order to avoid deterioration of life characteristics, it is necessary to remain in the active layer, or to diffuse or migrate during the life test. The concentration of the material is designed to be extremely small. However, making the concentration of the dopant in the active layer extremely small can improve the life characteristics, but on the other hand, the change in brightness corresponding to the ambient temperature tends to become larger. In addition, in order to improve the brightness characteristics corresponding to the ambient temperature, it is known that excessive placement of dopants in the active layer is effective. However, the dopants that are excessively added to the active layer can improve the brightness characteristics, but become a source of dislocations and defects, and significantly deteriorate the lifetime characteristics.

Therefore, a light-emitting element with good luminance characteristics corresponding to ambient temperature has poor lifetime characteristics. On the other hand, a light-emitting element with good lifetime characteristics has poor luminance characteristics corresponding to ambient temperature. It is desired to realize two light-emitting elements with good characteristics. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Application Publication No. 2005-150645

[The problem to be solved by the invention]

The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide a light-emitting element and a method of manufacturing the same, which have good luminance characteristics corresponding to ambient temperature and suppress deterioration of lifetime characteristics. [The way to solve the problem]

In order to achieve the above object, the present invention provides a light-emitting element including a light-emitting portion in which an N-type sheath layer, an active layer, and a P-type sheath layer are sequentially formed, wherein the active layer includes: P-type dopants, Its concentration gradually decreases from the P-type sheath layer side to the N-type sheath layer side; and in the active layer, the area from the P-type sheath layer to the position of 1/3 of the thickness of the active layer The average P-type dopant concentration is 1.0×10 ¹⁶ atoms/cm ³ or more and 3.0×10 ¹⁷ atoms/cm ³ or less.

In such an active layer, as long as the average P-type dopant concentration in the region from the P-type sheath layer to the position of 1/3 of the thickness of the active layer is 1.0×10 ¹⁶ atoms/cm ³ or more, it can Increase the light output and increase the brightness characteristics corresponding to the ambient temperature. In addition, the average P-type dopant concentration in the region from the P-type sheath layer to the position of 1/3 of the thickness of the active layer is 3.0×10 ¹⁷ atoms/cm ³ or less, and the active layer is derived from P The P-type dopant concentration curve that gradually decreases from the side of the N-type sheath layer to the side of the N-type sheath layer can suppress the deterioration of the life characteristics.

In addition, the aforementioned light-emitting portion can be determined to be composed of an AlGaInP-based compound semiconductor.

In particular, the present invention can be suitably used for a light-emitting element in which the light-emitting portion is composed of an AlGaInP-based compound semiconductor.

In addition, it can be determined as the average P-type dopant concentration in the active layer from the position of the P-type sheath layer from the position of 1/3 of the thickness of the active layer to the position of 2/3 of the thickness of the active layer It is 0.3×10 ¹⁶ atoms/cm ³ or more and 3.0×10 ¹⁶ atoms/cm ³ or less.

As long as the P-type dopant concentration is within the above-mentioned numerical range in the above-mentioned region, the deterioration of the lifetime characteristics can be suppressed more reliably.

At this time, it can be determined that in the active layer, the average P-type dopant concentration in the region from the position of 2/3 of the thickness of the active layer from the P-type sheath layer to the N-type sheath layer is 0.3×10 ¹⁶ atoms/cm ³ or less.

As long as the P-type dopant concentration is within the above-mentioned numerical range in the above-mentioned region, the deterioration of the lifetime characteristics can be further reliably suppressed.

In addition, the present invention provides a method of manufacturing a light-emitting element, the light-emitting element having a light-emitting portion formed in this order of an N-type sheath layer, an active layer, and a P-type sheath layer, characterized in that: in the active layer, the P-type The dopant concentration gradually decreases from the P-type sheath layer side to the N-type sheath layer side, and the P-type dopant is doped as follows to manufacture: In the active layer, from the P-type sheath layer The average P-type dopant concentration in the region from the position of 1/3 of the thickness of the active layer is 1.0×10 ¹⁶ atoms/cm ³ or more and 3.0×10 ¹⁷ atoms/cm ³ or less.

As long as it is manufactured so that the average P-type dopant concentration in the active layer from the P-type sheath layer to the position of 1/3 the thickness of the active layer is 1.0×10 ¹⁶ atoms/cm ³ or more, then Increase the light output and improve the brightness characteristics corresponding to the ambient temperature. In addition, the average P-type dopant concentration in the region from the P-type sheath layer to the position where the thickness of the active layer is 1/3 of the thickness of the active layer is 3.0×10 ¹⁷ atoms/cm ³ or less, and is defined as being in the active layer The P-type dopant concentration curve gradually decreasing from the P-type sheath layer side to the N-type sheath layer side can suppress the deterioration of life characteristics.

In this case, the aforementioned light-emitting portion can be determined to be composed of an AlGaInP-based compound semiconductor.

In particular, the present invention can be suitably used to manufacture a light-emitting element in which the light-emitting portion is composed of an AlGaInP-based compound semiconductor.

In addition, when the P-type dopant is doped into the active layer, it can be doped as follows: In the active layer, from the P-type sheath layer, the thickness of the active layer is 1/3 to 2 The average P-type dopant concentration in the region up to the position having the thickness of /3 is 0.3×10 ¹⁶ atoms/cm ³ or more and 3.0×10 ¹⁶ atoms/cm ³ or less.

As long as the P-type dopant concentration is determined to be in the above-mentioned numerical range in the above-mentioned region, deterioration of the lifetime characteristics can be suppressed more reliably.

At this time, when the aforementioned P-type dopant is doped into the aforementioned active layer, it can be doped as follows: In the aforementioned active layer, from the aforementioned P-type sheath layer to a position of 2/3 of the thickness of the aforementioned active layer The average P-type dopant concentration in the region up to the N-type sheath layer is 0.3×10 ¹⁶ atoms/cm ³ or less.

As long as the P-type dopant concentration is set within the above-mentioned numerical range in the above-mentioned region, the deterioration of the lifetime characteristics can be further reliably suppressed.

In addition, the aforementioned P-type dopant can be doped to the aforementioned active layer by the following method: Gas doping is performed while forming the aforementioned active layer. Or, the aforementioned P-type dopant can be doped to the aforementioned active layer by the following method: After the active layer is formed, the P-type sheath layer doped with the P-type dopant is formed and heat treatment is applied to diffuse the P-type dopant that has been doped into the P-type sheath layer to the active layer. .

In this way, by doping by gas doping or heat treatment, it is possible to easily dope to the above-mentioned regions with the above-mentioned concentration curve. [Effects of Invention]

As described above, as long as the light-emitting element and the method of manufacturing the light-emitting element of the present invention can increase the light output, the brightness characteristics corresponding to the ambient temperature are good, and the deterioration of the lifetime characteristics is suppressed.

[Preferable form for implementing invention]

As described above, we hope to develop light-emitting elements (especially AlGaInP-based LEDs) that have good lifetime characteristics and brightness characteristics corresponding to ambient temperature. The inventor of the present case has deliberately discussed this subject repeatedly and learned that in a light-emitting element having a light-emitting portion formed in this order at least an N-type sheath layer, an active layer, and a P-type sheath layer, the brightness characteristics corresponding to the ambient temperature are changed The huge reason is due to the behavior of the carriers in the P-type carrier-rich region in the active layer region. Therefore, the active layer region near the P-type sheath layer is specifically 1/3 of the full thickness of the active layer. The region close to the P-type sheath layer is designated as the P-type active layer region, and the P-type dopant concentration in the P-type active layer region is determined to be 1.0×10 ¹⁶ atoms/cm ³ or more and 3×10 ¹⁷ atoms/cm ³ In the following, in order to prevent excessive diffusion into the active layer, during epitaxial growth, the P-type dopant impurities are gradually reduced from the side of the P-type sheath layer to the side of the N-type sheath layer. The method of doping into the active layer by the concentration curve of, can produce a light-emitting element with good characteristics of brightness and lifetime characteristics corresponding to the ambient temperature, and further studies have completed the present invention.

Hereinafter, the embodiments of the present invention will be described in further detail with reference to the drawings, but the present invention is not limited to this. (First Embodiment) The first embodiment of the light-emitting device of the present invention is shown in FIG. 1. As shown in FIG. 1, the light-emitting element 110 of the first embodiment has a GaAs buffer layer with a thickness of 0.1 to 1.0 μm, such as an AlInP etching stop layer 102 with a thickness of 1.0 μm, on a GaAs starting substrate 100; AlGaInP sheath layer 103; for example, an AlGaInP active layer 104 with a thickness of 0.9 μm; for example, a P-type AlGaInP sheath layer 105 with a thickness of 1.0 μm; a P-type InGaP buffer layer 106 that relaxes lattice misalignment with the current propagation layer; and The current applied to the element propagates and diffuses, and has a light extraction function, for example, a P-type GaP current propagation layer 107 having a thickness of 5.0 μm. There may be no GaAs buffer layer. In addition, the electrodes of the light-emitting element and the like are omitted in FIG. 1.

Here, one or more of Si, S, and Se is doped into the N-type sheath layer 103 as an N-type dopant, and one or more kinds of Zn, Mg, and Te are doped into the P-type sheath layer 105 , P-type buffer layer 106 and P-type current propagation layer 107 are used as P-type dopants.

The N-type sheath layer 103 is composed of an epitaxial layer with more than one composition and doping level, and the P-type sheath layer 105 is composed of an epitaxial layer with more than one composition and doping level.

The active layer 104 is composed of a surface body type active layer of uniform composition. The active layer 104 is doped with P-type dopants (inclined doping) of decreasing concentration from the P-type sheath layer 105 toward the N-type sheath layer 103 in a gentle or stepwise manner, for example. The following shows an example of doping two kinds of Zn and Mg as P-type dopants, but the present invention is not limited to this, for example, only Zn may be doped, or three or more kinds may be doped. Furthermore, in a more preferable example of the present invention, the light-emitting portion (N-type sheath layer, active layer, P-type sheath layer) is described as being composed of AlGaInP-based compound semiconductors, but it is not limited to this.

Fig. 2 shows an explanatory diagram of the average P-type dopant concentration in the active layer. Here, the direction from the P-type sheath layer 105 to the N-type sheath layer 103 is defined as the depth direction of the active layer 104, and the interface between the active layer 104 and the P-type sheath layer 105 is defined as the reference of the depth position. The above-mentioned oblique doping concentration curve is calculated from the P-type sheath layer 105 to the depth 1/3 position (that is, from the P-type sheath layer 105 to the 1/3 thickness of the active layer 104) The average P-type dopant concentration is 1.0×10 ¹⁶ atoms/cm ³ or more and 3×10 ¹⁷ atoms/cm ³ or less. Specifically, for P-type dopants, the average concentration of Zn is designed to be, for example, 5×10 ¹⁶ atoms/cm ³ , and the average concentration of Mg is designed to, for example, 1×10 ¹⁶ atoms/cm ³ (the total value of the average concentration : 6×10 ¹⁶ atoms/cm ³ ). In addition, in the region up to 1/3 of the depth, if the type of P-type dopant to be doped is one type, the average concentration of the one type itself may fall within the above-mentioned concentration range, and if it is If there are more than two types, the sum of their average concentrations should fall within the above-mentioned concentration range.

As described above, as long as the P-type dopant is obliquely doped and the average concentration of the region up to the depth 1/3 is 3.0×10 ¹⁷ atoms/cm ³ or less, the deterioration of the lifetime characteristics can be suppressed. In addition, since the average concentration of the region up to the depth 1/3 is 1.0×10 ¹⁶ atoms/cm ³ or more, the light output can be improved, and the brightness characteristic corresponding to the ambient temperature can be improved. In this way, when the concentration curve of the P-type dopant in the active layer 104 satisfies the above-mentioned conditions, it is possible to balance the improvement of the brightness characteristics corresponding to the ambient temperature and the suppression of the deterioration of the lifetime characteristics that cannot be achieved by conventional products.

The following describes an experiment for investigating the effect of the above-mentioned present invention. (Experiment) On a GaAs substrate with a 15-degree tilt in the [001] direction, the following layers are sequentially stacked using the metal-organic vapor phase epitaxy (MOVPE) method to form a light-emitting element wafer: 1.0μm thick (Al _x Ga _{1 － x} ) _y In _{1 － y} P (0≦x≦1, 0.4≦y≦0.6) an etching stop layer; 1.0μm thick N-type sheath layer; 0.9μm thick layer ( Active layer composed of Al _x Ga _{1 - x} ) _y In _{1 - y} P (0≦x≦1, 0.4≦y≦0.6); consisting of (Al _x Ga _{1 － x} ) _y In _{1 － y} P(0≦ x ≦ 1,0.4 ≦ y ≦ 0.6) P -type layer of 1.0μm thickness of the sheath is formed; a _{Ga y in 1 - y P (} 0.0 ≦ y ≦ 1.0) consisting of an intermediate layer (buffer layer) is formed; a GaP current spreading layer (current spreading layer) with a thickness of 0.5μm or more. Furthermore, electrodes are formed, wafer dicing is performed, and wire bonding is performed to manufacture a light-emitting element.

In addition, the active layer is composed of a uniformly composed (Al _x Ga _{1 - x} ) _y In _{1 - y} P (0≦x≦1, 0.4≦y≦0.6) layer. Furthermore, the active layer is doped with P-type dopants in a manner that the concentration gradually decreases from the P-type sheath layer toward the N-type sheath layer. At this time, by changing the average concentration of the region from the P-type sheath layer of the active layer to the depth 1/3 position, a plurality of light-emitting elements with different average concentrations in the region are manufactured. In addition, in each light-emitting element, experiments were performed on the relative light output ratio at 0°C and 60°C and lifetime characteristics. The results are shown in Table 1.

【Table 1】 Average concentration (atoms/cm ³ ) Relative light output ratio (0℃vs60℃) Life characteristics (%) 3.00×10 ¹⁵ 0.8 93 6.00×10 ¹⁵ 0.8 92 1.00×10 ¹⁶ 0.86 91 3.00×10 ¹⁶ 0.86 87 6.00×10 ¹⁶ 0.87 85 1.00×10 ¹⁷ 0.89 83 3.00×10 ¹⁷ 0.9 81 6.00×10 ¹⁷ 0.9 61

As shown in Table 1, it is known that as long as the average concentration of the area from the P-type sheath layer to the depth 1/3 of the active layer is 1.0×10 ¹⁶ atoms/cm ³ or more in the obliquely doped active layer, then The relative light output ratio is 0.86 or higher, which is closer to 1, and can reduce the output change corresponding to the ambient temperature. In addition, it is found that as long as it is 3.0×10 ¹⁷ atoms/cm ³ or less, the lifetime characteristic can be 81% or more, and the deterioration can be suppressed. From these results, it is known that in order to have both good brightness characteristics corresponding to ambient temperature and good lifetime characteristics, it is necessary to set 1.0×10 ¹⁶ atoms/cm ³ or more in the above-mentioned region of the obliquely doped active layer. The concentration range is 3.0×10 ¹⁷ atoms/cm ³ or less.

Moreover, in the first embodiment of FIG. 1, it is more preferable to be a region from a position of 1/3 of the depth of the P-type sheath layer 105 to a position of 2/3 of the depth of the P-type sheath layer 105 (that is, from the P-type sheath layer 105) The active layer 104 has an average P-type dopant concentration of 0.3×10 ¹⁶ atoms/cm ³ or more, and 3.0×10 ¹⁶ atoms/ cm ³ or less. Specifically, the average concentration of Zn is designed to be, for example, 2×10 ¹⁶ atoms/cm ³ , and the average concentration of Mg is designed to, for example, 0.5×10 ¹⁶ atoms/cm ³ (the total value of the average concentration: 2.5×10 ¹⁶ atoms/cm ³ ). As long as it is in the above-mentioned concentration range, deterioration of life characteristics can be suppressed more reliably.

Furthermore, the area from the depth of 2/3 of the P-type sheath layer 105 to the side of the N-type sheath layer 103 (that is, the thickness of 2/3 of the active layer 104 from the P-type sheath layer 105) The average P-type dopant concentration (specifically, the sum of the average concentrations of Zn and Mg) of the region from the position to the N-type sheath layer 103 is preferably 0.3×10 ¹⁶ atoms/cm ³ or less. In addition, the lower limit is not particularly limited, but can be set to, for example, 0 atoms/cm ³ or more. As long as the concentration is in the above-mentioned concentration range, the deterioration of the lifetime characteristics can be further reliably suppressed.

(Second Embodiment) The second embodiment of the light-emitting device of the present invention is shown in FIG. 3. As shown in FIG. 3, the light-emitting element 210 of the second embodiment has on the GaAs starting substrate 200: for example, a GaAs buffer layer with a thickness of 0.5 μm; for example, an AlInP etching stop layer 202 with a thickness of 1.0 μm; for example, an N-type AlGaInP with a thickness of 1.0 μm The sheath layer 203; for example, the AlGaInP active layer 204 with a thickness of 0.48 μm; for example, the P-type AlGaInP sheath layer 205 with a thickness of 1.0 μm; the P-type InGaP buffer layer 206 that relaxes the lattice misalignment with the current propagation layer; and The current applied to the element propagates and diffuses, and has a light extraction function, for example, a P-type GaP current propagation layer 207 with a thickness of 5.0 μm. There may be no GaAs buffer layer. In addition, the electrodes of the light-emitting element and the like are omitted in FIG. 3.

Doping more than one of Si, S, and Se into the N-type sheath layer 203 as an N-type dopant, and doping more than one of Zn, Mg, and Te into the P-type sheath layer 205 and P-type The buffer layer 206 and the P-type current propagation layer 207 serve as P-type dopants.

The N-type sheath layer 203 is composed of an epitaxial layer with more than one composition and doping level, and the P-type sheath layer 205 is composed of an epitaxial layer with more than one composition and doping level.

In the light-emitting element 210 of the second embodiment, the active layer 204 is a multiple junction type active layer in which a light-emitting composite layer composed of AlGaInP and a barrier layer having an energy band gap larger than the composition of the light-emitting composite layer are multiple-joined Constituted. The barrier layer has a higher Al composition than the AlGaInP of the light-emitting composite layer. In addition, the thickness of the barrier layer may be set to be thinner than the De Broglie wavelength where the wave function overlaps, or may be set to be thicker. For example, the thickness of the light-emitting composite layer is 8 nm, the thickness of the barrier layer is 8 nm, and the active layer structure is 30 pairs.

The active layer 204 is doped with P-type dopants (inclined doping) of decreasing concentration from the P-type sheath layer 205 toward the N-type sheath layer 203 in a gentle or stepwise manner, for example. The following shows an example in which two kinds of Zn and Mg are doped as P-type dopants, but it is the same as in the first embodiment, and is not limited to this.

In the above-mentioned oblique doping concentration curve, the average P-type dopant concentration in the region from the P-type sheath layer 205 to the depth 1/3 position is 1.0×10 ¹⁶ atoms/cm ³ or more and 3×10 ¹⁷ atoms/ cm ³ or less. Specifically, for P-type dopants, the average concentration of Zn is designed to be, for example, 5×10 ¹⁶ atoms/cm ³ , and the average concentration of Mg is designed to, for example, 1×10 ¹⁶ atoms/cm ³ (the total value of the average concentration : 6×10 ¹⁶ atoms/cm ³ ). As long as this is the case, it is possible to achieve both good luminance characteristics corresponding to ambient temperature and good lifetime characteristics.

In addition, the average P-type dopant concentration in the region from the position 1/3 of the depth to the position 2/3 of the depth from the P-type sheath layer 205 is preferably 0.3×10 ¹⁶ atoms/cm ³ or more and 3.0×10 ¹⁶ atoms/cm ³ or less. Specifically, the average concentration of Zn is designed to be, for example, 2×10 ¹⁶ atoms/cm ³ , and the average concentration of Mg is designed to, for example, 0.5×10 ¹⁶ atoms/cm ³ (the total value of the average concentration: 2.5×10 ¹⁶ atoms/cm ³ ). Furthermore, the average P-type dopant concentration in the region from the depth 2/3 of the P-type sheath layer 205 to the side of the N-type sheath layer 203 (specifically, the sum of the average concentrations of Zn and Mg) ) Is preferably 0.3×10 ¹⁶ atoms/cm ³ or less. In addition, the lower limit is not particularly limited, and can be set to, for example, 0 atoms/cm ³ or more. As long as the above-mentioned regions are within these concentration ranges, the deterioration of the lifetime characteristics can be further reliably suppressed.

Next, the manufacturing method of the light-emitting element of the present invention will be explained. In addition, the case of manufacturing the light-emitting element 110 of FIG. 1 is taken as an example for description. Also, regarding the doping method of the active layer, the method using gas doping (the first manufacturing method) and the doping method using heat treatment (the second manufacturing method) are described as examples, but the doping method of the active layer is Not limited to this. (First manufacturing method) First, an example of doping to the active layer by gas doping will be described. The GaAs starting substrate 100 is prepared as a growth substrate. After cleaning, it is placed in a MOVPE (Metal Organic Vapor Phase Epitaxy) furnace to epitaxially grow AlInP etching stop layer 102 and N-type on the GaAs starting substrate 100 The AlGaInP sheath layer 103, the AlGaInP active layer 104, the P-type AlGaInP sheath layer 105, and the P-type InGaP buffer layer 106.

In addition, the epitaxial growth of the above-mentioned layers can be performed by the well-known MOVPE method. Although not limited to this as the source gas of the component sources of Al, Ga, In, and P, for example, the following can be used. ・Al source gas: trimethyl aluminum (TMAl), triethyl aluminum (TEAl), etc. ・Ga source gas: Trimethylgallium (TMGa), Triethylgallium (TEGa), etc. ・In source gas: trimethyl indium (TMIn), triethyl indium (TEIn), etc. ・P source gas: trimethylphosphorus (TMP), triethylphosphorus (TEP), phosphine (PH3), etc.

In addition, the doping of dopants for each layer can be performed by gas doping. The active layer and other layers can be grown epitaxially and gas doped. As for the dopant gas, for example, the following can be used. (P-type dopant) ・Zn source: dimethyl zinc (DMZn), diethyl zinc (DEZn), etc.・Mg source: Bis (cyclopentadiene) magnesium (Cp ₂ Mg), etc.・Te source: dimethyl tellurium (DMTe), diethyl tellurium (DETe), etc. (N-type dopants) ・Si source: silicon hydride such as silane, etc.・S source: hydrogen sulfide (H ₂ S), etc.・Se source: hydrogen selenide, etc.

In addition, during this gas doping, the P-type dopant in the active layer 104 is set as the concentration curve of the inclined doping as shown in FIG. 2. That is, the active layer 104 is doped obliquely in such a way that the concentration of the P-type dopant gradually decreases from the side of the P-type sheath layer 105 to the side of the N-type sheath layer 103. And the doping is as follows: the average P-type dopant concentration in the region from the P-type sheath layer 105 to the depth 1/3 position is 1.0×10 ¹⁶ atoms/cm ³ or more and 3.0×10 ¹⁷ atoms /cm ³ or less. The flow rate of the dopant gas can be controlled by, for example, a mass flow controller, and the gas doping can be easily performed with the concentration curve described above. Due to the thermal effect during epitaxial growth, it is more likely to become a concentration curve that shifts to the thermal equilibrium side than the desired concentration curve. In this regard, it is only necessary to appropriately adjust the flow rate and the like in consideration of the deviation to perform gas doping to achieve a desired concentration curve. Moreover, as long as the P-type dopant in the active layer has such a concentration curve, as described above, it is possible to achieve both the improvement of the brightness characteristic corresponding to the ambient temperature and the suppression of the deterioration of the lifetime characteristic.

In addition, when the P-type dopant is doped into the active layer 104, it is preferable to dope as follows: In the active layer 104, from the position of the depth 1/3 of the P-type sheath layer 105 to the position of 2/3 of the depth The average P-type dopant concentration of the region is 0.3×10 ¹⁶ atoms/cm ³ or more and 3.0×10 ¹⁶ atoms/cm ³ or less. Furthermore, the doping is preferably as follows: In the active layer 104, the average P-type dopant concentration in the region from the position of 2/3 of the depth of the P-type sheath layer 105 to the side of the N-type sheath layer 103 is 0.3 ×10 ¹⁶ atoms/cm ³ or less. In addition, the lower limit is not particularly limited, and can be set to, for example, 0 atoms/cm ³ or more. As long as the above-mentioned regions are within these concentration ranges, the deterioration of the lifetime characteristics can be further reliably suppressed.

Thereafter, the P-type GaP current propagation layer 107 was vapor-grown by the HVPE method (Hydride Vapor Phase Epitaxy method). In the HVPE method, specifically, for example, by heating metal Ga to maintain a predetermined temperature, and introducing hydrogen chloride to the metal Ga, GaCl is generated by the reaction of the following formula (1), and it interacts with carrier gas, which is H ₂ The gas is supplied to the substrate together. Ga (liquid) + HCl (gas) → GaCl (gas) + 1/2H ₂ (gas)... (1) The growth temperature can be set at 640°C or higher and 860°C or lower. In addition, the group V element P, such as PH ₃ , is supplied to the substrate together with H ₂ which is a carrier gas. Furthermore, for example, Zn can be supplied as a P-type dopant in the form of dimethyl zinc (DMZn), and the current propagation layer 107 can be formed by the reaction shown in the following formula (2). GaCl (gas) + PH ₃ (gas) → GaP (solid) + HCl (gas) + H ₂ (gas)...(2)

(Second manufacturing method: doping by heat treatment) Next, an example of doping to the active layer by heat treatment will be described. Basically, it is performed in the same manner as the first manufacturing method, starting from the preparation of the starting substrate 100 to the formation of the buffer layer 106. Among them, considering that the P-type dopant is diffused from the P-type sheath layer 105 to the active layer 104 by heat treatment for doping, the active layer 104 is determined to be undoped during epitaxial growth. In addition, the P-type sheath layer 105 can also be doped with P-type dopants at a higher concentration than in the first manufacturing method.

More specifically, the P-type dopant concentration of the P-type sheath layer 105, for example, when Zn and Mg are set as P-type dopants, the concentration of Zn can be set to 1.0×10 ¹⁶ to 3.0×10 ¹⁸ The concentration of atoms/cm ³ and Mg is set to a concentration range of 1.0×10 ¹⁶ to 5.0×10 ¹⁷ atoms/cm ³ . As long as it is in this concentration range, the next procedure, the heat treatment procedure, can be set as the inclined doping concentration curve shown in FIG. 2 more reliably.

After forming at least the layers up to the P-type sheath layer 105 as described above (in this example, even the buffer layer 106 is formed), in a MOVPE furnace, for example, in a PH ₃ furnace atmosphere, apply 700°C or more for 3 hours or more Heat treatment. Here, the heat treatment is set at 700°C (the same temperature as during epitaxial growth) for 8 hours. By this heat treatment, it can be easily determined as the inclined doping concentration curve shown in FIG. 2. By applying heat treatment, the dopant diffuses from the P-type sheath layer 105 into the active layer 104 according to the diffusion method, forming a concentration curve that gradually decreases toward the N-type sheath layer 103.

In addition, the temperature and time of the heat treatment are not particularly limited, and can be appropriately determined to obtain a desired gradient doping concentration profile. Moreover, as long as it is carried out in a PH ₃ furnace atmosphere as described above, it is preferable to effectively prevent P (phosphorus) from detaching from the surface of the epitaxial layer.

Thereafter, in the same manner as in the first manufacturing method, the current propagation layer 107 is formed by the HVPE method. In addition, in the above example, the heat treatment is performed after the buffer layer 106 is formed. However, the heat treatment may not be performed at this timing. Instead, heat treatment is applied after the current propagation layer 107 is formed (in an HVPE furnace, PH ₃ furnace atmosphere, 700°C or higher , 3 hours or more, especially 8 hours at 700°C), a gradient doping concentration curve is formed in the active layer 104. [Example]

Examples and comparative examples of the present invention are shown below to explain the present invention more specifically, but the present invention is not limited thereto. (Example 1) The light-emitting element of the present invention was manufactured by the manufacturing method of the present invention as follows. On a GaAs substrate with a 15-degree tilt in the [001] direction, a metal-organic vapor phase epitaxy (MOVPE) method was used to form a light-emitting element wafer with the following layers sequentially stacked: 1.0μm thick (Al _x Ga _{1 － x} ) _y In _{1 － y} P (0≦x≦1, 0.4≦y≦0.6) composed of an etching stop layer; 1.0μm thick N-type sheath layer; 0.9μm thick (Al _x Ga _{1 － x} ) _y In _{1 － y} P (0≦x≦1, 0.4≦y≦0.6) composed of an active layer; composed of (Al _x Ga _{1 － x} ) _y In _{1 － y} P (0≦x≦1 , 0.4 ≦ y P-type layer 1.0μm thick sheath constituted ≦ 0.6); a _{Ga y in 1 - y P (} 0.0 ≦ y ≦ 1.0) consisting of an intermediate layer (buffer layer) is formed; having more than 0.5μm Thickness of GaP current spreading layer (current spreading layer).

The active layer is composed of a uniformly composed (Al _x Ga _{1 - x} ) _y In _{1 - y} P (0≦x≦1, 0.4≦y≦0.6) layer. The active layer is doped with P-type dopants (both Zn and Mg) in a manner that the concentration gradually decreases from the P-type sheath layer to the N-type sheath layer. Specifically, an active layer is formed and DEZn and Cp ₂ Mg are flowed to perform gas doping. Concentration curve. In the interface with the P-type sheath layer, the concentration of Zn as the P-type dopant is 5×10 ¹⁶ atoms/cm ³ , and the concentration of Mg as the P-type dopant is 1×10 ¹⁶ atoms /cm ³ . In addition, the average Zn concentration in the area from the P-type sheath layer to a depth of 0.3 μm (1/3 of the total thickness of the active layer 0.9 μm) is 2×10 ¹⁶ atoms/cm ³ , and the average Mg concentration is 0.5×10 ¹⁶ atoms/cm ³ (Total average concentration: 2.5×10 ¹⁶ atoms/cm ³ ). In addition, the average concentration of Zn in the region from the position with a depth of 0.3 μm to the position with a depth of 0.6 μm (from 1/3 to 2/3 of the total thickness of 0.9 μm) is 0.5×10 ¹⁶ atoms/cm ³ , and the average Mg concentration The concentration is 0.2×10 ¹⁶ atoms/cm ³ (total value of average concentration: 0.7×10 ¹⁶ atoms/cm ³ ). The sum of the average concentrations of Mg and Zn in the subsequent depth (from the position of the depth 2/3 to the N-type sheath layer) is 0.3×10 ¹⁶ atoms/cm ³ or less. The electrodes are formed on the wafer thus manufactured, the wafer is diced, and then wire bonding is performed to manufacture a light-emitting element.

(Example 2) The light-emitting element of the present invention was manufactured by the manufacturing method of the present invention as follows. On a GaAs substrate with a 15-degree tilt in the [001] direction, a metal-organic vapor phase epitaxy (MOVPE) method was used to form a light-emitting element wafer with the following layers sequentially stacked: 1.0μm thick (Al _x Ga _{1 － x} ) _y In _{1 － y} P (0≦x≦1, 0.4≦y≦0.6) composed of an etching stop layer; 1.0μm thick N-type sheath layer; 0.48μm thick (Al _x Ga _{1 － x} ) _y In _{1 － y} P (0≦x≦1, 0.4≦y≦0.6) composed of an active layer; composed of (Al _x Ga _{1 － x} ) _y In _{1 － y} P (0≦x≦1 , 0.4 ≦ y P-type layer 1.0μm thick sheath constituted ≦ 0.6); a _{Ga y in 1 - y P (} 0.0 ≦ y ≦ 1.0) consisting of an intermediate layer (buffer layer) is formed; having more than 0.5μm Thickness of GaP current spreading layer (current spreading layer).

The active layer is composed of the following multiple barrier active layers alternately laminated: the first composition (Al _x Ga _{1 - x} ) _y In _{1 - y} P (0≦x≦1, 0.4≦y≦0.6 ) A light-emitting composite layer composed of a layer; and a barrier layer composed of a second composition (Al _x Ga _{1 - x} ) _y In _{1 - y} P (0≦x≦1, 0.4≦y≦0.6) layer. The Al ratio of the first composition is set to a lower ratio than the Al ratio of the second composition.

The active layer is doped with P-type dopants (both Zn and Mg) in a manner that the concentration gradually decreases from the P-type sheath layer to the N-type sheath layer. Specifically, an active layer is formed and DEZn and Cp ₂ Mg are flowed to perform gas doping. Concentration curve. In the interface with the P-type sheath layer, the concentration of Zn as the P-type dopant is 5×10 ¹⁶ atoms/cm ³ , and the concentration of Mg as the P-type dopant is 1×10 ¹⁶ atoms /cm ³ . In addition, the average concentration of Zn in the region from the P-type sheath layer to a depth of 0.16 μm (1/3 of the total thickness of the active layer 0.48 μm) is 2×10 ¹⁶ atoms/cm ³ , and the average concentration of Mg is 0.5× 10 ¹⁶ atoms/cm ³ (Total average concentration: 2.5×10 ¹⁶ atoms/cm ³ ). In addition, the average concentration of Zn in the region from the position with a depth of 0.16 μm to the position with a depth of 0.32 μm (from 1/3 to 2/3 of the total thickness of 0.48 μm) is 0.5×10 ¹⁶ atoms/cm ³ , and Mg averages The concentration is 0.2×10 ¹⁶ atoms/cm ³ (total value of average concentration: 0.7×10 ¹⁶ atoms/cm ³ ). The total value of the average concentration of each of Mg and Zn in the subsequent depth (from the depth 2/3 position to the N-type sheath layer) is 0.3×10 ¹⁶ atoms/cm ³ or less. The electrodes are formed on the wafer thus manufactured, the wafer is diced, and then wire bonding is performed to manufacture a light-emitting element.

(Comparative Example 1) The light-emitting element was manufactured as follows. On a GaAs substrate with a 15-degree tilt in the [001] direction, a metal-organic vapor phase epitaxy (MOVPE) method was used to form a light-emitting element wafer with the following layers sequentially stacked: 1.0μm thick (Al _x Ga _{1 － x} ) _y In _{1 － y} P (0≦x≦1, 0.4≦y≦0.6) composed of an etching stop layer; 1.0μm thick N-type sheath layer; 0.9μm thick (Al _x Ga _{1 － x} ) _y In _{1 － y} P (0≦x≦1, 0.4≦y≦0.6) composed of an active layer; composed of (Al _x Ga _{1 － x} ) _y In _{1 － y} P (0≦x≦1 , 0.4 ≦ y P-type layer 1.0μm thick sheath constituted ≦ 0.6); a _{Ga y in 1 - y P (} 0.0 ≦ y ≦ 1.0) consisting of an intermediate layer (buffer layer) is formed; having more than 0.5μm Thickness of GaP current spreading layer (current spreading layer).

The active layer is composed of a uniformly composed (Al _x Ga _{1 - x} ) _y In _{1 - y} P (0≦x≦1, 0.4≦y≦0.6) layer, and is doped by gas (using DEZn, Cp ₂ Mg ) The total value of the respective concentrations of Mg and Zn in the active layer is set to 0.3×10 ¹⁶ atoms/cm ³ or less. The electrodes are formed on the wafer thus manufactured, the wafer is diced, and then wire bonding is performed to manufacture a light-emitting element.

(Comparative Example 2) The light-emitting element was manufactured as follows. On a GaAs substrate with a 15-degree tilt in the [001] direction, a metal-organic vapor phase epitaxy (MOVPE) method was used to form a light-emitting element wafer with the following layers sequentially stacked: 1.0μm thick (Al _x Ga _{1 － x} ) _y In _{1 － y} P (0≦x≦1, 0.4≦y≦0.6) composed of an etching stop layer; 1.0μm thick N-type sheath layer; 0.9μm thick (Al _x Ga _{1 － x} ) _y In _{1 － y} P (0≦x≦1, 0.4≦y≦0.6) composed of an active layer; composed of (Al _x Ga _{1 － x} ) _y In _{1 － y} P (0≦x≦1 , 0.4 ≦ y P-type layer 1.0μm thick sheath constituted ≦ 0.6); a _{Ga y in 1 - y P (} 0.0 ≦ y ≦ 1.0) consisting of an intermediate layer (buffer layer) is formed; having more than 0.5μm Thickness of GaP current spreading layer (current spreading layer).

The active layer is composed of a uniformly composed (Al _x Ga _{1 - x} ) _y In _{1 - y} P (0≦x≦1, 0.4≦y≦0.6) layer, and is doped by gas (using DEZn, Cp ₂ Mg) The concentration of Zn in the active layer is fixed to 5×10 ¹⁶ atoms/cm ³ , and the concentration of Mg is fixed to 1×10 ¹⁶ atoms/cm ³ (total concentration value: 6×10 ¹⁶ atoms/cm ³ ). The electrodes are formed on the wafer thus manufactured, the wafer is diced, and then wire bonding is performed to manufacture a light-emitting element.

Table 2 shows the light output ratio and lifetime characteristics of the light-emitting elements of Example 1, Example 2, Comparative Example 1, and Comparative Example 2 due to different ambient temperatures (0° C. vs. 60° C.). As shown in Table 2, regarding Examples 1 and 2, the light output ratio due to the difference in ambient temperature is 0.86 or more, and the lifetime characteristic is 87, both of which are good values. On the other hand, in Comparative Example 1, since there are almost no dopants in the active layer, the lifetime characteristics are good, but the light output ratio due to different environmental temperatures is 0.8, and the brightness change due to the environmental temperature is large. In addition, in Comparative Example 2, the light output ratio due to the difference in ambient temperature was good, but the dopant of the active layer did not gradually decrease but was fixed, and the lifetime characteristic was 60% and deteriorated.

【Table 2】 Relative light output ratio (0℃vs60℃) Life characteristics (%) Example 1 0.86 87 Example 2 0.87 87 Comparative example 1 0.8 89 Comparative example 2 0.87 60

In addition, the inventor of the present case has confirmed that, in addition to Examples 1 and 2 using gas doping, after forming at least the P-type sheath layer, heat treatment is applied to diffuse the P-type dopant from the P-type sheath layer to The active layer can produce a light-emitting element having the same gradient doping concentration profile as in Examples 1 and 2, and having the same light output ratio and lifetime characteristics.

In addition, this invention is not limited to the said embodiment. The above-mentioned embodiments are exemplified, and the technical ideas described in the scope of the patent application of the present invention have substantially the same constitution and exert the same effects are included in the technical scope of the present invention.

100: GaAs starting substrate 102: AlInP etching stop layer 103: N-type AlGaInP sheath layer 104: AlGaInP active layer 105: P-type AlGaInP sheath layer 106: P-type InGaP buffer layer 107: P-type GaP current propagation layer 110: Light-emitting element 200: GaAs starting substrate 202: AlInP etching stop layer 203: N-type AlGaInP sheath layer 204: AlGaInP active layer 205: P-type AlGaInP sheath layer 206: P-type InGaP buffer layer 207: P-type GaP current propagation layer 210: light-emitting element 300: GaAs starting substrate 302: AlInP etching stop layer 303: N-type AlGaInP sheath layer 304: AlGaInP active layer 305: P-type AlGaInP sheath layer 306: P-type InGaP buffer layer 307: P-type GaP current propagation layer 310: Light-emitting element

Fig. 1 is a schematic diagram showing an example of the light-emitting device of the present invention. Fig. 2 is an explanatory diagram showing the average P-type dopant concentration in the active layer. Fig. 3 is a schematic diagram showing another example of the light-emitting device of the present invention. Fig. 4 is a schematic diagram showing an example of a conventional light-emitting device.

103: N-type AlGaInP sheath layer

104: AlGaInP active layer

105: P-type AlGaInP sheath layer

Claims (13)

A light-emitting element includes a light-emitting part having an N-type sheath layer, an active layer, and a P-type sheath layer sequentially formed, wherein the active layer includes: P-type dopants whose concentration is derived from the P-type sheath The layer side gradually decreases toward the N-type sheath layer side; and in the active layer, the average P-type doping in the region from the P-type sheath layer to the position of 1/3 of the thickness of the active layer The substance concentration is 1.0×10 ¹⁶ atoms/cm ³ or more and 3.0×10 ¹⁷ atoms/cm ³ or less. Such as the light-emitting element of claim 1, wherein The light-emitting part is composed of an AlGaInP-based compound semiconductor. The light-emitting element of claim 1, wherein, in the active layer, the average value of the area from the position of 1/3 of the thickness of the active layer to the position of 2/3 of the thickness of the active layer from the P-type sheath layer is the P The concentration of the type dopant is 0.3×10 ¹⁶ atoms/cm ³ or more and 3.0×10 ¹⁶ atoms/cm ³ or less. The light-emitting element of claim 2, wherein, in the active layer, the average value of the area from the position of 1/3 of the thickness of the active layer to the position of 2/3 of the thickness of the active layer is the P The concentration of the type dopant is 0.3×10 ¹⁶ atoms/cm ³ or more and 3.0×10 ¹⁶ atoms/cm ³ or less. Such as the light-emitting element of claim 3 or claim 4, wherein, in the active layer, the average of the area from the position of 2/3 of the thickness of the active layer to the N-type sheath layer from the P-type sheath layer The P-type dopant concentration is 0.3×10 ¹⁶ atoms/cm ³ or less. A method for manufacturing a light-emitting element, the light-emitting element includes a light-emitting portion formed with an N-type sheath layer, an active layer, and a P-type sheath layer in sequence, characterized by doping with P-type dopants to manufacture the light-emitting element as follows Situation: In the active layer, the P-type dopant concentration gradually decreases from the P-type sheath layer side to the N-type sheath layer side, and in the active layer, from the P-type sheath layer to the The average P-type dopant concentration in the region up to the position 1/3 of the thickness of the active layer is 1.0×10 ¹⁶ atoms/cm ³ or more and 3.0×10 ¹⁷ atoms/cm ³ or less. Such as the method of manufacturing a light-emitting element of claim 6, wherein: The light-emitting part is composed of an AlGaInP-based compound semiconductor. The method of manufacturing a light-emitting element of claim 6, wherein when the P-type dopant is doped in the active layer, the doping is as follows: In the active layer, the P-type sheath layer The average P-type dopant concentration in the region from the position of 1/3 thickness of the active layer to the position of 2/3 thickness is 0.3×10 ¹⁶ atoms/cm ³ or more and 3.0×10 ¹⁶ atoms/cm ³ or less. The method for manufacturing a light-emitting element of claim 7, wherein when the P-type dopant is doped into the active layer, the doping is as follows: In the active layer, the P-type sheath layer The average P-type dopant concentration in the region from the position of 1/3 thickness of the active layer to the position of 2/3 thickness is 0.3×10 ¹⁶ atoms/cm ³ or more and 3.0×10 ¹⁶ atoms/cm ³ or less. The method for manufacturing a light-emitting element according to claim 8, wherein, when the P-type dopant is doped into the active layer, the doping is as follows: In the active layer, the P-type sheath layer The average P-type dopant concentration in the region from the position of 2/3 of the thickness of the active layer to the N-type sheath layer is 0.3×10 ¹⁶ atoms/cm ³ or less. The method for manufacturing a light-emitting element according to claim 9, wherein when the P-type dopant is doped into the active layer, the doping is as follows: In the active layer, the P-type sheath layer The average P-type dopant concentration in the region from the position of 2/3 of the thickness of the active layer to the N-type sheath layer is 0.3×10 ¹⁶ atoms/cm ³ or less. Such as the method of manufacturing a light-emitting element of any one of claim 6 to claim 11, wherein: The doping of the P-type dopant to the active layer is performed in the following manner: Gas doping is performed while forming the active layer. Such as the method of manufacturing a light-emitting element of any one of claim 6 to claim 11, wherein: The doping of the P-type dopant to the active layer is performed in the following manner: After the active layer is formed, the P-type sheath layer doped with the P-type dopant is formed, and then heat treatment is applied to diffuse the P-type dopant that has been doped into the P-type sheath layer to The active layer.

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