Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
  • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
  • H10H20/80—Constructional details
  • H10H20/81—Bodies
  • H10H20/819—Bodies characterised by their shape, e.g. curved or truncated substrates
  • H10H20/82—Roughened surfaces, e.g. at the interface between epitaxial layers
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
  • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
  • H10H20/80—Constructional details
  • H10H20/81—Bodies
  • H10H20/819—Bodies characterised by their shape, e.g. curved or truncated substrates
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
  • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
  • H10H20/80—Constructional details
  • H10H20/81—Bodies
  • H10H20/822—Materials of the light-emitting regions
  • H10H20/824—Materials of the light-emitting regions comprising only Group III-V materials, e.g. GaP
  • H10H20/825—Materials of the light-emitting regions comprising only Group III-V materials, e.g. GaP containing nitrogen, e.g. GaN

Definitions

• the present invention relates to a semiconductor light emitting device having a semiconductor layer.
• Patent Document 1 a semiconductor light emitting device having a structure in which a plurality of semiconductor layers containing GaN are stacked on a sapphire substrate has been proposed.
• FIG. 20 shows an example of a semiconductor light emitting device manufactured by such a manufacturing method.
• a p-GaN layer 92, an active layer 93, and an n-GaN layer 94 are stacked as a semiconductor layer on a support substrate 91 on which a p-side electrode 91a is formed. Structure.
• the active layer 93 is a layer for amplifying light emitted by recombination of electrons injected from the n-GaN layer 94 and holes injected from the p-GaN layer 92. It is a multiple quantum well (hereinafter referred to as MQW) structure.
• the semiconductor light emitting device X is configured to emit light from the upper surface of the n-GaN layer 94 and the side surface 97 of the n-GaN layer 94, the active layer 93, and the p-GaN layer 92.
• Patent Document 1 Japanese Patent Application Laid-Open No. 10-012916
• Patent Document 2 JP 2003-168820 A
• GaN forming the n-GaN layer 94, the active layer 93, and the p-GaN layer 92 has a relatively high refractive index of about 2.5.
• the critical angle with air is as small as about 23 °.
• Light having an incident angle with respect to the side surface 97 larger than the critical angle is totally reflected, and is not emitted outside the semiconductor light emitting element X. Therefore, in the semiconductor light emitting device X, the increase in luminance was hindered because the proportion of the light emitted appropriately by the active layer 93 was small.
• the present invention has been conceived under the circumstances described above, and aims to increase brightness by increasing the amount of emitted light and increasing the proportion of emitted light.
• An object of the present invention is to provide a semiconductor light emitting device capable of satisfying the requirements.
• a semiconductor light-emitting device provided by the first aspect of the present invention includes a substrate, a p-type semiconductor layer supported by the substrate, and a position separated from the p-type semiconductor layer with respect to the substrate.
• a semiconductor light emitting device comprising: an n-type semiconductor layer disposed; and an active layer disposed between the p-type semiconductor layer and the n-type semiconductor layer, wherein the n-type semiconductor layer has one side A rectangular n-side electrode having the same width as one of the widths of the n-type semiconductor layer is formed, and the n-type semiconductor layer has a thickness t satisfying the relationship of Formula 1 and the semiconductor light emitting
• a plurality of convex portions are formed on the side surface extending in the stacking direction of the element, and the wavelength of light emitted from the active layer is obtained, and one of the n-type semiconductor layer and the p-type semiconductor layer is selected.
• the convex portion has an average width W 1S W ⁇ ⁇ ⁇
• W Width on the other side different from one of the ⁇ side electrodes
• a semiconductor light-emitting device provided by the second aspect of the present invention includes a semiconductor, and a semiconductor light-emitting device including an n-type semiconductor layer, an active layer, and a p-type semiconductor layer stacked on the substrate. And a plurality of convex portions are formed on the side surface extending in the stacking direction of the semiconductor light emitting device, and the wavelength of light emitted from the active layer is obtained to determine the n-type semiconductor layer and the p When the refractive index of any one of the type semiconductor layers is n, the convex portion has an average width W force W ⁇ Zn of the bottom width.
• At least one of the n-type semiconductor layer and the p-type semiconductor layer has a GaN force. According to such a configuration, it is possible to increase the light emission amount with respect to the input power amount by configuring the n-type semiconductor layer or the p-type semiconductor layer as an n -GaN layer or a p-GaN layer.
• GaN is a material with a relatively high refractive index.
• the convex portion extends in the laminating direction, and the cross-sectional shape thereof is a triangle or a semicircle. According to such a configuration, the plurality of convex portions can be shaped to appropriately emit light from the inside.
• a semiconductor light-emitting device provided by the third aspect of the present invention includes a substrate, a p-type semiconductor layer supported by the substrate, and a position separated from the p-type semiconductor layer with respect to the substrate.
• a semiconductor light emitting device comprising: an n-type semiconductor layer disposed; and an active layer disposed between the p-type semiconductor layer and the n-type semiconductor layer, wherein the n-type semiconductor layer includes a circle
• An n-side electrode having a shape is formed, and the thickness of the n-type semiconductor layer satisfies the relationship of Equation 2. It is characterized by playing.
• the representative length of the semiconductor light emitting element referred to in the present invention refers to, for example, a diameter in a circular shape and a length of one side in a rectangular shape.
• the n-type semiconductor layer has a plurality of protrusions, and the n-type semiconductor layer has a thickness t in place of the relationship of Equation 2 above. To satisfy the relationship of Equation 3.
• the n-type semiconductor layer also has an n-GaN force.
• the semiconductor light emitting element can be configured to emit blue light or green light.
• a semiconductor light-emitting device provided by the fourth aspect of the present invention includes a substrate, a p-type semiconductor layer supported by the substrate, and a position separated from the p-type semiconductor layer with respect to the substrate.
• An n-type semiconductor layer disposed between the p-type semiconductor layer and the n-type semiconductor layer.
• the n-type semiconductor layer is formed with a rectangular n-side electrode having one width that is the same as the one width of the n-type semiconductor layer.
• the n-type semiconductor layer is characterized in that the thickness t satisfies the relationship of Equation 4. Picture Br where
• the width of the n-type semiconductor layer is different from the width of the other
• W the width of the other side different from the width of one of the n-side electrodes
• the n-type semiconductor layer has a plurality of convex portions, and the thickness of the n-type semiconductor layer is changed to the relationship of Equation 4 above. To satisfy the relationship of Equation 5.
• the n-type semiconductor layer also has n-GaN force.
• the semiconductor light emitting element can be configured to emit blue light or green light.
• FIG. 1 is an overall perspective view showing a first embodiment of a semiconductor light emitting device according to the present invention.
• FIG. 2 is a plan view of the semiconductor light emitting device shown in FIG.
• FIG. 3 is a sectional view taken along line m-m in FIG.
• FIG. 4 is an enlarged cross-sectional view of a main part taken along line IV-IV in FIG.
• FIG. 5 is an enlarged cross-sectional view of a main part showing a modification of a convex part.
• FIG. 6 is an enlarged cross-sectional view of a main part showing another modification of the convex portion.
• FIG. 7 is an overall perspective view showing a second embodiment of the semiconductor light emitting device according to the present invention.
• FIG. 8 is an overall perspective view showing a third embodiment of the semiconductor light emitting device according to the present invention.
• FIG. 9 is a sectional view taken along line IX—IX in FIG.
• FIG. 10 is a cross-sectional view showing a fourth embodiment of a semiconductor light emitting element according to the present invention.
• FIG. 11 is an enlarged perspective cross-sectional view of a main part of the semiconductor light emitting element shown in FIG.
• FIG. 12 is a cross-sectional view showing a step of laminating a semiconductor layer on a sapphire substrate in the manufacturing process of the semiconductor light emitting device shown in FIG.
• FIG. 13 is a cross-sectional view showing the etching process of the semiconductor layer in the manufacturing process of the semiconductor light emitting device shown in FIG.
• FIG. 14 is a cross-sectional view showing a step of forming a reflective layer in the manufacturing process of the semiconductor light emitting element shown in FIG.
• 15 is a cross-sectional view showing a step of peeling the sapphire substrate in the manufacturing process of the semiconductor light emitting device shown in FIG.
• FIG. 16 is a cross-sectional view showing a fifth embodiment of the semiconductor light emitting device according to the present invention.
• FIG. 17 is a cross-sectional view showing a process of forming a plurality of convex portions in the manufacturing process of the semiconductor light emitting device shown in FIG.
• FIG. 18 is an enlarged perspective cross-sectional view of a relevant part showing a sixth embodiment of the semiconductor light emitting device according to the present invention.
• FIG. 19 is a cross-sectional view showing a seventh embodiment of the semiconductor light emitting device according to the present invention.
• FIG. 20 is a cross-sectional view showing an example of a conventional semiconductor light emitting device.
• the semiconductor light emitting device A101 of the present embodiment includes a substrate 110, an n-GaN layer 120, an active layer 130, p-Ga. An N layer 140 and a ZnO electrode 150 are provided.
• the semiconductor light emitting device A101 is particularly configured as a semiconductor light emitting device suitable for emitting blue light or green light.
• the substrate 110 is made of, for example, sapphire and supports the n-GaN layer 120, the active layer 130, the p-GaN layer 140, and the ZnO electrode 150. In the present embodiment, the substrate 110 has a thickness of about 80 m. On the substrate 110, for example, a buffer layer (not shown) made of A1N, GaN, AlGaN or the like for relaxing lattice strain is formed.
• the n-GaN layer 120 is made of an n-type semiconductor in which Si is doped into GaN, and is an example of the n-type semiconductor layer referred to in the present invention.
• the n-GaN layer 120 has a thickness of about 3 to 6 ⁇ m.
• the n-GaN layer 120 has a thickness of about 6 ⁇ m and a first layer 120a whose plan view dimensions are the same as the substrate 110, and a thickness of 0.2 m.
• the second layer 120b having a size in plan view smaller than that of the substrate 110.
• An n-side electrode 121 is formed on the upper surface of the first layer 120a in the figure.
• the n-side electrode 121 is formed by stacking, for example, 100 A thick Ti and 2500 A thick A1.
• the active layer 130 is a layer having an MQW structure including InGaN, for example, and is a layer for amplifying light emitted by recombination of electrons and holes.
• InGaN a plurality of InGaN layers and a plurality of GaN layers are alternately stacked.
• the InGaN layer has a band gap smaller than that of the n-GaN layer 120 because the In composition ratio is about 17%, and constitutes a well layer of the active layer 130.
• the GaN layer forms a barrier layer of the active layer 130.
• the active layer 130 is formed by laminating 8 layers each of a 30 A-thick InGaN layer and a 100 A-thick GaN layer, and the thickness is about 0.1 ⁇ m. Note that a superlattice layer (not shown) in which InGaN and GaN are alternately stacked for each atom is formed between the n-GaN layer 120 and the active layer 130 in order to reduce lattice strain. It has been.
• the p-GaN layer 140 is made of a p-type semiconductor in which GaN is doped with Mg, and is an example of the p-type semiconductor layer referred to in the present invention.
• the p-GaN layer 140 has a thickness of about 0.2 m.
• the GaN layer is between the active layer 130 and the p-GaN layer 140. (Not shown) or an InGaN layer (not shown) having an In composition of about 0.1% is formed.
• the ZnO electrode 150 is made of ZnO, which is one of transparent conductive oxides, and transmits light from the active layer 130.
• ZnO electrode 150 has a relatively low resistivity of about 2 2 10 4 ⁇ cm by doping ZnO with Ga, and its thickness is about 0.1 to 2 / ⁇ ⁇ . ing.
• a plurality of convex portions 171 are formed on the side surface 170 of the portion where the second layer 120b of the ⁇ -GaN layer 120, the active layer 130, and the p-GaN layer 140 are stacked.
• the convex portion 171 extends in the stacking direction of the second layer 120b of the n-GaN layer 120, the active layer 130, and the p-GaN layer 140, and has a triangular cross section.
• the plurality of convex portions 171 are formed on a flat surface portion excluding a curved surface portion formed on each corner portion of the side surface 170.
• FIG. 4 is an enlarged cross-sectional view of the convex portion 171.
• the average width W of the width W of the bottom of the protrusion 171 is W ⁇ ⁇ ⁇ It is supposed to satisfy.
• the average width W is , About 1
• the well layer of the active layer 130 is composed of a GaN layer that emits light having a peak wavelength of about 365 nm or more
• the average width W is about 146 nm or more.
• the height H is 2.5 / z m
• the width W is 2.1 m
• the apex angle is 46 °.
• the semiconductor light emitting device A101 can be manufactured, for example, by the following manufacturing method.
• the substrate 110 is introduced into a deposition chamber for MOCVD, and the deposition temperature, which is the temperature in the deposition chamber, is set to 1,100 ° C.
• the deposition temperature which is the temperature in the deposition chamber, is set to 1,100 ° C.
• TMG Tilgallium
• SiH gas is simultaneously supplied to dope Si, which is an n-type dopant. This allows you to
• n-GaN layer 120 is formed.
• the film formation temperature is 700 to 800 ° C., for example, about 760 ° C., NH gas, H gas
• TEG triethylgallium
• TEG trimethylindium
• MIn MIn
• NH gas, H gas, N gas, and TMG gas are supplied in a state where the film forming temperature is set to 760 ° C.
• an active layer 130 having an MQW structure can be obtained.
• a resist film is formed on the p-GaN layer 140 by a photolithography technique.
• This resist film has a shape capable of forming a plurality of convex portions 171 shown in FIG.
• a side surface 170 having a plurality of convex portions 171 is formed.
• a ZnO electrode 150 is formed on the p-GaN layer 140.
• the n-side electrode 121 is formed on the first layer 120 a of the n-GaN layer 120.
• the side in FIG. 1 and FIG. 3 can be directly or via the second layer 120b and the p-GaN layer 140 of the n-GaN layer 120.
• the light traveling forward reaches the plurality of convex portions 171.
• the plurality of convex portions 171 has an average width W satisfying the relationship of W ⁇ described above,
• the ratio of the energy converted as light emitted as light is about 19.4%
• the plurality of convex portions 171 In the case of the semiconductor light emitting device A101 provided with a ratio of emitted energy of 23.9% I was able to. That is, in the semiconductor light emitting device A101, by providing the plurality of convex portions 171 on the side surface 170, it is possible to emit more light from the active layer 130 than in the past. Thereby, the brightness of the semiconductor light emitting device A101 can be increased.
• the refractive index n of GaN as the material is as high as about 2.5, the critical angle with the air is small in the layer 110 and layer 140. . For this reason, if the side surface 170 is a smooth surface, the proportion of the light that is totally reflected increases, and the increase in luminance is hindered.
• the refractive index of GaN is adopted as the refractive index n used for W ⁇ .
• the n-GaN layer 120 and the p-GaN layer 140 are suitable for increasing the output efficiency of 140 forces.
• the plurality of convex portions 171 have a uniform cross-sectional shape in the stacking direction, they can be easily formed by the above-described etching or the like. Further, the convex section 171 having a triangular cross section also has a pair of surface forces inclined at a predetermined angle. For this reason, the partial inclination angle of the side surface 170 can be unified as a whole. This is suitable for uniformly emitting light from the inside of the semiconductor light emitting device A101.
• FIGS 5-9 illustrate other embodiments of the present invention.
• the same or similar elements as those in the above embodiment are denoted by the same reference numerals as those in the above embodiment.
• FIG. 5 shows another example of the convex portion 171.
• the convex portion 171 shown in the figure has a shape obtained by removing the top of the convex portion 171 having the above-described triangular triangular shape, and has a trapezoidal shape having a top surface 171a.
• the convex portion 171 has a width W of 2 .: m and a height H of 2 m. Also according to the present embodiment, it is possible to improve the light emission efficiency from the second layer 120b of the n-GaN layer 120, the active layer 130, and the p-GaN layer 140.
• FIG. 6 shows another example of the convex portion 171.
• the illustrated convex portion 171 is different from the above-described example in that it has a semicircular cross section.
• the convex portion 171 has a width W of 5. and a height of 2.5 / zm.
• the ratio of the energy emitted as light of the second layer 120 b force of the n ⁇ GaN layer 120 could be 23.8%.
• the convex portion referred to in the present invention is a concept including a triangular cross section, a trapezoidal cross section, and a semicircular cross section.
• the convex portions are not limited to these shapes, and can be various shapes that satisfy the above-described average width condition.
• FIG. 7 shows a second embodiment of the semiconductor light emitting device according to the present invention.
• the semiconductor light emitting device A102 of this embodiment is different from the above-described embodiment in that a plurality of convex portions 171 are also formed on the substrate 110 and the first layer 120a of the n-GaN layer 120.
• the convex portion 171 in the present embodiment has the same cross-sectional shape as the convex portion 171 shown in FIG.
• Such a plurality of convex portions 171 can be formed by etching the substrate 110 and the n-GaN layer 120 or by dicing using a dicing blade in which a triangular groove is formed. it can.
• the semiconductor light emitting device A103 of this embodiment is different from the above-described embodiment in that a plurality of cone-shaped convex portions 172 are formed. Further, the semiconductor light emitting device A103 is different in the stacked structure from the above-described embodiment.
• the semiconductor light emitting device A103 includes a substrate 110, and an n-GaN layer 120, an active layer 130, and a p-GaN layer 140 stacked on one side of the substrate 110.
• the substrate 110 is made of SiC and has a shape having a prismatic portion on the upper side in the drawing and a tapered portion on the lower side in the drawing.
• An n-side electrode 121 is formed on the surface of the substrate 110 opposite to the surface on which the n-GaN layer 120 is formed.
• a reflective layer 160 is formed on the lower surface of the p-GaN layer 140 in the figure.
• the reflective layer 160 has a structure in which metal layers such as Al, Ti, Pt, and Au are laminated, and in this embodiment, the A1 layer is disposed on the uppermost layer of the reflective layer 160 in FIG. Yes. Since the A1 layer has a relatively high reflectance, the light emitted from the active layer 130 The function of reflecting upward in the figure is exhibited.
• the reflective layer 160 can be used as a p-side electrode.
• a plurality of convex portions 172 are formed on the side surface 170 of the semiconductor light emitting device A103. However, a plurality of convex portions 172 are not formed on the portion of the side surface 170 formed by the active layer 130.
• the convex part 172 has a cone shape, the height is about 2.5 m, and the width is about 2 .: L m.
• the plurality of convex portions 172 are formed by, for example, stacking the n-GaN layer 120, the active layer 130, and the p-GaN layer 140 on the substrate 110, and then forming the upper surface of the substrate 110, the lower surface of the p-GaN layer 140.
• it can be formed by irradiating about 3.5 WZcm 2 of ultraviolet (UV) light for about 10 minutes while immersing it in about 4 molZl KOH solution at about 62 ° C with the active layer 130 covered with a mask. .
• UV ultraviolet
• the substrate 110 in the present embodiment can be used in the stacking direction. Even if it has an inclined surface, a plurality of convex portions referred to in the present invention can be appropriately provided.
• a plurality of convex portions 172 be formed on at least the substrate 110 portion of the side surface 170. Further, it is preferable that the active layer 130 in the side surface 170 is smooth in order to increase the amount of light emitted from the active layer 130.
• the force n-side electrode 121 that can improve the emission efficiency is provided on the upper surface of the first layer 120a of the n-GaN layer 120.
• N-GaN layer 120 near the end away from n-side electrode 121 does not allow sufficient current to flow, making it difficult to recombine electrons and holes throughout active layer 130. It is difficult to emit light efficiently.
• sufficient current does not flow near the end of the n-GaN layer 120 away from the n-side electrode 121, it is difficult to emit light efficiently with respect to input power. It is. [0052]
• another embodiment for solving this problem will be described.
• FIG. 10 shows a fourth embodiment of the semiconductor light emitting device according to the present invention.
• the semiconductor light emitting device A201 of this embodiment includes a support substrate 210, a p-side electrode 221, a reflective layer 222, a mask layer 222, a ZnO electrode 224, a p-GaN layer 220, an active layer 230, an n-GaN layer 240, and n
• the side electrode 241 is provided, and is configured to emit blue light or green light, for example.
• the n-side electrode 241 has a circular shape.
• the support substrate 210 supports the p-side electrode 221, the reflective layer 222, the mask layer 223, the ZnO electrode 224, the p-GaN layer 220, the active layer 230, the n-GaN layer 240, and the n-side electrode 241. ing.
• the support substrate 210 is made of a material having a high thermal conductivity such as Cu or A1N. As a result, the support substrate 210 exhibits a function of radiating heat generated when the semiconductor light emitting element A201 is energized to the outside.
• the p-side electrode 221 is formed over the entire upper surface of the support substrate 210 in the figure.
• the p-side electrode 221 is made of, for example, Au—Sn or Au.
• the reflective layer 222 has a structure in which, for example, Al, Ti, Pt, and Au are stacked in order in the upward force in the figure.
• the reflection layer 222 can reflect light emitted from the active layer 230 upward in the figure.
• the reflective layer 222 connects the p-side electrode 221 and the ZnO electrode 224 with each other. Ag may be used instead of A1.
• Mask layer 223 is used as an etching mask when etching ZnO electrode 224, p-GaN layer 220, active layer 230, and n-GaN layer 240 in the manufacturing process of semiconductor light emitting device A201 described later. It is.
• the mask layer 223 is made of SiO.
• a plurality of through holes 223a are formed in the mask layer 223.
• the plurality of through-holes 223a are for bringing the reflective layer 222 and the ZnO electrode 224 into contact with each other so as to conduct each other.
• the plurality of through holes 223a are arranged concentrically around a point located directly below the n-side electrode 241.
• the ZnO electrode 224 is made of ZnO, which is one of transparent conductive oxides, and allows the n-GaN layer 240 and the reflective layer 222 to conduct while allowing light from the active layer 230 to pass therethrough.
• ZnO electrode 224 the resistivity has been a relatively low resistance of about 2 X 10- 4 ⁇ cm, a thickness of 1000 It is supposed to be about 20000 A!
• the p-GaN layer 220 is a layer made of GaN doped with Mg, which is a p-type dopant, and is an example of a p-type semiconductor layer referred to in the present invention. Between the p-GaN layer 220 and the active layer 230, an undoped GaN layer (not shown) or an InGaN layer (not shown) containing about 1% In is formed.
• the active layer 230 is a layer having an MQW structure containing InGaN, and is a layer for amplifying light emitted by recombination of electrons and holes.
• the active layer 230 has a structure in which a plurality of InGaN layers are stacked. These InGaN layers have the composition In Ga N (
• the layer composed of InGaN is the well layer, and the layer composed of InGaN force is the barrier layer.
• a superlattice layer (not shown) made of InGaN doped with Si and GaN is formed between the active layer 230 and the n-GaN layer 240.
• the n-GaN layer 240 is a layer made of GaN doped with Si, which is an n-type dopant, and is an example of the n-type semiconductor layer referred to in the present invention.
• An n-side electrode 241 is formed on the n-GaN layer 240.
• the n-side electrode 241 has a structure in which, for example, Al, Ti, Au or Al, Mo, Au are stacked in order from the n-GaN layer 240 side.
• FIG. 11 is an enlarged perspective sectional view of a part of the n-GaN layer 240 and the n-side electrode 241.
• the n-GaN layer 240 and the n-side electrode 241 are substantially circular.
• the resistance dR when the current flows from r ⁇ r + dr is given by Equation 6.
• p is the specific resistance of the n-GaN layer 240.
• W is the diameter of the n-side electrode 241.
• V the voltage
• ⁇ the ideal coefficient of the semiconductor light emitting device
• ⁇ the Boltzmann constant
• ⁇ the Boltzmann constant
• the ideal coefficient ⁇ of GaN is a value that varies individually depending on the force of GaN, which is generally about 2 to 3, and the crystal growth state of GaN.
• Equation 9 the voltage V at which the current I becomes lZe is Equation 10.
• Equation 12 the thickness t required to set the current to lZe is expressed as Equation 12.
• the thickness t should satisfy the relationship of Equation 13.
• the representative length of the n-type semiconductor layer in the present invention refers to the diameter when these are circular, and refers to the length of one side when they are rectangular.
• the specific resistance p is 7 8 X 10— 5 ⁇ cm
• current density J is 2.5 X 10 6 A / m 2
• ideality factor ⁇ is 2
• Boltzmann coefficient ⁇ is 1. 38 X 10— 23 J / K
• the thickness t of the n-GaN layer 240 may be 1 .: L m or more.
• the sapphire substrate 250 is placed in a growth chamber for MOCVD. While supplying H gas into the growth chamber, the temperature in the growth chamber is set to about 1050 ° C.
• a GaN buffer layer (not shown) is formed on the sapphire substrate 250 in a state where the film formation temperature, which is the temperature in the growth chamber, is about 600 ° C., and thereafter N-GaN layer 240 with Si as a dopant at a deposition temperature of about 1000 ° C, InGaN-GaN superlattice layer (not shown) with Si as a dopant, MQW active layer 230, and undoped GaN layer Alternatively, an InGaN layer (not shown) containing about 1% In is sequentially stacked. Next, a P—GaN layer 220 using Mg as a dopant is formed with the growth temperature slightly raised.
• the p—GaN layer 220 is annealed to activate Mg. Then, the ZnO electrode 224 is formed by using MBE (Molecular Beam Epitaxy) method. Thereafter, a mask layer 223 having a SiO force is formed.
• MBE Molecular Beam Epitaxy
• a resist film 251 is formed by photolithography. Thereafter, the mask layer 223 is patterned by etching using the resist film 251 as a mask. Then, the resist film 251 is removed. Mesa etching is performed from the ZnO electrode 224 to the n-GaN layer 240 by ICO (inductively coupled plasma) etching using the mask layer 223.
• ICO inductively coupled plasma
• the mask layer 223 is formed by dry etching using CF gas.
• Patter Jung is given to it. Thereby, a plurality of through holes 223a arranged concentrically for contacting the reflective layer 222 and the ZnO electrode 224 are formed in the mask layer 223. At this time, the ZnO electrode 224 functions as an etching stopper. After the plurality of through holes 223a are formed, a resist film 252 is formed. In addition, A1 or Ag is vapor-deposited, and Ti, Pt, and Au are sequentially laminated to form the metal layer 222A. Then, by removing the resist film 252 and a part of the metal layer 222A, the reflective layer 222 is formed.
• a support substrate 210 is prepared, and a p-side electrode 221 made of Au—Sn or Au is formed on the support substrate 210.
• the p-side electrode 221 and the reflective layer 222 are joined together by thermal compression.
• a KrF laser oscillating at about 248 nm is irradiated through the sapphire substrate 250 toward the n-GaN layer 240.
• the interface between the sapphire substrate 250 and the n-GaN layer 240 (the GaN buffer layer (not shown)) is rapidly heated.
• the n-GaN layer 240 near the interface and the GaN buffer layer are dissolved, and the sapphire substrate 250 can be peeled off.
• This process is generally called an LLO (Laser Lift Off) process.
• a metal layer (not shown) made of Al, Ti, Au or Al, Mo, Au is formed on the n-GaN layer 240. By patterning the metal layer, an n-side electrode 241 shown in FIG. 10 is formed. Through the above steps, a semiconductor light emitting device A201 is obtained.
• the current from the n-side electrode 241 causes the thickness of the n-GaN layer 240 to be reduced.
• This current can be sufficiently spread in the in-plane direction of the n-GaN layer 240 before passing in the vertical direction.
• the n-GaN layer 240, the active layer 230, and the p-GaN layer 220 are all covered. Current can flow. Therefore, it is possible to emit light reasonably using the entire active layer 230, and the light amount of the semiconductor light emitting element A201 can be increased.
• the current flowing through the semiconductor light emitting element A201 flows through the n-side electrode 241 and the plurality of through holes 223a.
• a plurality of through-holes 223a are arranged concentrically about the center located directly under the n-side electrode 241, so that the current flowing through the semiconductor light-emitting element A201 is easily spread in the width direction of the semiconductor light-emitting element A201. And speak. With such a configuration, it is possible to further promote the light emission of the active layer 230 as a whole.
• FIG. 16 and FIG. 17 show a fifth embodiment of a semiconductor light emitting device according to the present invention and a method for manufacturing the same.
• the same or similar elements as those of the above embodiment are denoted by the same reference numerals as those of the above embodiment.
• a plurality of convex portions 240a are formed on the upper surface of the n-GaN layer 240 in the drawing.
• the convex portion 240a has a cone shape.
• the width Wc of the bottom of the convex portion 240a is the average of the width Wc when the peak wavelength of light emitted from the active layer 230 is ⁇ and the refractive index of the n-GaN layer 240 is ⁇ .
• Wc ′ is about 184 nm or more.
• the height of the convex portion 240a is approximately.
• the thickness t of the n-GaN layer 240 satisfies the relationship of Equation 14 shown below.
• Formula 14 is obtained by adding a (+ x) term to the right side of Formula 13. This increase in X corresponds to the height of the convex portion 240a described above.
• the n-side electrode 241 is formed from the state shown in FIG. 15 as shown in FIG. In FIG. 15, the surface of the n GaN layer 240 after the sapphire substrate 250 is peeled off is not anisotropic in the Ga polar plane. It has N polar surface. In this state, as shown in FIG. 17, the n-GaN layer 240 is immersed in an about 4 mol Zl KOH solution at about 62 ° C. and irradiated with about 3.5 WZcm 2 of ultraviolet (UV) light for about 10 minutes.
• UV ultraviolet
• n-GaN layer 240 a plurality of convex portions 240a satisfying the above-described relationship between the average value Wc of the bottom surface width Wc can be formed on the surface of the n-GaN layer 240.
• the thickness t of the n-GaN layer 240 can satisfy the relationship of Equation 14.
• the amount of light emitted from the active layer 230 can be increased. Further, by forming a plurality of convex portions 240a on the surface of the n-GaN layer 240, the light of the active layer 230 is totally reflected on the surface of the n-GaN layer 240 and returns to the inside of the n-GaN layer 240. Can be suppressed. Therefore, it is suitable for increasing the light amount of the semiconductor light emitting device A202.
• FIG. 10 the cross-sectional shape is shown in FIG. 10, the n-side electrode 241 has a rectangular shape, and the width of one of them (the width in the front and back direction in FIG. 10) force 3 ⁇ 4 of the GaN layer 240 One width (the width in the front and back direction in Fig. 10) is the same.
• FIG. 18 is an enlarged perspective cross-sectional view of each of the n-side electrode 241 and the n-GaN layer 240 in the sixth embodiment.
• a method for determining the thickness (length in the vertical direction in FIG. 10) t of the n-GaN layer 240 in this embodiment will be described.
• Equation 18 the thickness t required to set the current to lZe is expressed as Equation 18.
• the thickness t should satisfy the relationship of Equation 19.
• n-GaN layers 240 are formed on the upper surface of the n-GaN layer 240 in the same manner as the configuration shown in FIG.
• a configuration in which the convex portion 240a is formed may be employed.
• the thickness t of the n-GaN layer 240 is determined by Equation 20.
• the current flowing through the n-GaN layer 240 can be spread to the peripheral portion of the n-GaN layer 240, and the amount of light emission can be increased. Further, when a plurality of convex portions 240a are formed, it is possible to expect a further increase in the amount of light emission as described above. [0104] As described above, the thickness of the n-type semiconductor layer may be set to have the relationship shown in Formula 2 to 5 using the physical properties of the semiconductor material.
• the plurality of convex portions of the first to third embodiments may be formed on the side surface. Good.
• FIG. 19 shows a seventh embodiment of the semiconductor light emitting device according to the present invention.
• Each of the n-side electrode 24 1, the n-GaN layer 240, the active layer 230, and the p-GaN layer 220 is partly shown.
• FIG. In this semiconductor light emitting device a plurality of convex portions 271 similar to those in the first embodiment are formed on the side surface 270 of the n-GaN layer 240, the active layer 230, and the p-GaN layer 220 of the semiconductor light emitting device of the sixth embodiment. Is.
• the amount of light emitted from the semiconductor light emitting element can be increased, and the ratio of the light emitted from the side surface 270 can be increased, thereby increasing the brightness of the semiconductor light emitting element. Can be achieved.
• the shape of the plurality of convex portions 271 can be various shapes that satisfy the condition of the average width shown in the first embodiment. Further, as shown in the second embodiment, the plurality of convex portions 271 may be formed in other layers. Further, as shown in the third embodiment, the laminated structure of the semiconductor light emitting elements may be different.
• the n-GaN layer 240 may have a plurality of convex portions 240a formed on the upper surface.
• the semiconductor light emitting device according to the present invention is not limited to the above-described embodiment.
• each part of the semiconductor light emitting device according to the present invention can be varied in design in various ways.
• the n-type semiconductor layer and the p-type semiconductor layer referred to in the present invention are not limited to the n-GaN layer and the p-GaN layer, but may be any semiconductor layer that can inject electrons and holes into the active layer. Further, the active layer referred to in the present invention is not limited to the MQW structure.
• the semiconductor light emitting device according to the present invention can be configured to emit light of various wavelengths such as white light in addition to blue and green light.

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• 2007
  • 2007-02-22 EP EP07714804A patent/EP2003704A1/en not_active Withdrawn
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