JP2012129388A - Semiconductor light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase reliability of a semiconductor light-emitting device.SOLUTION: The semiconductor light-emitting device comprises: an n-type clad layer of AlGaInP; a luminous layer of undoped AlGaInP formed on the n-type clad layer; a p-type clad layer of Mg-added AlGaInP formed on the luminous layer; and a current diffusion layer of Zn-added p-type GaInP formed on the p-type clad layer.

Description

    The present invention relates to a semiconductor light emitting device.

  Generally, a semiconductor light emitting device (LED) is manufactured by epitaxially growing a desired crystal on a compound semiconductor substrate. In the case of an AlGaInP-based LED, a GaAs crystal is often used for the substrate (see, for example, Patent Document 1).

  FIG. 17 is a schematic cross-sectional view of a semiconductor light emitting device (LED) 500 having a double hetero structure according to a conventional example. The semiconductor light emitting device (LED) includes an n-type GaAs substrate 51, an n-type first cladding layer 52, an undoped active layer 53, a p-type second cladding layer 54, a p-type current diffusion layer 55, a p-side electrode. A (first electrode) 56 and an n-side electrode (second electrode) 57 are included.

On the n-type GaAs substrate 51, a first cladding layer 52 having a first conductivity type (for example, n-type) and a band gap larger than that of the active layer 53 is formed by MOCVD. The first cladding layer 52 is made of, for example, an n-type (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P crystal and has a band gap of 2.3 eV.

On the first clad layer 52, an active layer (light emitting layer) 53 that emits light of a desired wavelength is formed. The active layer 53 is made of, for example, an undoped (Al _0.1 Ga _0.9 ) _0.5 In _0.5 P crystal, and emits red light with a band gap of 1.9 eV. The active layer 53 may have a quantum well structure (QW) having a well layer and a barrier layer made of an AlGaInP-based compound semiconductor.

On the active layer 53, a second cladding layer 54 having a second conductivity type (for example, p-type) and a band gap larger than that of the light emitting layer is formed. The second cladding layer 54 is made of, for example, p-type (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P crystal and has a band gap of 2.3 eV.

  A p-type current diffusion layer 55 is formed on the second cladding layer 54 as necessary. The p-type current diffusion layer 55 is made of, for example, a p-type GaP crystal and has a band gap of 2.25 eV.

  In order to supply a current, a p-side electrode 56 is formed on a partial region of the upper surface of the p-type current diffusion layer 55 (the second cladding layer 54 when the p-type current diffusion layer 55 is not formed). An n-side electrode 57 is formed on the lower surface of the GaAs substrate 51.

  Aiming to further increase the brightness of the LED 50, the GaAs substrate 51 used for growth, which is an absorption layer, is removed and bonded to a transparent substrate, or a reflective substrate having a reflective structure is bonded to a permanent substrate such as Si. Thus, a structure with increased brightness is known (see, for example, Patent Document 2 and Patent Document 3). This increase in brightness has further expanded the LED market.

Japanese Patent Laid-Open No. 11-121796 JP 2009-4487 A JP 2010-50318 A

  Recently, the demand for reliability is increasing as the LED market expands. In particular, the luminous intensity degradation due to energization is considered to be largely caused by the diffusion of p-type impurities into the active layer.

  As a countermeasure, a method of inserting an undoped layer between the active layer and the p-type cladding layer is known. Although the diffusion into the active layer is suppressed by inserting the undoped layer, the carrier injection from the p-type cladding layer is reduced, so the efficiency is reduced in the large current region, and the linearity between the current and the optical output is reduced. There is no sex.

  A method is also known in which Mg having a smaller diffusion coefficient than Zn is used as an impurity in the p-type cladding layer and the current diffusion layer. Mg as a p-type impurity has good doping efficiency, but has problems such as a large doping delay (the time from the start of supply until it is actually taken in) and a large effect (memory effect) remaining in the growth reactor. It is a difficult material to handle.

  An object of the present invention is to improve the reliability of a semiconductor light emitting device.

  Another object of the present invention is to improve linearity between current and light output of a semiconductor light emitting device.

  According to one aspect of the present invention, a semiconductor light emitting device is formed on an n-type cladding layer made of AlGaInP, a light emitting layer made of undoped AlGaInP, and formed on the light emitting layer. A p-type cladding layer made of AlGaInP to which Mg is added; and a current diffusion layer made of p-type GaInP to which Zn is added and formed on the p-type cladding layer.

  According to the present invention, the reliability of the semiconductor light emitting device can be improved.

  Further, according to the present invention, the linearity between the current and the optical output of the semiconductor light emitting device can be improved.

1 is a schematic cross-sectional view of a semiconductor light emitting device 101 according to an embodiment of the present invention. It is a graph showing the SIMS analysis result of the n-type clad layer 2, the light emitting layer 3, and the p-type clad layer 4 of the semiconductor light-emitting device 101 by the Example of this invention. It is a schematic sectional drawing of the semiconductor light-emitting device 111 by the 1st comparative example (comparative example 1). 6 is a graph showing SIMS analysis results of an n-type cladding layer 2, a light-emitting layer 3, and a p-type cladding layer 64 of a semiconductor light emitting device 111 according to Comparative Example 1. 10 is a graph showing a SIMS analysis result of a semiconductor light emitting device 111 according to a modification of Comparative Example 1. It is a graph which shows the change of the light emission output at the time of electricity supply. It is a schematic sectional drawing of the semiconductor light-emitting device 121 by the 2nd comparative example (comparative example 2). It is a graph showing the SIMS analysis result of the semiconductor light-emitting device 121 by the comparative example 2 of the production 1st time and the production continuous 3rd time. It is a schematic sectional drawing of the semiconductor light-emitting device 131 by the 3rd comparative example (comparative example 3). 14 is a graph showing SIMS analysis results of an n-type cladding layer 2, a light-emitting layer 3, and a p-type cladding layer 84 of a semiconductor light emitting device 131 according to Comparative Example 3. 1 is a schematic cross-sectional view of an LED device structure 100 according to an embodiment of the present invention. 1 is a schematic cross-sectional view for explaining a method of manufacturing an LED device structure 100 according to an embodiment of the present invention. 1 is a schematic cross-sectional view for explaining a method of manufacturing an LED device structure 100 according to an embodiment of the present invention. 3 is a graph showing current-voltage characteristics of an LED device structure 100 according to an embodiment of the present invention and an LED device structure according to Comparative Example 1; It is a graph which shows the electric current-light output characteristic of the LED device structure using the comparative example 1 and its modification. It is the table | surface which compared the p-type cladding layer and current spreading layer of the Example of this invention, and Comparative Examples 1-3. It is a schematic sectional drawing of the semiconductor light-emitting device (LED) 50 of the double hetero structure by a prior art example.

  FIG. 1 is a schematic cross-sectional view of a semiconductor light emitting device 101 according to an embodiment of the present invention.

  The semiconductor light emitting device 101 includes an n-type GaAs substrate 1, an n-type cladding layer 2, a light-emitting layer 3, a p-type cladding layer 4, a p-type current diffusion layer 5, a p-side electrode (first electrode) 6, And an n-side electrode (second electrode) 7.

The n-type cladding layer 2 is disposed on the n-type GaAs substrate 1 and doped with Si as an n-type impurity (Al _y Ga _1-y ) _x In _1-x P (0.45 ≦ x ≦ 0.55, 0.3 ≦ y ≦ 1). In this embodiment, for example, it is an n-type (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P layer, the film thickness is about 3 μm, and the carrier concentration is 1 × 10 ¹⁸ cm ⁻³ .

The light emitting layer 3 is formed on the n-type cladding layer 2 and is undoped (Al _y1 Ga _1-y1 ) _x In _1-x P (0.4 ≦ x ≦ 0.6, 0 ≦ y1 ≦ 0.7). Quantum well structure comprising a well layer made of and a barrier layer made of undoped (Al _y2 Ga _1-y2 ) _x In _1-x P (0.4 ≦ x ≦ 0.6, 0 ≦ y2 ≦ 0.7) (Where y2> y1). Alternatively, a bulk active layer made of undoped (Al _y Ga _1-y ) _x In _1-x P (0.4 ≦ x ≦ 0.6, 0 ≦ y ≦ 0.7) may be used as the light emitting layer 3. In this embodiment, for example, a well layer made of (Al _0.1 Ga _0.9 ) _0.5 In _0.5 P with a thickness of 10 nm and (Al _0.5 Ga _0.5 ) ₀ with a thickness of 10 nm. _{It is} a quantum well (QW) structure in which a barrier layer made of _0.5 In _0.5 P is repeated 20 cycles.

The p-type cladding layer 4 is formed on the light emitting layer 3 and (Al _y Ga _1-y ) _x In _1-x P (0.45 ≦ x ≦ 0.55, 0.3 ≦ 3) to which Mg is intentionally added. y ≦ 1), and the carrier concentration is in the range of 1 × 10 ¹⁷ to 1 × 10 ¹⁸ cm ⁻³ . In this embodiment, for example, it is made of (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P, the film thickness is about 1 μm, and the carrier concentration is 2 × 10 ¹⁷ cm ⁻³ .

The p-type current spreading layer 5 is a p-type Ga _1-z In _z P (0 ≦ z ≦ 0.1) layer that is disposed on the p-type cladding layer 4 and intentionally added with Zn, and has a Zn dopant concentration. Is in the range of 3 × 10 ¹⁸ to 1 × 10 ¹⁹ cm ⁻³ . In this embodiment, for example, it is made of GaP, the film thickness is about 1 μm, and the Zn dopant concentration is 3 × 10 ¹⁸ cm ⁻³ . The p-type cladding layer 4 contains Zn diffused from the p-type current diffusion layer 5. The Zn dopant concentration by the diffusion of the p-type cladding layer 4 is in the range of 5 × 10 ^{16 to} 5 × 10 ¹⁷ cm ⁻³ .

  The n-type GaAs substrate 1, the n-type cladding layer 2, the light emitting layer 3, the p-type cladding layer 4 and the p-type current diffusion layer 5 are prepared by a well-known MOCVD method, phosphine as a raw material, and an organometallic material TMG as a group III raw material. (Trimethylgallium), TMA (trimethylaluminum), and TMI (trimethylindium) were used.

Silane (SiH ₄ ) as a dopant for forming the n-type cladding layer 2, dicyclopentamagnesium (Cp ₂ Mg) as a dopant for forming the p-type cladding layer 4, and as a dopant for forming the p-type current diffusion layer 5 Dimethyl zinc (DMZn) was used.

  Hydrogen was used as the carrier gas, the V / III ratio was 30 to 200, the growth temperature of the AlGaInP layer was 670 ° C., the growth temperature of the GaP layer was 770 ° C., and the semiconductor light emitting device 101 was manufactured under a reduced pressure of 10 kPa.

  In order to supply current, a p-side electrode (first electrode) 6 is formed on a part of the upper surface of the p-type current diffusion layer 5, and an n-side electrode (second electrode) is formed on the lower surface of the GaAs substrate 1. 7) was formed, and dicing was performed to 200 μm square. It was mounted on a TO-46S stem and an Au wire was attached. When a current of 20 mA was passed through this, the light output was 1.0 mW and the voltage applied to the semiconductor light emitting device was 1.95V.

  FIG. 2 is a graph showing SIMS (Secondary Ionomic Probe Mass Spectrometer) analysis results of the n-type cladding layer 2, the light-emitting layer 3, and the p-type cladding layer 4 of the semiconductor light emitting device 101 according to the embodiment of the present invention.

  In this example, Zn is not intentionally added to the p-type cladding layer 4, but it can be seen that Zn is detected. Zn in the p-type cladding layer 4 is due to diffusion from the p-type current diffusion layer (Zn—GaP layer) 5 to which Zn is intentionally added.

  In order to spread the current uniformly, high concentration doping of Zn into the p-type current diffusion layer (Zn—GaP layer) 5 is necessary. As described above, the GaP layer has a fabrication temperature of about 770 ° C. and AlGaInP. Since it is about 100 ° C. higher than the 670 ° C., which is the layer manufacturing temperature, Zn diffuses. However, in this embodiment, since the p-type cladding layer 4 is not intentionally doped with Zn, the light emitting layer 3 hardly diffuses Zn.

When the p-type current diffusion layer 5 is doped with Mg, the same effect of remaining Mg as in the second comparative example (comparative example 2) described later occurs. This is because the p-type current diffusion layer 5 needs to have a higher carrier concentration in order to allow the current to flow uniformly and to make good contact with the electrode, and needs to be doped with a larger amount of Mg than the p-type cladding layer 4. Because there is. However, in this embodiment, only the p-type cladding layer 4 is doped with Mg, and the p-type current diffusion layer 5 is doped with Zn. In addition, since the Mg doping amount to the p-type cladding layer 4 is 1 × 10 ¹⁸ cm ⁻³ or less, there is no influence of the residual.

  FIG. 3 is a schematic cross-sectional view of the semiconductor light emitting device 111 according to the first comparative example (Comparative Example 1). The semiconductor light emitting device 101 according to the embodiment shown in FIG. Since other configurations are the same as those in the embodiment, the same reference numerals are given and description thereof is omitted.

The p-type cladding layer 64 of the semiconductor light emitting device 111 is made of (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P intentionally added with Zn, for example, having a film thickness of about 1 μm and a Zn dopant. The concentration is 2 × 10 ¹⁷ cm ⁻³ .

  FIG. 4 is a graph showing SIMS analysis results of the n-type cladding layer 2, the light-emitting layer 3, and the p-type cladding layer 64 of the semiconductor light emitting device 111 according to Comparative Example 1.

  In order to spread the current uniformly, the current diffusion layer (Zn—GaP layer) 5 needs to be doped with Zn at a high concentration, and the p-type current diffusion layer 5 has a higher fabrication temperature than AlGaInP (+ 100 ° C. or more). Therefore, it can be seen that Zn is diffused in the p-type cladding layer 64 and the light emitting layer 3. Due to the diffused Zn, the light intensity is deteriorated by energization.

  FIG. 5 is a graph showing the SIMS analysis result of the semiconductor light emitting device 111 according to the modification of the first comparative example. In this modification, in order to prevent Zn diffusion into the light emitting layer 3, an undoped AlGaInP layer of 300 nm is formed between the light emitting layer 3 and the p-type cladding layer 64 of the semiconductor light emitting device 111 according to Comparative Example 1 shown in FIG. Inserted with a film thickness of. It can be seen that Zn is not diffused to the light emitting layer 3 by inserting the undoped layer.

  FIG. 6 is a graph showing changes in light emission output during energization. The semiconductor light emitting device 101 according to the example and the semiconductor light emitting device 111 having a structure without an undoped layer doped with only Zn according to the comparative example 1 were subjected to a 20 mA energization test at room temperature.

  In the semiconductor light emitting device 101 according to the example, the light emission output does not change even when the energization time is increased, whereas in the semiconductor light emitting device 111 of the comparative example 1, the light emission output decreases at an early stage. This is considered to be caused by Zn diffused to the light emitting layer 3. In Comparative Example 1, it is considered that the diffused Zn works as a non-light emitting center by energization.

Furthermore, in the semiconductor light emitting device 101 according to the example, the Mg dopant concentration of the p-type cladding layer 4 is 1 × 10 ¹⁸ cm ^−3, and the Zn dopant concentration of the current diffusion layer (GaP layer) 5 is 1 × 10 ¹⁹ cm. ^Even in the case of ⁻³ , there was no Zn diffusion into the light emitting layer 3, and the same effect was confirmed in the current test. Even when the Zn dopant concentration of the current diffusion layer (GaP layer) 5 was 1 × 10 ¹⁹ cm ⁻³ , the same diffusion phenomenon was confirmed when SIMS analysis was performed. Since the Zn dopant concentration in the p-type current diffusion layer 5 is high, the Zn dopant concentration in the p-type cladding layer 4 is 5 × 10 ¹⁷ cm ⁻³ , but light emission of Zn is similar to the semiconductor light emitting device 101 described above. No diffusion into layer 3 was seen. This is presumably because Mg intentionally added in the p-type cladding layer 4 has an effect of stopping Zn diffusion from the p-type current diffusion layer 5 to the light emitting layer 3. Also in this case, it was found that the luminous intensity did not deteriorate due to energization.

FIG. 7 is a schematic cross-sectional view of a semiconductor light emitting device 121 according to a second comparative example (Comparative Example 2). Only the current diffusion layer 75 is different from the semiconductor light emitting device 101 according to the embodiment shown in FIG. Since other configurations are the same as those in the embodiment, the same reference numerals are given and description thereof is omitted. The p-type cladding layer 74 is made of (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P intentionally added with Mg, similarly to the p-type cladding layer 4 of the example. Although the film thickness is about 1 μm and the Mg dopant concentration is 2 × 10 ¹⁷ cm ⁻³ , Zn is not included due to diffusion, and therefore, a reference number different from that of the p-type cladding layer 4 is given.

The current diffusion layer 75 of Comparative Example 2 is made of p-type GaP to which Mg is intentionally added. For example, the film thickness is about 1 μm and the Mg dopant concentration is 3 × 10 ¹⁸ cm ⁻³ . When a current of 20 mA was passed through the semiconductor light emitting device 121, the optical output was 0.2 mW, and the voltage applied to the semiconductor light emitting device was 1.95V.

  Mg has a smaller diffusion coefficient than Zn and is difficult to diffuse to the light emitting layer 3. However, high concentration doping of Mg must be performed in the current diffusion layer 75, and Mg having a large memory effect remains in the reaction furnace. Therefore, as the production of the semiconductor light emitting device 121 is repeated, the residual Mg increases, so that unintended Mg is taken in other than the p-type cladding layer 74 and the current diffusion layer 75.

  FIG. 8 is a graph showing the SIMS analysis results of the semiconductor light emitting device 121 according to Comparative Example 2 in the first fabrication and the third fabrication.

  As is apparent from the figure, Mg was detected only in the p-type cladding layer 74 in the first fabrication, whereas Mg was also detected in the light emitting layer 3 and the n-type cladding layer 2 in the third fabrication. Such unintentionally remaining Mg adversely affects the device characteristics, and as a result, causes a problem that the brightness rapidly decreases.

  FIG. 9 is a schematic cross-sectional view of a semiconductor light emitting device 131 according to a third comparative example (Comparative Example 3). The semiconductor light emitting device 101 according to the embodiment shown in FIG. Since other configurations are the same as those in the embodiment, the same reference numerals are given and description thereof is omitted.

The p-type cladding layer 84 is made of (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P intentionally added with Mg and Zn. For example, the film thickness is about 1 μm, and Mg and Zn dopants. The concentration is 2 × 10 ¹⁷ cm ⁻³ . When a current of 20 mA was passed through the semiconductor light emitting device 131 according to Comparative Example 3, the light output was 0.3 mW and the voltage applied to the semiconductor light emitting device was 1.95V.

  FIG. 10 is a graph showing SIMS analysis results of the n-type cladding layer 2, the light-emitting layer 3, and the p-type cladding layer 84 of the semiconductor light emitting device 131 according to Comparative Example 3.

  Mg and Zn are detected in the p-type cladding layer 84 by simultaneous doping of the p-type cladding layer 84 with Mg and Zn. Since the p-type cladding layer 84 and the p-type current diffusion layer 5 are doped with Zn, Zn is diffused in the crystal. Since Mg has an effect of suppressing Zn diffusion, Zn is not diffused in the light emitting layer 3, but a region having a high Zn dopant concentration exists in the vicinity of the light emitting layer 3 (region having a depth of about 1 μm). The region having a high Zn dopant concentration in the vicinity of the light emitting layer 3 forms a non-light emitting center, and in Comparative Example 3, it is considered that the light emission output rapidly decreases.

  Subsequently, the method described in paragraphs [0012] to [0026] of JP2009-4487A or paragraphs [0013] to [0020] of JP2010-50318A is shown in FIG. The semiconductor light emitting device structure 10 according to the embodiment of the present invention is bonded to a permanent substrate (Si) 11 made of a material different from the GaAs substrate 1 (FIG. 1), the GaAs substrate 1 is removed, and FIG. An electrode device structure 100 was fabricated by arranging the electrodes shown. The produced LED device structure 100 was mounted on a stem, a wire was attached, and a bullet type LED having a diameter of 5 mm was produced from an epoxy resin.

  FIG. 11 is a schematic cross-sectional view of an LED device structure 100 according to an embodiment of the present invention.

The LED device structure 100 includes a first Pt layer (first electrode) 12, a support substrate 11, a second Pt layer 13, a Ti (titanium) layer 14, a bonding (AuSnNi) layer 15, and a first electrode (TaN). Reflective insulation in which a layer 16, a second electrode (TiW) layer 17, a third electrode (TaN) layer 18, a fourth electrode (AuZn) layer 19, and a contact portion (contact layer) 20 are embedded in a plurality of places The (SiO ₂ ) layer 21 and the semiconductor light emitting device structure 10 according to the example are sequentially stacked. In addition, a second electrode 22 made of, for example, Au is formed on the semiconductor light emitting device structure 10.

  Below, with reference to FIGS. 11-13, the manufacturing process of the LED device structure 100 is demonstrated easily.

  First, as shown in FIG. 12, a second Pt layer 13 is formed on the main surface of a support substrate (permanent substrate) 11 made of silicon (Si) to which an n-type impurity is added, and is opposite to the main surface. A first electrode (first Pt layer) 12 is also formed on the bottom surface. The first electrode (first Pt layer) 12 and the second Pt layer 13 are used as ohmic electrodes. The first electrode 12 functions as an electrode for establishing electrical connection with the outside. The Pt layer is formed by, for example, resistance heating vapor deposition, electron beam vapor deposition, sputtering, or the like.

  A Ti layer 14 is formed on the second Pt layer 13. On the Ti layer 14, a first Sn absorption layer 151 made of Ni, an Au layer 152, and a solder layer 153 made of an AuSn alloy are formed. The Ti layer 14 and the first Sn absorption layer 151 are formed by, for example, electron beam evaporation or sputtering, and the Au layer 152 and the solder layer 153 are formed by, for example, resistance heating evaporation or sputtering.

Next, as shown in FIG. 13, the semiconductor light emitting device structure 10 according to the embodiment shown in FIG. 1 is grown on the main surface of the second substrate (temporary substrate) 110 made of semiconductor. Thereafter, on the semiconductor light emitting device structure 10 by a chemical vapor deposition (CVD) method, the reflective insulating layer made of SiO ₂ (SiO ₂ layer) 21 is formed. Thereafter, a resist is applied and patterned on the reflective insulating layer 21, and etching is performed using the patterned resist as a mask to form a plurality of openings in the reflective insulating layer 21. A contact portion 20 made of AuZn is buried by sputtering on the semiconductor light emitting device structure 10 partially exposed by the opening. The contact portion 20 may be deposited by resistance heating vapor deposition or electron beam vapor deposition.

Next, a reflective electrode layer (fourth electrode layer) 19 made of AuZn is formed on the reflective insulating layer 21 by resistance heating vapor deposition, electron beam vapor deposition, or sputtering. The reflective electrode layer 19 is in ohmic contact with the semiconductor light emitting device structure 10 through the contact portion 20. The reflective electrode layer 19 has a function of efficiently reflecting light incident from the semiconductor light emitting device structure 10 at the interface with the reflective insulating layer (SiO ₂ layer) 21.

  Further, a third electrode (TaN) layer 18 made of TaN is formed on the reflective electrode layer 19 by reactive sputtering, and then, for example, heat treatment is performed at about 500 ° C. in a nitrogen atmosphere. By this heat treatment, the reflective electrode layer 19 (contact portion 20) made of AuZn and the surface layer portion of the semiconductor light emitting device structure 10 made of p-type AlGaInP are alloyed, and good ohmic contact is obtained.

  Next, the second electrode layer 17 made of TiW (titanium-tungsten alloy) and the first electrode layer 16 made of TaN (tantalum nitride) are formed on the third electrode (TaN) layer 18 by reactive sputtering. To do. The first electrode layer 16 made of TaN (tantalum nitride), the second electrode layer 17 made of TiW (titanium-tungsten alloy), and the third electrode layer 18 made of TaN are barrier layers that prevent diffusion of metal atoms. Function as.

  Thereafter, a second Sn absorption layer 154 made of Ni is formed on the TaN layer 16 by electron beam evaporation or sputtering. An Au layer 155 is formed on the second Sn absorption layer 154 by resistance heating vapor deposition or sputtering.

  Next, the support substrate (permanent substrate) 11 shown in FIG. 12 and the temporary substrate 110 shown in FIG. 13 are arranged so that their main surfaces face each other, and the AuSn solder layer 153 on the support substrate 11 side, The Au layer 155 on the substrate 110 side is brought into close contact, and thermocompression bonding is performed in a nitrogen atmosphere.

  As shown in FIG. 11, the AuSn solder layer 153 is melted, the Au of the Au layers 152 and 155, the Ni of the first Sn absorption layer 151 and the second Sn absorption layer 154 are melted into the melted solder layer 153. When dissolved, Au and Sn in the Au layers 152 and 155 and the solder layer 153 are diffused and absorbed in the first Sn absorption layer 151 and the second Sn absorption layer 154. When the molten solder layer 153 is solidified, the bonding layer 15 made of AuSnNi is formed. After bonding, the temporary substrate 110 is removed. When the temporary substrate 110 is made of GaAs, for example, it can be removed by wet etching using a mixed solution of ammonia water and hydrogen peroxide solution. In addition to wet etching, removal by dry etching, chemical mechanical polishing (CMP), mechanical grinding, or the like is also possible.

  Finally, the second electrode 22 made of Au is formed by resistance heating vapor deposition, electron beam vapor deposition, sputtering, or the like on a partial region of the surface of the semiconductor light emitting device structure 10 exposed by removing the temporary substrate 110. And formed by a lift-off method. After the second electrode 22 is formed, for example, heat treatment is performed at about 400 ° C. in a nitrogen atmosphere to ensure ohmic contact.

  When the current-light output characteristics of the LED device structure 100 according to the example fabricated as described above were evaluated, it was confirmed that the linearity was good even in a current range of 50 mA.

  Further, an LED device structure was fabricated using a semiconductor light emitting device structure 60 according to Comparative Example 1 shown in FIG. 3 instead of the semiconductor light emitting device structure 10 according to the embodiment of the present invention. The manufactured LED device structure according to Comparative Example 1 was mounted on a stem, a wire was mounted, and a bullet-type LED having a diameter of 5 mm was manufactured using an epoxy resin. Moreover, the LED device structure was similarly produced using the modification of the comparative example 1 which inserted the undoped layer in the semiconductor light-emitting device structure 60 by the comparative example 1. FIG.

  FIG. 14 is a graph showing current-voltage characteristics of the LED device structure 100 according to the embodiment of the present invention and the LED device structure according to the comparative example 1.

  It has been found that the LED device structure 100 according to the example of the present invention has a low voltage value (low resistance value) and high efficiency even at the same current value as compared with the LED device structure according to Comparative Example 1. This is because Zn and Mg are contained in the p-type cladding layer 4 of the example, and the efficiency is poor when only Zn is contained in the p-type cladding layer 64 as in Comparative Example 1. Is shown. When a test similar to the energization test shown in FIG. 6 described above was performed, no deterioration in luminous intensity due to energization was observed in the LED device structure 100 according to the example.

  FIG. 15 is a graph showing the current-light output characteristics of the LED device structure using Comparative Example 1 and its modification.

  The LED device structure using the modified example of Comparative Example 1 in which an undoped layer is inserted has linearity in the low current region (50 mA or less), whereas the light output is rapidly increased in the high current region (50 mA or more). It turns out that it decreases.

  On the other hand, in the LED device structure using Comparative Example 1 without an undoped layer, it can be seen that the linearity between the current and the light output is maintained even in the high current region. In the modified example of the comparative example 1, it is considered that the carrier injection efficiency into the light emitting layer 3 is deteriorated by inserting the undoped layer. In the Zn diffusion suppression by the undoped layer, Zn diffusing into the light emitting layer 3 is suppressed, but it has been found that the linearity of the current-light output characteristics deteriorates.

  FIG. 16 is a table comparing the p-type cladding layer and the current diffusion layer of the example of the present invention and Comparative Examples 1 to 3.

In Comparative Example 1, since Zn was intentionally added to the p-type cladding layer 64 in the structure shown in FIG. 3, the Zn dopant concentration was 1 × 10 ¹⁷ to 1 × 10 ¹⁸ cm ^−3, and Zn was very Zn diffuses into the light emitting layer 3. Therefore, although the light emission efficiency is high and there is no influence of residual Mg, the reliability is low and the current-voltage characteristics are not good.

In Comparative Example 2, in the structure shown in FIG. 7, Mg was intentionally added to the current diffusion layer 75 to set the Mg dopant concentration to 3 × 10 ¹⁸ to 1 × 10 ¹⁹ cm ⁻³ . Since Mg is difficult to diffuse, it does not diffuse to the light emitting layer 3, but Mg having a large memory effect remains in the reaction furnace, and Mg is detected also in the light emitting layer 3 and the n-type cladding layer 2 when the fabrication is repeated. End up. Therefore, the luminous efficiency is low and there is an influence of Mg residue.

In Comparative Example 3, in the structure shown in FIG. 9, Mg and Zn are simultaneously doped into the p-type cladding layer 84, and the dopant concentration is set to 1 × 10 ¹⁷ to 1 × 10 ¹⁸ cm ⁻³ . Since Mg has an effect of suppressing Zn diffusion, Zn is not diffused in the light emitting layer 3, but a region having a high Zn dopant concentration exists in the vicinity of the light emitting layer 3. Therefore, although there is no influence of residual Mg, the light emission efficiency is low.

In contrast to the above comparative examples 1 to 3, in the embodiment of the present invention, the Mg dopant concentration of the p-type cladding layer 4 is 1 × 10 ¹⁷ to 1 × 10 ¹⁸ cm ⁻³ , p-type in the structure shown in FIG. The Zn dopant concentration of the current spreading layer 5 was 3 × 10 ¹⁸ to 1 × 10 ¹⁹ cm ⁻³ . Thereby, the Zn dopant concentration diffused in the p-type cladding layer 4 could be 5 × 10 ^{16 to} 5 × 10 ¹⁷ cm ^−3, and the diffusion of Zn into the light emitting layer 3 could be prevented. By adopting such a structure, it is possible to manufacture the semiconductor light emitting device 101 with high reliability, good current-voltage characteristics, high light emission efficiency, and no influence of residual Mg.

  In the above-described embodiment, the AlGaInP layer is used for the cladding layers 2 and 4 and the light emitting layer 3, but they are manufactured under conditions matching the GaAs substrate 1. The conditions for matching the GaAs substrate 1 vary depending on the growth temperature.

To match the GaAs substrate 1 _may be adjusted to a value of _{(Al y Ga 1-y)} x In 1-x P of x. When the temperature grows in the range of 500 ° C. to 700 ° C., the range of the value of x in (Al _y Ga _1-y ) _x In _1-x P is 0.45 ≦ x ≦ 0.55. Even in this range, the effect obtained is not changed by controlling the carrier concentration and thickness obtained in the examples.

The active layer 3 (active layer and barrier layer having a quantum well structure) 3 does not need to be matched with the GaAs substrate 1 as long as the thickness is equal to or less than the critical film thickness, and may not be in this range. A preferable range of the composition of the well layer and the barrier layer is (Al _y Ga _1-y ) _x In _1-x P (0.4 ≦ x ≦ 0.6, 0 ≦ y ≦ 0.7 in consideration of the critical film thickness. ).

In the above embodiment, (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P having an Al composition of 70% is used as the n-type cladding layer 2. As long as it is transparent to the light emitting layer 3, the Ga composition is 0%, that is, even if Al _0.5 In _0.5 P is used as the n-type cladding layer 2, the carrier concentration and thickness are controlled according to the embodiment. Just do it. In other words, even in the range of Al composition y in the (Al _y Ga _1-y ) _x In _1-x P (0.45 ≦ x ≦ 0.55, 0.3 ≦ y ≦ 1) cladding, the light emitting layer 3 As long as it is transparent to the surface.

Further, the n-clad structure is a structure having a plurality of Al compositions, for example, (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P with a thickness of 2500 nm and a thickness of 500 nm from the GaAs substrate 1 side ( Even if Al _0.5 Ga _0.5 ) _0.5 In _0.5 P is used, it is sufficient to control the carrier concentration according to the embodiment, and the obtained effect does not change.

In the above-described embodiment, silane (SiH ₄ ) is used as a dopant in order to obtain n-type conductivity. However, even if diethyl tellurium (DeTe) or hydrogen selenide (H ₂ Se) is used, The effect of the invention does not change depending on the n-type impurity, does not depend on the type of impurity in the n-type layer, and the obtained effect does not change. Further, the thickness of the n-type cladding layer 2 does not affect the present invention and is not limited to 3 μm.

  Moreover, although the quantum well structure (Al composition 10%) which emits red light is shown in the above-described embodiment, the p-type cladding layer 4 and the p-type current diffusion layer can be used even if the thickness and the number of periods of the quantum well structure are changed. If the structure of 5 is made the same as the embodiment of the present invention, the same effect can be obtained. The light emitting layer 3 is not limited to the quantum well structure, and may have a homo pn junction structure, a double hetero structure, or a single hetero structure.

  The same applies to the Al composition of the quantum well layer, and the effects of the embodiments can be obtained even when the Al composition is changed to provide a yellow light emitting (590 nm) element or a crimson light emitting element (660 nm). The same applies to the off-angle of the substrate, and the effect does not change even if a GaAs substrate having a different off-angle and off-direction is used. In the embodiment, the n-type GaAs substrate 1 turned off by 15 degrees from (100) is used, but the same effect is confirmed also in the n-type GaAs substrate turned off by 4 degrees from (100).

  In the above embodiment, GaP is used as the p-type current diffusion layer 5, but the p-type current diffusion layer 5 is transparent to the light emitting layer 3 even when InGa (In) is added to form InGaP. It does not affect the effect of the embodiment.

  In addition, the embodiment of the present invention is not limited to a type of LED directly manufactured on a semiconductor substrate, but is not limited to a semiconductor substrate such as GaP, but a light emitting device of a type that is bonded to another permanent substrate (for example, silicon, copper, glass). Also effective. The electrode structure may be any structure as long as a current is injected into the active layer through a pn junction, and there is no need to dispose electrodes on the upper and lower sides. For example, a flip chip type structure may be used.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

1, 51 n-type GaAs substrate 2, 52 n-type cladding layer (first cladding layer)
3, 53 Active layers 4, 54, 64, 74, 84 p-type cladding layer (second cladding layer)
5, 55, 75 Current diffusion layer 6, 56 p-side electrode (first electrode)
7, 57 n-side electrode (second electrode)
10, 60, 70, 80 Semiconductor light emitting device structure 11 Support substrate 12 First electrode 13 Second Pt layer 14 Ti (titanium) layer 15 Bonding layer 16 First electrode layer 17 Second electrode layer 18 Third electrode Layer 19 Fourth electrode layer 20 Contact portion (contact layer)
21 Reflective insulating layer 22 Second electrode 100 LED device structure 101, 111, 121, 131, 500 Semiconductor light emitting device 110 Second substrate (temporary substrate)
151 First Sn absorption layer 152 Au layer 153 Solder layer 154 Second Sn absorption layer 155 Au layer

Claims (5)

An n-type cladding layer made of AlGaInP;
A light emitting layer formed on the n-type cladding layer and made of undoped AlGaInP;
A p-type cladding layer formed on the light emitting layer and made of AlGaInP doped with Mg;
A semiconductor light emitting device having a current diffusion layer formed on the p-type cladding layer and made of p-type GaInP doped with Zn. The p-type cladding layer is made of (Al _y Ga _1-y ) _x In _1-x P (0.45 ≦ x ≦ 0.55, 0.3 ≦ y ≦ 1) to which Mg is added, and the current diffusion The semiconductor light emitting device according to claim 1, comprising Zn diffused from the layer and having a carrier concentration in the range of 1 × 10 ¹⁷ to 1 × 10 ¹⁸ cm ⁻³ . 3. The semiconductor light emitting device according to claim 2, wherein a Zn dopant concentration of the p-type cladding layer is in a range of 5 × 10 ^{16 to} 5 × 10 ¹⁷ cm ⁻³ . The light emitting layer includes an active layer made of undoped (Al _y Ga _1-y ) _x In _1-x P (0.4 ≦ x ≦ 0.6, 0 ≦ y ≦ 0.7) and undoped (Al _y either _{Ga 1-y) x in 1} -x P (0.4 ≦ x ≦ 0.6,0 ≦ y ≦ 0.7) is a quantum well structure comprising a barrier layer made of claims 1 to 3 2. The semiconductor light emitting device according to item 1. The light emitting layer is a bulk active layer made of undoped (Al _y Ga _1-y ) _x In _1-x P (0.4 ≦ x ≦ 0.6, 0 ≦ y ≦ 0.7). The semiconductor light-emitting device of any one of -3.

Images