JP3795624B2 - Nitrogen-3 group element compound semiconductor light emitting device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a blue-emitting nitrogen-3 group element compound semiconductor light emitting device.
[0002]
[Prior art]
Conventionally, a blue light emitting diode using a GaN-based compound semiconductor is known. The GaN-based compound semiconductor is attracting attention because it is a direct transition type and has high emission efficiency, and blue light, which is one of the three primary colors of light, is used as the emission color.
[0003]
Recently, it has become clear that p-type GaN can also be obtained by doping Mg and irradiating it with an electron beam. As a result, a GaN light emitting diode having a pn junction has been proposed in place of the conventional junction between an n layer and a semi-insulating layer (i layer).
[0004]
[Problems to be solved by the invention]
However, even with the light emitting diode having the pn junction described above, the light emission luminance is not yet sufficient, and a sufficient lifetime is not obtained.
Accordingly, an object of the present invention is to improve the light emission luminance of a light emitting diode by using a nitrogen-3 group element compound semiconductor (including Al _x Ga _Y In _1-XY N; X = 0, Y = 0, X = Y = 0). And prolonging the device life.
[0005]
[Means for Solving the Problems]
First inventions of the present application, in the light-emitting element consisting of nitrogen -3-group element compound semiconductor, and a high carrier concentration n ⁺ layer made of silicon (Si) is added n-type nitrogen -3-group element compound semiconductor, A low carrier concentration n layer having an impurity concentration of 1 × 10 ¹⁴ / cm ³ or more made of an n-type nitrogen-3 group element compound semiconductor without addition of impurities formed on the p-type layer side of the high carrier concentration n ⁺ layer; , A high carrier concentration p ⁺ layer made of a p-type nitrogen-3 group element compound semiconductor doped with magnesium (Mg), and having a hole concentration of 1 × 10 ¹⁶ / cm ³ or more. ⁺ a layer, first possess a high carrier concentration p ⁺ layer made of a high hole concentration than the high carrier concentration p ⁺ layer second high carrier concentration p ⁺ layer, and the low carrier concentration n layer, the first high carrier concentration p ⁺ between the layers, the nitrogen of the added p-type magnesium (Mg) -3 It consists element compound semiconductor, a low hole concentration than the first high carrier concentration p ⁺ layer, have a low carrier concentration p layer, the hole concentration of the low carrier concentration p layer ^{1 × 10 14 ~1 × 10 16} / cm It is characterized by ³ .
Still another feature is that an electrode made of nickel (Ni) is formed in the second high carrier concentration p ⁺ layer.
[0006]
The second inventions of the present application, in the light-emitting element consisting of nitrogen -3-group element compound semiconductor, an n-type nitrogen -3-group element compound semiconductor, multilayer the electron concentration increases step away from the p-type layer P-type nitrogen to which magnesium (Mg) is added is formed with a high carrier concentration n ⁺ layer and a layer with the lowest carrier concentration is a low carrier concentration n layer. A low carrier concentration p layer composed of a group-3 element compound semiconductor having a hole concentration of 1 × 10 ¹⁴ / cm ³ or more, and magnesium (Mg) formed on the side opposite to the n-type layer side of the p layer were added. A high carrier concentration p ⁺ layer having a hole concentration of 1 × 10 ¹⁶ / cm ³ or more made of a p-type nitrogen-3 group element compound semiconductor, and an electrode made of nickel (Ni) formed in the p ⁺ layer. Yes, and dark hole of the low carrier concentration p-layer Characterized in that the the ^{1 × 10 14 ~1 × 10 16} / cm 3.
Still another feature is that the high carrier concentration p ⁺ layer includes a first high carrier concentration p ⁺ layer having a low hole concentration and a second high carrier concentration p ⁺ having a hole concentration higher than that of the first high carrier concentration p ⁺ layer. The electrode made of nickel (Ni) is formed in the second high carrier concentration p ⁺ layer.
[0007]
Another feature is that the hole concentration of the high carrier concentration p ⁺ layer is 1 × 10 ¹⁶ to 2 × 10 ¹⁹ / cm ³ .
[0008]
Another feature is that the electron concentration of the high carrier concentration n ⁺ layer is 1 × 10 ¹⁶ to 1 × 10 ¹⁹ / cm ³ , and another feature is that the electron concentration of the carrier concentration n layer is 1 × 10 ¹⁴ to 1 × 10 ¹⁶ / cm ³ .
[0009]
The other feature is that the thickness of the carrier concentration p layer is 0.2 to 1 μm, the other feature is that the thickness of the high carrier concentration p ⁺ layer is 0.1 to 0.5 μm, and the other feature is the high carrier concentration n ^+. The thickness of the layer is 2 to 10 μm, and another feature is that the thickness of the low carrier concentration n layer is 0.5 to 2 μm.
[0010]
Further, another feature is characterized and this constituted the high carrier concentration n ⁺ layer in a gallium nitride (GaN).
[0011]
[Action and effect of the invention]
The present invention relates to a high carrier concentration n ⁺ layer made of an n-type nitrogen-3 group element compound semiconductor to which silicon (Si) is added, and no impurity formed on the p-type layer side of the high carrier concentration n ⁺ layer. A structure with an n-layer having a low carrier concentration of an n-type nitrogen-3 group element compound semiconductor having an additive concentration of 1 × 10 ¹⁴ / cm ³ or more, or an n-type nitrogen-3 group element compound semiconductor, With the structure in which the electron concentration is increased in steps away from the p-type layer, the crystallinity is improved, the emission luminance is improved, and a more pure blue color can be obtained. Furthermore, the electron injection efficiency was improved, the drive voltage was lowered, and the light emission luminance was improved. Also, with these configurations, the light emission luminance is 10 mcd, and this light emission luminance is improved twice as compared with the light emission luminance of the conventional pn junction GaN light emitting diode. The light emission lifetime is 10 ⁴ hours, which is 1.5 times the light emission lifetime of the conventional pn junction GaN light emitting diode.
[0012]
【Example】
First embodiment In Fig. 1, a light emitting diode 10 has a sapphire substrate 1, on which a 500Å AlN buffer layer 2 is formed. Of On the buffer layer 2, in turn, a film thickness of about 2.2 [mu] m, the electron concentration of 2 × 10 ¹⁸ / cm high carrier concentration comprising a silicon-doped GaN of ³ n ⁺ layer 3, a thickness of about 1.5 [mu] m, the electron concentration of 1 × A low carrier concentration n layer 4 made of non-doped GaN of 10 ¹⁶ / cm ³ is formed. Further, on the low carrier concentration n-layer 4, a low carrier concentration p layer 51 made of Mg-doped GaN having a film thickness of about 0.5 μm and a hole concentration of 1 × 10 ¹⁶ / cm ³ , a film thickness of about 0.2 μm, and a hole. A high carrier concentration p ⁺ layer 52 having a concentration of 2 × 10 ¹⁷ / cm ³ is formed. An electrode 7 made of nickel connected to the high carrier concentration p ⁺ layer 52 and an electrode 8 made of nickel connected to the high carrier concentration n ⁺ layer 3 are formed. The electrode 8 and the electrode 7 are electrically insulated and separated by the groove 9.
[0013]
Next, a method for manufacturing the light emitting diode 10 having this structure will be described.
The light emitting diode 10 was manufactured by vapor phase growth using a metal organic compound vapor phase growth method (hereinafter referred to as “M0VPE”).
The gases used were NH ₃ , carrier gas H ₂ , trimethylgallium (Ga (CH ₃ ) ₃ ) (hereinafter referred to as “TMG”) and trimethylaluminum (Al (CH ₃ ) ₃ ) (hereinafter referred to as “TMA”). ), Silane (SiH ₄ ), and biscyclopentadienyl magnesium (Mg (C ₅ H ₅ ) ₂ ) (hereinafter referred to as “CP ₂ Mg”).
[0014]
First, a single crystal sapphire substrate 1 having an A surface cleaned by organic cleaning and heat treatment as a main surface is mounted on a susceptor mounted in a reaction chamber of an M0VPE apparatus. Next, the sapphire substrate 1 was vapor-phase etched at a temperature of 1100 ° C. while flowing H ₂ at normal pressure and a flow rate of 2 liter / min into the reaction chamber.
[0015]
Next, the temperature is lowered to 400 ° C., H ₂ is supplied at 20 liter / min, NH ₃ is supplied at 10 liter / min, and TMA is supplied at 1.8 × 10 ⁻⁵ mol / min. The thickness was formed. Next, the temperature of the sapphire substrate 1 is maintained at 1150 ° C., and H ₂ is diluted to 20 liter / min, NH ₃ is 10 liter / min, TMG is 1.7 × 10 ⁻⁴ mol / min, and H ₂ is diluted to 0.86 ppm. Silane (SiH ₄ ) is supplied at a rate of 200 ml / min for 30 minutes, the film thickness is about 2.2 μm, and the electron concentration
To form a 2 × 10 ¹⁸ / cm high carrier concentration n ⁺ layer 3 made of GaN of ^3.
[0016]
Subsequently, the temperature of the sapphire substrate 1 is maintained at 1150 ° C., H ₂ is supplied at 20 liter / minute, NH ₃ is supplied at 10 liter / minute, and TMG is supplied at a rate of 1.7 × 10 ⁻⁴ mole / minute for 20 minutes. A low carrier concentration n-layer 4 made of GaN having a thickness of about 1.5 μm and an electron concentration of 1 × 10 ¹⁶ / cm ³ was formed.
[0017]
Next, sapphire substrate 1 is set to 1150 ° C., H ₂ is 20 liter / min, NH ₃ is 10 liter / min, TMG is 1.7 × 10 ⁻⁴ mol / min, and CP ₂ Mg is 8 × 10 ⁻⁸ mol / min. A low carrier concentration p-layer 51 made of GaN having a thickness of 0.5 μm was formed by supplying at a rate of 7 minutes. In this state, the low carrier concentration p layer 51 is still an insulator having a resistivity of 10 ⁸ Ωcm or more.
[0018]
Next, sapphire substrate 1 is set to 1150 ° C., H ₂ is 20 liter / min, NH ₃ is 10 liter / min, TMG is 1.7 × 10 ⁻⁴ mol / min, and CP ₂ Mg is 3 × 10 ⁻⁷ mol / min. The high carrier concentration p ⁺ layer 52 made of GaN having a film thickness of 0.2 μm was formed by supplying for 3 minutes. In this state, the high carrier concentration p ⁺ layer 52 is still an insulator having a resistivity of 10 ⁸ Ωcm or more.
[0019]
Next, the high carrier concentration p ⁺ layer 52 and the low carrier concentration p layer 51 were uniformly irradiated with an electron beam using a reflection electron beam diffraction apparatus. The electron beam irradiation conditions are an acceleration voltage of 10 KV, a sample current of 1 μA, a beam moving speed of 0.2 mm / sec, a beam diameter of 60 μmφ, and a degree of vacuum of 2.1 × 10 ⁻⁵ Torr. By this electron beam irradiation, the low carrier concentration p layer 51 becomes a p-conduction type semiconductor having a hole concentration of 1 × 10 ¹⁶ / cm ³ and a resistivity of 40 Ωcm, and the high carrier concentration p ⁺ layer 52 has a hole concentration of 2 × 10 ^17. / cm ^3, it was a p conductivity type semiconductor resistivity 2Omucm. In this way, a wafer having a multilayer structure as shown in FIG. 2 was obtained.
[0020]
3 to 7 described below are cross-sectional views showing only one element on the wafer. Actually, processing is performed on a wafer in which this element is continuously repeated, and thereafter, for each element. Disconnected.
[0021]
As shown in FIG. 3, the SiO ₂ layer 11 was formed to a thickness of 2000 mm on the high carrier concentration p ⁺ layer 52 by sputtering. Next, a photoresist 12 was applied on the SiO ₂ layer 11. Then, by photolithography, the electrode forming portion A corresponding to the hole 15 formed so as to reach the high carrier concentration n ⁺ layer 3 on the high carrier concentration p ⁺ layer 52 and the electrode forming portion thereof are divided into the high carrier concentration p ^+. The photoresist in the portion B where the groove 9 for insulating separation from the electrode of the layer 52 was formed was removed.
[0022]
Next, as shown in FIG. 4, the SiO ₂ layer 11 not covered with the photoresist 12 was removed with a hydrofluoric acid etching solution. Next, as shown in FIG. 5, the high carrier concentration p ⁺ layer 52 and the lower carrier concentration p layer 51, the low carrier concentration n layer 4 below the portion not covered with the photoresist 12 and the SiO ₂ layer 11, A part of the upper surface of the high carrier concentration n ⁺ layer 3 was dry-etched by supplying a vacuum degree of 0.04 Torr, high-frequency power of 0.44 W / cm ² and BCl ₃ gas at a rate of 10 ml / min, and then dry-etched with Ar. In this step, a hole 15 for extracting an electrode for the high carrier concentration n ⁺ layer 3 and a groove 9 for insulating separation were formed.
[0023]
Next, as shown in FIG. 6, the SiO ₂ layer 11 remaining on the high carrier concentration p ⁺ layer 52 was removed with hydrofluoric acid. Next, as shown in FIG. 7, the Ni layer 13 was formed on the entire upper surface of the sample by vapor deposition. As a result, the Ni layer 13 electrically connected to the high carrier concentration n ⁺ layer 3 is formed in the hole 15. Then, a photoresist 14 is applied on the Ni layer 13, and a predetermined amount of the photoresist 14 is left by photolithography so that electrode portions for the high carrier concentration n ⁺ layer 3 and the high carrier concentration p ⁺ layer 52 remain. Patterned into shape.
[0024]
Next, as shown in FIG. 7, the exposed portion of the lower Ni layer 13 was etched with a nitric acid-based etchant using the photoresist 14 as a mask. At this time, the Ni layer 13 deposited in the groove 9 for insulation separation is completely removed. Next, the photoresist 14 was removed with acetone, leaving the electrode 8 of the high carrier concentration n ⁺ layer 3 and the electrode 7 of the high carrier concentration p ⁺ layer 52. Thereafter, the wafer processed as described above was cut for each element to obtain a gallium nitride light emitting element having a pn structure shown in FIG.
[0025]
The light emission intensity of the light-emitting diode 10 manufactured in this manner was measured and found to be 10 mcd, and this light emission luminance was twice that of the conventional pn junction GaN light-emitting diode. Further, the emission lifetime is 10 ⁴ hours was 1.5 times that of the emission lifetime of the GaN light emitting diodes of a conventional pn junction.
[0026]
Incidentally, the magnesium Mg doping gas used in the above embodiment may be methylbiscyclopentadienylmagnesium Mg (C ₆ H ₇ ) ₂ in addition to the gas described above.
[0027]
The low carrier concentration n layer 4 preferably has an electron concentration of 1 × 10 ¹⁴ to 1 × 10 ¹⁶ / cm ³ and a film thickness of 0.5 to 2 μm. When the electron concentration is 1 × 10 ¹⁶ / cm ³ or more, the emission intensity is lowered, which is not desirable. When the electron concentration is 1 × 10 ¹⁴ / cm ³ or less, the series resistance of the light emitting element becomes too high, and it is not desirable because current is generated to generate heat. . Further, if the film thickness is 2 μm or more, the series resistance of the light emitting element becomes too high, and it is not desirable because heat is generated when a current is passed. If the film thickness is 0.5 μm or less, the light emission intensity is decreased, which is not desirable.
[0028]
Further, the electron concentration of the high carrier concentration n ⁺ layer 3 is preferably 1 × 10 ¹⁶ to 1 × 10 ¹⁹ / cm ³ and the film thickness is preferably 2 to 10 μm. When the electron concentration is 1 × 10 ¹⁹ / cm ³ or more, the crystallinity deteriorates, which is not desirable. When the electron concentration is 1 × 10 ¹⁶ / cm ³ or less, the series resistance of the light-emitting element becomes too high, and it is not desirable because it generates heat when a current is applied. . Further, when the film thickness is 10 μm or more, the substrate is curved, which is not desirable, and when the film thickness is 2 μm or less, the series resistance of the light emitting element becomes too high, and heat is generated when a current is passed.
[0029]
The hole concentration of the low carrier concentration p layer 51 is preferably 1 × 10 ¹⁴ to 1 × 10 ¹⁶ / cm ³ and the film thickness is preferably 0.2 to 1 μm. When the hole concentration is 1 × 10 ¹⁶ / cm ³ or more, the matching with the low carrier concentration n-layer 4 is deteriorated and the light emission efficiency is lowered, which is not desirable. When the hole concentration is 1 × 10 ¹⁴ / cm ³ or less, the series resistance is high. It is not desirable because it becomes too much. Further, when the film thickness is 1 μm or more, it is not desirable because the series resistance is increased, and when the film thickness is 0.2 μm or less, the light emission luminance is decreased, which is not desirable.
[0030]
Further, the hole concentration of the high carrier concentration p ⁺ layer 52 is preferably 1 × 10 ¹⁶ to 2 × 10 ¹⁹ / cm ³ and the film thickness is preferably 0.2 to 0.5 μm. A p ⁺ layer with a hole concentration of 2 × 10 ¹⁹ / cm ³ or more cannot be formed. If it is 1 × 10 ¹⁶ / cm ³ or less, the series resistance is increased, which is not desirable. Further, when the film thickness is 0.5 μm or more, it is not desirable because the series resistance becomes high, and when the film thickness is 0.1 μm or less, it is not desirable because the hole injection efficiency decreases.
[0031]
Second embodiment In Fig. 8, a light emitting diode 10 has a sapphire substrate 1, on which a 500Å AlN buffer layer 2 is formed. Of On the buffer layer 2, in turn, a film thickness of about 2.2 [mu] m, the electron concentration of 2 × 10 ¹⁸ / cm high carrier concentration comprising a silicon-doped GaN of ³ n ⁺ layer 3, a thickness of about 1.5 [mu] m, the electron concentration of 1 × A low carrier concentration n layer 4 made of non-doped GaN of 10 ¹⁵ / cm ³ is formed. Further, on the low carrier concentration n-layer 4, a low carrier concentration p layer 51 made of Mg-doped GaN having a film thickness of about 0.2 μm and a hole concentration of 1 × 10 ¹⁵ / cm ³ , a film thickness of about 0.5 μm, and a hole. first high carrier concentration p ⁺ layer 52 at a concentration 1 × 10 ¹⁶ / cm ^3, a thickness of about 0.2 [mu] m, the second high carrier concentration p ⁺ layer 53 of the hole concentration 1 × 10 ¹⁷ / cm ³ is formed. An electrode 7 made of nickel connected to the second high carrier concentration p ⁺ layer 53 and an electrode 8 made of nickel connected to the high carrier concentration n ⁺ layer 3 are formed. The electrode 8 and the electrode 7 are electrically insulated and separated by the groove 9. As described above, the light-emitting diode 10 of this example is characterized in that the p-layer is formed of three layers in which the hole concentration changes in three steps. The manufacturing method is the same as in the first embodiment.
[0032]
As described above, the n layer is formed of a multi-layer in which the electron concentration increases stepwise in the direction away from the pn junction surface, and the p-layer is formed in a multi-layer in which the hole concentration increases in steps in the direction away from the pn junction surface. By applying a voltage between the p-type layer having the highest concentration and the n-type layer having the highest electron concentration, electrons and holes are efficiently accelerated in each layer, and the opposite conductivity type passes through the pn junction surface. Efficiently injected into the layer. As a result, the emission luminance was improved.
[0033]
Third embodiment In Fig. 9, a light emitting diode 10 has a sapphire substrate 1, and a 500Å AlN buffer layer 2 is formed on the sapphire substrate 1. Of On the buffer layer 2, in turn, a film thickness of about 2.2 [mu] m, the electron concentration of 2 × 10 ¹⁸ / cm high carrier concentration comprising a silicon-doped GaN of ³ n ⁺ layer 3, a thickness of about 1.5 [mu] m, the electron concentration of 1 × A low carrier concentration n layer 4 made of non-doped GaN of 10 ¹⁶ / cm ³ is formed. Furthermore, on the low carrier concentration n layer 4, a low impurity concentration i layer 61 made of Mg-doped GaN having a thickness of about 0.5 μm and an Mg concentration of 5 × 10 ¹⁹ / cm ³ , a thickness of about 0.2 μm, and Mg A high impurity concentration i ⁺ layer 62 having a concentration of 2 × 10 ²⁰ / cm ³ is formed.
[0034]
In the predetermined regions of the low impurity concentration i layer 61 and the high impurity concentration i ⁺ layer 62, a low carrier concentration p layer 501 having a hole concentration of 1 × 10 ¹⁶ / cm ³ , which has been converted to p conductivity type by electron beam irradiation, is obtained. A high carrier concentration p ⁺ layer 502 having a hole concentration of 2 × 10 ¹⁷ / cm ³ is formed.
[0035]
Further, from the upper surface of the high impurity concentration i ⁺ layer 62, hole 15 reaching the high impurity concentration i ⁺ layer 62, low impurity concentration i layer 61, through the low carrier concentration n layer 4 high carrier concentration n ⁺ layer 3 Is formed. An electrode 81 made of nickel joined to the high carrier concentration n ⁺ layer 3 through the hole 15 is formed on the high impurity concentration i ⁺ layer 62. Further, on the upper surface of the high carrier concentration p ⁺ layer 502, the electrode 71 formed of nickel for high carrier concentration p ⁺ layer 502 is formed. The electrode 81 for the high carrier concentration n ⁺ layer 3 is insulated and separated from the high carrier concentration p ⁺ layer 502 and the low carrier concentration p layer 501 by the high impurity concentration i ⁺ layer 62 and the low impurity concentration i layer 61.
[0036]
Next, a method for manufacturing the light emitting diode 10 having this structure will be described.
FIGS. 10 to 16 showing the manufacturing process are cross-sectional views relating to only one element in the wafer. Actually, the following manufacturing process is performed on the wafer on which the elements shown in the figure are repeatedly formed. Finally, the wafer is cut to form each light emitting element.
[0037]
The wafer shown in FIG. 10 is manufactured in the same manner as in the first embodiment. Next, as shown in FIG. 11, the SiO ₂ layer 11 was formed to a thickness of 2000 mm on the high impurity concentration i ⁺ layer 62 by sputtering. Next, a photoresist 12 was applied on the SiO ₂ layer 11. Then, the photoresist at the electrode formation site A corresponding to the hole 15 formed so as to reach the high carrier concentration n ⁺ layer 3 in the high impurity concentration i ⁺ layer 62 was removed by photolithography.
[0038]
Next, as shown in FIG. 12, the SiO ₂ layer 11 not covered with the photoresist 12 was removed with a hydrofluoric acid etching solution. Next, as shown in FIG. 13, the high impurity concentration i ⁺ layer 62, the low impurity concentration i layer 61 and the low carrier concentration n layer 4, which are not covered by the photoresist 12 and the SiO ₂ layer 11, A part of the upper surface of the high carrier concentration n ⁺ layer 3 was dry-etched by supplying a vacuum degree of 0.04 Torr, high-frequency power of 0.44 W / cm ² and BCl ₃ gas at a rate of 10 ml / min, and then dry-etched with Ar. In this step, a hole 15 for extracting an electrode for the high carrier concentration n ⁺ layer 3 was formed. Next, as shown in FIG. 14, the SiO ₂ layer 11 remaining on the high impurity concentration i ⁺ layer 62 was removed with hydrofluoric acid.
[0039]
Next, as shown in FIG. 15, only a predetermined region of the high impurity concentration i ⁺ layer 62 and the low impurity concentration i layer 61 is irradiated with an electron beam using a reflection electron beam diffraction apparatus, and each of the p conductivity type is irradiated. A high carrier concentration p ⁺ layer 502 having a hole concentration of 2 × 10 ¹⁷ / cm ³ and a low carrier concentration p layer 501 having a hole concentration of 1 × 10 ¹⁶ / cm ³ are formed.
[0040]
The electron beam irradiation conditions are an acceleration voltage of 10 KV, a sample current of 1 μA, a beam moving speed of 0.2 mm / sec, a beam diameter of 60 μmφ, and a degree of vacuum of 2.1 × 10 ⁻⁵ Torr. At this time, the portions other than the high carrier concentration p ⁺ layer 502 and the low carrier concentration p layer 501, that is, the portions not irradiated with the electron beam are the high impurity concentration i ⁺ layer 62 and the low impurity concentration i layer 61 of the insulator. Remains. Therefore, the high carrier concentration p ⁺ layer 502 and the low carrier concentration p layer 501 are electrically connected to the low carrier concentration n layer 4 in the vertical direction, but in the horizontal direction, the high impurity concentration i is higher than the surroundings. ^{The +} layer 62 and the low impurity concentration i layer 61 are electrically insulated and separated.
[0041]
Next, as shown in FIG. 16, a high carrier concentration p ⁺ layer 502, a high impurity concentration i ⁺ layer 62, the high impurity concentration i ⁺ layer 62 of the upper surface and the hole 15 high carrier concentration n ⁺ layer 3 through the In addition, the Ni layer 20 was formed by vapor deposition. Then, a photoresist 21 is applied on the Ni layer 20, and a predetermined amount of the photoresist 21 is left by photolithography so that electrode portions for the high carrier concentration n ⁺ layer 3 and the high carrier concentration p ⁺ layer 502 remain. Patterned into shape. Next, using the photoresist 21 as a mask, the exposed portion of the lower Ni layer 20 was etched with a nitric acid-based etchant, and the photoresist 21 was removed with acetone. In this way, as shown in FIG. 9, the electrode 81 of the high carrier concentration n ⁺ layer 3 and the electrode 71 of the high carrier concentration p ⁺ layer 502 were formed. Thereafter, the wafer formed as described above was cut for each element.
[0042]
In this manner was measured emission intensity of the light emitting diode 10 to be manufactured, like the first embodiment, a 10Mcd, emission lifetime was 10 ⁴ hours.
[0043]
Fourth embodiment The light-emitting diode 10 may be configured as shown in FIG. That is, on the buffer layer 2, a second high carrier concentration p ⁺ layer 53 having a film thickness of about 0.2 μm and a hole concentration of 2 × 10 ¹⁷ / cm ³ , a film thickness of about 0.5 μm and a hole concentration of 1 × 10 ¹⁶ / first high carrier concentration p ⁺ layer 52 cm ^3, a thickness of about 0.2 [mu] m, the low carrier concentration p layer 51 made of Mg-doped GaN of hole concentration 1 × 10 ¹⁵ / cm ³ is formed. Then, on the low carrier concentration p layer 51, in order, a low carrier concentration n layer 4 made of non-doped GaN having a film thickness of about 1.5 μm and an electron concentration of 1 × 10 ¹⁵ / cm ³ , a film thickness of about 2.2 μm and an electron concentration of 2 × A high carrier concentration n ⁺ layer 3 made of silicon-doped GaN of 10 ¹⁸ / cm ³ is formed.
[0044]
An electrode 72 made of nickel connected to the second high carrier concentration p ⁺ layer 53 and an electrode 82 made of nickel connected to the high carrier concentration n ⁺ layer 3 are formed. The electrode 82 and the electrode 72 are electrically insulated by a groove 91 formed in the high carrier concentration n ⁺ layer 3, the low carrier concentration n layer 4, the low carrier concentration p layer 51, and the first high carrier concentration p ⁺ layer 52. It is separated.
[0045]
As described above, unlike the second embodiment, this embodiment is obtained by reversing the deposition order of the p layer and the n layer on the substrate 1. Manufacture can be performed in the same manner as in the second embodiment.
[0046]
Fifth embodiment In the light emitting diode 10 of the first embodiment having the structure shown in FIG. 1, a high carrier concentration n ⁺ layer 3, a low carrier concentration n layer 4, a low carrier concentration p layer 51, and a high carrier concentration p. Each of the ⁺ layers 52 was Al _0.2 Ga _0.5 In _0.3 N. The high carrier concentration n ⁺ layer 3 was formed to have an electron concentration of 2 × 10 ¹⁸ / cm ³ by adding silicon, and the low carrier concentration n layer 4 was formed to have an electron concentration of 1 × 10 ¹⁶ / cm ³ without addition of impurities. . Low carrier concentration p layer 51 is doped with magnesium (Mg) and irradiated with an electron beam to form a hole concentration of 1 × 10 ¹⁶ / cm ^3. High carrier concentration p ⁺ layer 52 is also doped with magnesium (Mg). Then, an electron beam was irradiated to form a hole concentration of 2 × 10 ¹⁷ / cm ³ . Then, an electrode 7 made of nickel connected to the high carrier concentration p ⁺ layer 52 and an electrode 8 made of nickel connected to the high carrier concentration n ⁺ layer 3 were formed.
[0047]
Next, the light emitting diode 10 having this structure can also be manufactured in the same manner as the light emitting diode of the first embodiment. Trimethylindium (In (CH ₃ ) ₃ ) was used in addition to TMG, TMA, silane, CP ₂ Mg gas. The generation temperature and gas flow rate are the same as in the first embodiment. The flow rates of the other gases are the same as in the first embodiment except that trimethylindium is supplied at 1.7 × 10 ⁻⁴ mol / min.
[0048]
Next, in the same manner as in the first embodiment, the high carrier concentration p ⁺ layer 52 and the low carrier concentration p layer 51 are uniformly irradiated with an electron beam using a reflection electron beam diffractometer to form a p-conduction type. A semiconductor could be obtained.
[0049]
Next, as in the first example, electrodes 7 and 8 made of nickel for the high carrier concentration n ⁺ layer 3 and the high carrier concentration p ⁺ layer 52 were formed.
[0050]
The light emission intensity of the light-emitting diode 10 manufactured in this manner was measured and found to be 10 mcd, and this light emission luminance was twice that of the conventional pn junction GaN light-emitting diode. Further, the emission lifetime is 10 ⁴ hours was 1.5 times that of the emission lifetime of the GaN light emitting diodes of a conventional pn junction.
[Brief description of the drawings]
FIG. 1 is a configuration diagram illustrating a configuration of a light emitting diode according to a first specific example of the present invention.
FIG. 2 is a cross-sectional view showing a manufacturing process of the light-emitting diode of the same example.
FIG. 3 is a cross-sectional view showing a manufacturing process of the light-emitting diode of the example.
FIG. 4 is a cross-sectional view showing a manufacturing process of the light-emitting diode of the same example.
FIG. 5 is a cross-sectional view showing a manufacturing process of the light-emitting diode of the example.
6 is a cross-sectional view showing a manufacturing process of the light-emitting diode of the example. FIG.
7 is a cross-sectional view showing a manufacturing process of the light-emitting diode of the example. FIG.
FIG. 8 is a configuration diagram showing a configuration of a light emitting diode according to a second specific example of the present invention.
FIG. 9 is a configuration diagram showing a configuration of a light emitting diode according to a specific third embodiment of the present invention.
10 is a cross-sectional view showing a manufacturing step of the light-emitting diode of the same Example. FIG.
FIG. 11 is a cross-sectional view showing a manufacturing process of the light-emitting diode of the example.
FIG. 12 is a cross-sectional view showing a manufacturing process of the light-emitting diode of the example.
13 is a cross-sectional view showing a manufacturing process of the light-emitting diode of the example. FIG.
FIG. 14 is a cross-sectional view showing a manufacturing process of the light-emitting diode of the example.
15 is a cross-sectional view showing a manufacturing step of the light-emitting diode of the example. FIG.
16 is a cross-sectional view showing a manufacturing step of the light-emitting diode of the example. FIG.
FIG. 17 is a configuration diagram showing a configuration of a light emitting diode according to a specific fourth embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Light emitting diode 1 ... Sapphire substrate 2 ... Buffer layer 3 ... High carrier concentration n ⁺ layer 4 ... Low carrier concentration n layer 51,501 ... Low carrier concentration p layer 52 ... High carrier concentration p ⁺ layer (1st high carrier concentration) p ⁺ layer)
502 ... high carrier concentration p ⁺ layer 53 ... second high carrier concentration p ⁺ layer 61 ... low impurity concentration i layer 62 ... high impurity concentration i ⁺ layers 7, 8, 71, 72, 81, 82 ... electrodes 9, 91 ... groove

Claims (12)

In a light-emitting element composed of a nitrogen-3 group element compound semiconductor,
A high carrier concentration n ⁺ layer made of an n-type nitrogen-3 group element compound semiconductor doped with silicon (Si);
Low-carrier-concentration n-layer having an impurity concentration of n-type nitrogen-3 group element compound semiconductor added with no impurities and formed on the p-type layer side of the high-carrier-concentration n ⁺ layer and having an electron concentration of 1 × 10 ¹⁴ / cm ³ or more When,
A high carrier concentration p ⁺ layer made of the added p-type nitrogen -3-group element compound semiconductor of magnesium (Mg), the first high carrier concentration p hole concentration is 1 × 10 ¹⁶ / cm ³ or more ⁺ possess a layer, and a first high carrier concentration p ⁺ layer made of a high hole concentration than the high carrier concentration p ⁺ layer second high carrier concentration p ⁺ layer,
A p-type nitrogen-3 group element compound semiconductor doped with magnesium (Mg) is interposed between the low carrier concentration n layer and the first high carrier concentration p ⁺ layer, and the first high carrier concentration p. ^A low carrier concentration p-layer having a lower hole concentration than the ⁺ layer,
^3. A nitrogen-3 group compound semiconductor light emitting device, wherein the hole concentration of the low carrier concentration p layer is 1 × 10 ¹⁴ to 1 × 10 ¹⁶ / cm ³ . The nitrogen-3 group element compound semiconductor light emitting device according to claim 1 , wherein an electrode made of nickel (Ni) is formed on the second high carrier concentration p ⁺ layer. In a light-emitting element composed of a nitrogen-3 group element compound semiconductor,
An n-type nitrogen-3 group element compound semiconductor, which is formed of a multi-layer in which the electron concentration increases stepwise in the direction away from the p-type layer, of which the highest carrier concentration is formed as a high carrier concentration n ⁺ layer, The one formed with the lowest carrier concentration is the low carrier concentration n layer,
A low carrier concentration p-layer having a hole concentration of 1 × 10 ¹⁴ / cm ³ or more, composed of a p-type nitrogen-3 group element compound semiconductor doped with magnesium (Mg);
A high carrier having a hole concentration of 1 × 10 ¹⁶ / cm ³ or more made of a p-type nitrogen-3 group element compound semiconductor doped with magnesium (Mg) formed on the opposite side of the p-type layer to the n-type layer side and the density p ⁺ layer, and an electrode composed of the p ⁺ layer which is formed on nickel (Ni) possess,
^3. A nitrogen-3 group compound semiconductor light emitting device, wherein the hole concentration of the low carrier concentration p layer is 1 × 10 ¹⁴ to 1 × 10 ¹⁶ / cm ³ . The high carrier concentration p ⁺ layer, two layers of the first and high carrier concentration p ⁺ layer of low hole concentration, and a high hole concentration than the first high carrier concentration p ⁺ layer second high carrier concentration p ⁺ layer The nitrogen-3 group element compound semiconductor light emitting device according to claim 3 , wherein the electrode made of nickel (Ni) is formed in a second high carrier concentration p ⁺ layer. 5. The nitrogen-3 group element according to claim 1, wherein a hole concentration of the high carrier concentration p ⁺ layer is 1 × 10 ¹⁶ to 2 × 10 ¹⁹ / cm ^3. Compound semiconductor light emitting device. 6. The nitrogen-3 group element according to claim 1, wherein an electron concentration of the high carrier concentration n ⁺ layer is 1 × 10 ¹⁶ to 1 × 10 ¹⁹ / cm ^3. Compound semiconductor light emitting device. The nitrogen-3 group element compound according to any one of claims 1 to 6 , wherein an electron concentration of the low carrier concentration n layer is 1 x 10 ¹⁴ to 1 x 10 ¹⁶ / cm ³ . Semiconductor light emitting device. The nitrogen-3 group element compound semiconductor light emitting device according to any one of claims 1 to 7 , wherein a thickness of the low carrier concentration p layer is 0.2 to 1 µm. The nitrogen-3 group element compound semiconductor light emitting device according to any one of claims 1 to 8 , wherein the high carrier concentration p ⁺ layer has a thickness of 0.1 to 0.5 µm. The nitrogen-3 group element compound semiconductor light emitting device according to any one of claims 1 to 9 , wherein the high carrier concentration n ⁺ layer has a thickness of 2 to 10 µm. 11. The nitrogen-3 group element compound semiconductor light emitting device according to claim 1, wherein a thickness of the low carrier concentration n layer is 0.5 to 2 μm. The nitrogen-3 group element compound semiconductor light emitting device according to any one of claims 1 to 11 , wherein the high carrier concentration n ⁺ layer is made of gallium nitride (GaN).

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