JP2006339384A - Light emitting element, method of manufacturing same, and illuminating apparatus using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting element having a high performance wherein its light deriving efficiency for ultraviolet rays is improved more largely than conventional ones and its good luminous intensity can be obtained with a small power. <P>SOLUTION: In a gallium-nitride-based compound semiconductor layer 1, there is interposed between first and second conductivity types semiconductor layers 1b, 1c made of a gallium-nitride-based compound semiconductor containing Al, a light emitting layer 1a made of a gallium-nitride-based compound semiconductor containing no Al or containing a smaller quantity of Al than the one of the first and second conductivity types semiconductor layers 1b, 1c. The light emitting element has a translucent conductive layer 2 formed on the one-side principal surface 1b1 of the gallium-nitride-based compound semiconductor layer 1, and has a conductive layer 3 connected electrically with a layer present on the other-side principal surface 1c1 of the gallium-nitride-based compound semiconductor layer 1. Further, a substrate whereon the gallium-nitride-based compound semiconductor layer 1 has been subjected to an epitaxial growth is so removed from the other-side principal surface 1c1 of the gallium-nitride-based compound semiconductor layer 1 as to form a reflecting layer 5 on the other-side principal surface 1c1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light-emitting element (light-emitting diode; LED) that is used in, for example, a lighting device and has energy consumption efficiency twice or more that of a fluorescent lamp, a manufacturing method thereof, and a lighting device using the light-emitting element.

  A light-emitting element using a gallium nitride compound semiconductor is widely known as a blue or ultraviolet light-emitting element (see, for example, Patent Documents 1 to 5). In such a light-emitting element, it is important to efficiently extract light generated inside the light-emitting element to the outside, that is, to improve light extraction efficiency, particularly for lighting devices that are being commercialized in recent years. Is indispensable.

  4A to 4C, examples of first to third conventional light-emitting elements devised to improve the light extraction efficiency (hereinafter referred to as first conventional example, second conventional example, A sectional view of a third conventional example is shown. In addition, the same code | symbol is attached | subjected to the same thing and the overlapping description is abbreviate | omitted.

  As shown in FIG. 4A, in the first conventional example, a gallium nitride compound semiconductor layer 11 including a light emitting layer 11a is formed on one surface of a substrate 14, and the light is emitted from the light emitting layer 11a on the other surface. The reflective layer 15 for reflecting the reflected light is formed. The surface of the gallium nitride compound semiconductor layer 11 (the surface not in contact with the substrate 14) is energized to the gallium nitride compound semiconductor layer 11 and emitted from the light emitting layer 11a. A transparent electrode 16 that transmits the transmitted light and an electrode pad 17 for energizing the transparent electrode 16 are formed on a part of the transparent electrode 16 (see, for example, Patent Documents 6 to 8). Here, the gallium nitride-based compound semiconductor layer 11 has a configuration in which the light emitting layer 11a is sandwiched between semiconductor layers 11b and 11c having different conductivity types, and the surface of the semiconductor layer 11c in contact with the substrate 14 is in contact with the substrate 14. On the opposite surface, an electrode pad 13 for allowing a current to flow between the electrode pad 17 by applying a voltage is formed.

  Further, as shown in FIG. 4B, in the second conventional example, the gallium nitride compound semiconductor layer 11 is formed on the surface of the gallium nitride compound semiconductor layer 11 including the light emitting layer 11a formed on the substrate 14. A conductive reflective layer 12 is formed that energizes and reflects light emitted from the light emitting layer 11a to the substrate 14 side (see, for example, Patent Documents 9 and 11).

  As shown in FIG. 4C, in the third conventional example, light emitted from the light emitting layer 11a is gallium nitride at the interface between the gallium nitride compound semiconductor layer 11 including the light emitting layer 11a and the substrate 14. A reflective layer 18 (for example, a Bragg reflector) that reflects on the side of the compound semiconductor layer 11 is formed, and the gallium nitride compound semiconductor layer is formed on the surface of the gallium nitride compound semiconductor layer 11 (the surface that is not in contact with the substrate 14). A transparent electrode 16 that energizes 11 and transmits light emitted from the light emitting layer 11a and an electrode pad 17 that energizes the transparent electrode 16 are formed on a part of the transparent electrode 16 (for example, (See Patent Documents 12 to 20.)

In such a conventional light emitting device, the reflective layer 15, the conductive reflective layer 12 or the reflective layer 18 provided on one side of the light emitting layer 11a functions to reflect the light emitted from the light emitting layer 11a to the other side. Therefore, since the light that is originally generated radially can be concentrated and extracted in a desired direction without diverging, the light generated inside the light emitting element can be efficiently extracted to the outside. 4A and 4C, the light extraction surface is the surface side of the gallium nitride compound semiconductor layer 11. In the conventional example shown in FIG. 4B, the gallium nitride compound semiconductor is used. This is the side of the layer 11 that is in contact with the substrate 14.
JP-A-2-42770 JP-A-2-257679 JP-A-5-183189 JP-A-6-196757 JP-A-6-268257 JP-A-8-102549 Japanese Patent Laid-Open No. 2001-7397 Japanese Patent Laid-Open No. 2001-7392 JP 2000-31540 A JP 10-144961 A Japanese Patent Laid-Open No. 11-220168 JP-A-3-108778 JP-A-3-163882 Japanese Patent Laid-Open No. 9-232631 Japanese Patent Laid-Open No. 11-126925 Japanese Unexamined Patent Publication No. 11-251642 JP-A-11-274568 JP 2000-349349 JP 2001-168387 A JP 2004-031405 A

  However, in the first conventional example, the light reflected by the reflecting layer 15 formed on the substrate 14 is absorbed by the substrate 14 when propagating through the substrate 14 because it travels to the transparent electrode 16 side which is the light extraction surface. For this reason, there is a problem in that the light extraction efficiency of the entire light emitting element is not improved much even if light is reflected by the reflective layer 15. In addition, part of the light reflected by the reflective layer 15 is multiply reflected on the front and back surfaces of the substrate 14 and confined in the substrate 14, and attenuated before being extracted from the transparent electrode 16 side that is the light extraction surface. There is a problem that the light extraction efficiency of the entire light emitting device is not improved so much.

  In the second conventional example, the light reflected by the conductive reflective layer 12 formed on the gallium nitride compound semiconductor layer 11 contacts the gallium nitride compound semiconductor layer 11 of the substrate 14 which is the light extraction surface. Since the light is absorbed by the substrate 14 when propagating through the substrate 14 because it is directed to the non-surface side, the light extraction efficiency of the entire light-emitting element is not significantly improved even if light is reflected by the conductive reflective layer 12 There was a problem. In addition, a part of the light reflected by the conductive reflective layer 12 is multiply reflected on the front and back surfaces of the substrate 14 and confined in the substrate 14 and attenuates before being extracted from the light extraction surface side. There was a problem that the light extraction efficiency was not improved so much.

  In the third conventional example, in order to grow the gallium nitride compound semiconductor layer 11 on the reflective layer 18, the material, crystallinity, manufacturing method, and the like of the reflective layer 18 are limited. As a result, it is difficult to increase the reflection efficiency of the reflection layer 18 due to the inability to use materials and manufacturing methods for realizing high reflection efficiency, and it is optimal for the wavelength of light emitted from the light emitting layer 11a. Inability to use simple materials and manufacturing methods limits the wavelength of the reflected light. Therefore, there is a problem that the light extraction efficiency of the entire light emitting element is not improved so much by the reflective layer 18.

  In each of the first, second, and third conventional examples, the semiconductor layer 11c, the light emitting layer 11a, and the semiconductor layer 11b (semiconductor layer 11) made of a gallium nitride compound semiconductor layer are epitaxially grown. Since the buffer layer interposed between the semiconductor layer 11 and the substrate 14 does not contain either aluminum or gallium or contains aluminum and gallium only in part, the semiconductor layer 11b or the semiconductor layer 11c The forbidden bandwidth becomes relatively small, and the absorption of light on the short wavelength side such as ultraviolet light increases. Therefore, the transmittance of the semiconductor layer 11 with respect to ultraviolet light is reduced, and there is a problem that the light extraction efficiency of ultraviolet light extracted from any one of the main surface sides of the semiconductor layer 11 cannot be increased so much.

Further, in the conventional method for manufacturing a light emitting element, a single crystal substrate such as sapphire, SiC, Si, GaAs or the like having a lattice constant greatly different from that of a gallium nitride compound semiconductor is used as a substrate on which the semiconductor layer 11 is epitaxially grown. Therefore, a gallium nitride compound semiconductor containing aluminum having a good crystal quality as a buffer layer or a gallium nitride compound semiconductor layer formed thereon (general formula Al _x Ga _1-x N, 0 <x <1) There was a problem that it was actually difficult to form a layer. In general, as the content of aluminum contained in a gallium nitride compound semiconductor increases, the crystal quality of the gallium nitride compound semiconductor tends to decrease.

  Therefore, the present invention has been completed in view of the above circumstances, and the purpose thereof is to improve the light extraction efficiency of ultraviolet light more greatly, and as a result, high performance capable of obtaining good light emission intensity with low power. An object of the present invention is to provide a light-emitting element, a method for manufacturing a light-emitting element capable of reliably manufacturing a high-performance light-emitting element, and an illumination device using the high-performance light-emitting element.

Light-emitting element of the present invention has the formula _{Ga 1-x-y In y} Al x N ( However, 0 <x + y <1 , x> 0, y ≧ 0 to.) Of gallium nitride-based compound represented by the semiconductor With the first conductivity type semiconductor layer and the chemical formula Ga _{1-x′-y ′} In _{y ′} Al _{x ′} N (where 0 <x ′ + y ′ <1, x ′> 0, y ′ ≧ 0). between the second conductive type semiconductor layer composed of gallium nitride-based compound semiconductor represented by the chemical formula _{Ga 1-x "-y" in} y "Al x" N ( However, 0 <x "+ y"<1, x Gallium nitride compound semiconductor layer formed by sandwiching a light emitting layer made of a gallium nitride compound semiconductor represented by “> 0, y” ≧ 0) (where x, x ′> x ″, y, y ′ ≦ y ″)), a translucent conductive layer formed on one main surface, and the gallium nitride compound semiconductor layer. And a conductive layer electrically connected to the semiconductor layer on the main surface side, and a substrate used for epitaxial growth of the gallium nitride compound semiconductor layer from the other main surface of the gallium nitride compound semiconductor layer. It is removed, and a reflection layer is formed on the other main surface side.

The light emitting device manufacturing method of the present invention includes a chemical formula Ga on a main surface of a substrate made of a diboride single crystal represented by a chemical formula XB ₂ (wherein X includes at least one of Ti and Zr). _{1-x′-y ′} In _{y ′} Al _{x ′} N (provided that 0 <x ′ + y ′ <1, x ′> 0, y ′ ≧ 0). A buffer layer, a second conductive semiconductor layer having the same composition as the buffer layer, and a chemical formula Ga _{1-x ″ -y ″} In _{y ″} Al _{x ″} N (where 0 <x ″ + y ″ <1, x ″> A light-emitting layer made of a gallium nitride compound semiconductor represented by 0, y ″ ≧ 0) and a chemical formula Ga _1-xy In _y Al _x N (where 0 <x + y <1, x> 0, and a first conductivity type semiconductor layer made of a gallium nitride compound semiconductor represented by A step of epitaxial growth (where x, x ′> x ″, y, y ′ ≦ y ″), a step of forming a translucent conductive layer on the first conductive type semiconductor layer, and the translucency A step of removing the substrate from the buffer layer while protecting the conductive conductive layer, and a step of forming a reflective layer on the surface of the buffer layer from which the substrate is removed.

  An illuminating device of the present invention includes the light-emitting element of the present invention having the above structure, and at least one of a phosphor and a phosphor that emit light upon receiving light emitted from the light-emitting element.

According to the light-emitting element of the present invention, a gallium nitride compound semiconductor represented by the chemical formula Ga _1-xy In _y Al _x N (where 0 <x + y <1, x> 0, y ≧ 0). And a chemical formula Ga _{1-x′-y ′} In _{y ′} Al _{x ′} N (where 0 <x ′ + y ′ <1, x ′> 0, y ′ ≧ 0). between the second conductive type semiconductor layer composed of gallium nitride-based compound semiconductor represented by), the chemical formula _{Ga 1-x "-y" in} y "Al x" N ( However, 0 <x "+ y"<1 , X ″> 0, y ″ ≧ 0.) A gallium nitride compound semiconductor layer formed by sandwiching a light emitting layer made of a gallium nitride compound semiconductor (where x, x ′> x “, Y, y ′ ≦ y”)), a translucent conductive layer formed on one main surface, and a gallium nitride compound semiconductor layer. A conductive layer electrically connected to the semiconductor layer on the other main surface side, and the substrate used to epitaxially grow the gallium nitride compound semiconductor layer from the other main surface of the gallium nitride compound semiconductor layer is removed. In addition, since the reflective layer is formed on the other main surface side, the reflective layer and the translucent conductive layer efficiently reflect the light emitted from the light emitting layer to the one main surface side of the gallium nitride compound semiconductor layer. In order to emit the reflected light from one main surface side of the gallium nitride compound semiconductor layer without being absorbed by the substrate, the one main surface side does not diverge the light generated inside the light emitting layer. It can be efficiently extracted by concentrating on.

  In addition, since the first and second conductivity type semiconductor layers are gallium nitride compound semiconductors containing aluminum, the forbidden band width in the first and second conductivity type semiconductor layers is relatively large, and the first and second conductivity types Absorption of light on the short wavelength side such as ultraviolet light in the semiconductor layer can be reduced. The first and second conductive semiconductor layers made of the gallium nitride-based compound semiconductor containing aluminum, and the ultraviolet light generated in the light emitting layer by the reflective layer by the action of the reflective layer and the translucent conductive layer. It is possible to efficiently extract ultraviolet light by being reflected well on the layer side and being transmitted through the first and second conductive semiconductor layers with little loss and concentrating on the second conductive semiconductor layer side. As a result, the light extraction efficiency from the one main surface side of the gallium nitride-based compound semiconductor layer is greatly improved, and a high performance capable of obtaining a good light emission intensity with a small power. In addition, since the reflective layer can be provided on the surface of the gallium nitride-based compound semiconductor layer from which the substrate has been removed without using epitaxial growth, the reflective layer material and fabrication process can be selected from an optical standpoint. The material and surface shape of the reflective layer can be made appropriate so that the reflection characteristics are improved.

According to the method for manufacturing a light emitting device of the present invention, a chemical formula is formed on the main surface of a substrate made of a diboride single crystal represented by the chemical formula XB ₂ (where X includes at least one of Ti and Zr). From a gallium nitride compound semiconductor represented by Ga _{1-x′-y ′} In _{y ′} Al _{x ′} N (where 0 <x ′ + y ′ <1, x ′> 0, y ′ ≧ 0). And a second conductivity type semiconductor layer having the same composition as the buffer layer, and a chemical formula Ga _{1-x ″ -y ″} In _{y ″} Al _{x ″} N (where 0 <x ″ + y ″ <1, x ″ > 0, y ″ ≧ 0) and a light-emitting layer made of a gallium nitride compound semiconductor represented by the chemical formula Ga _1-xy In _y Al _x N (where 0 <x + y <1, x> 0). , Y ≧ 0.) A first conductivity type semiconductor layer made of a gallium nitride compound semiconductor represented by A step of epitaxial growth in order (where x, x ′> x ″, y, y ′ ≦ y ″), a step of forming a translucent conductive layer on the first conductive type semiconductor layer, and translucency The substrate is removed from the gallium nitride-based compound semiconductor layer by including a step of removing the substrate from the buffer layer while protecting the conductive layer and a step of forming a reflective layer on the surface of the buffer layer from which the substrate is removed. In this process, the surface of the gallium nitride compound semiconductor layer and the translucent conductive layer formed thereon can be prevented from being deteriorated by, for example, contamination with an etching solution, corrosion, or stress. A high-performance light-emitting element can be reliably manufactured.

  In addition, the surface on which the reflective layer is formed can be made flat by chemically etching a substrate made of diboride single crystal, and a good reflective layer can be formed there, so that high performance A light-emitting element can be reliably manufactured.

  In addition, when a buffer layer made of a gallium nitride compound semiconductor containing aluminum and a second conductivity type semiconductor layer having the same composition as the buffer layer formed thereon are epitaxially grown on a substrate made of a diboride single crystal. In addition, since the lattice constants of the substrate, the buffer layer, and the second conductivity type semiconductor layer are well matched, the entire buffer layer and the second conductivity type semiconductor layer may be a gallium nitride compound semiconductor layer containing aluminum. Can grow them well. As a result, a method for manufacturing a light-emitting element capable of reliably manufacturing a gallium nitride-based compound semiconductor layer containing aluminum of good crystal quality is obtained.

  In addition, according to the illumination device of the present invention, since the light-emitting element of the present invention having the above-described configuration and at least one of a phosphor and a phosphor that emit light upon receiving light emitted from the light-emitting element are provided, low power consumption is achieved. In this case, the phosphor or phosphor is strongly excited by the light emitted from the light-emitting element having a good emission intensity, so that a good illuminance can be obtained with a small electric power. In addition, such an illumination device of the present invention is superior in energy saving and downsizing than conventional fluorescent lamps and discharge lamps, and is superior to fluorescent lamps and discharge lamps.

  A light emitting device and a method for manufacturing the same according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic sectional view showing an example (first light emitting element) of an embodiment of a light emitting element of the present invention. FIG. 2 is a schematic cross-sectional view showing another example (second light emitting element) of the embodiment of the light emitting element of the present invention. 3A to 3G are schematic cross-sectional views for each process showing the method for manufacturing a light-emitting element of the present invention. In these drawings, the same portions are denoted by the same reference numerals, and redundant description is omitted.

  1 to 3, 1 is a gallium nitride compound semiconductor layer, 1 a is a light emitting layer, 1 b is a first conductivity type semiconductor layer, 1 c is a second conductivity type semiconductor layer, 1 b 1 is a gallium nitride compound semiconductor layer 1. 1c1 is the other main surface of the gallium nitride compound semiconductor layer 1, 2 is a translucent conductive layer, 3 is a conductive layer, 4 is a substrate for epitaxial growth of the gallium nitride compound semiconductor layer 1, Reference numeral 5 denotes a reflection layer, 6 denotes an electrode pad, 7 denotes a first conductive layer, 8 denotes a second conductive layer, 9 denotes a base, and 10 denotes a protective film.

An example of embodiment of the light emitting device of the present invention shown in FIG. 1 has the formula _{Ga 1-x-y In y} Al x N ( where the 0 <x + y <1, x> 0, y ≧ 0.) In a first conductivity type semiconductor layer 1b composed of a gallium nitride compound semiconductor represented by the chemical formula _{Ga 1-x'-y 'In} y' Al x 'N ( However, 0 <x' + y '<1,x'> 0, y ′ ≧ 0)) between the second conductivity type semiconductor layer 1c made of a gallium nitride compound semiconductor represented by the chemical formula Ga _{1-x ″ -y ″} In _{y ″} Al _{x ″} N ( However, a gallium nitride compound in which a light emitting layer 1a made of a gallium nitride compound semiconductor represented by 0 <x ″ + y ″ <1, x ″> 0, y ″ ≧ 0 is sandwiched and bonded. Translucent formed on one main surface 1b1 of the semiconductor layer 1 (where x, x ′> x ″, y, y ′ ≦ y ″). A conductive layer 2 and a conductive layer 3 electrically connected to a layer on the other main surface 1c1 side of the gallium nitride based compound semiconductor layer 1 (in this example, the second conductive type semiconductor layer 1c), and gallium nitride The substrate 9 used for epitaxial growth of the gallium nitride compound semiconductor layer 1 is removed from the other main surface 1c1 of the system compound semiconductor layer 1, and the reflection layer 5 is formed on the other main surface 1c1.

  More specifically, in this configuration, the first conductive semiconductor layer 1b and the second conductive semiconductor layer 1c are a p-type semiconductor layer and an n-type semiconductor layer, respectively. In order to make a gallium nitride-based compound semiconductor a p-type semiconductor, for example, magnesium (Mg), which is a group 2 element in the atomic periodic table, may be mixed into the gallium nitride-based compound semiconductor as a dopant. In addition, in order to make a gallium nitride compound semiconductor an n-type semiconductor, a gallium nitride compound semiconductor, for example, silicon (Si) which is an element of Group 4 in the atomic periodic table may be mixed as a dopant.

  Moreover, both the 1st conductivity type semiconductor layer 1b and the 2nd conductivity type semiconductor layer 1c shall consist of a gallium nitride type compound semiconductor containing aluminum (Al), and both are contained rather than the aluminum contained in the light emitting layer 1a. To increase. In this case, since the forbidden band widths of the first and second conductive semiconductor layers 1b and 1c are both larger than the forbidden band width of the light emitting layer 1a, electrons and holes are confined in the light emitting layer 1a. Electrons and holes can be efficiently recombined to emit light with strong emission intensity.

  The first and second conductive semiconductor layers 1b and 1c are gallium nitride-based compound semiconductor layers containing aluminum, so that the forbidden band widths of the first and second conductive semiconductor layers 1b and 1c are relatively small. As a result, the absorption of light on the short wavelength side such as ultraviolet light in the first and second conductive semiconductor layers 1b and 1c can be reduced. The first conductive semiconductor layer 1b and the second conductive semiconductor layer 1c may be an n-type semiconductor layer and a p-type semiconductor layer, respectively.

  The composition of the gallium nitride compound semiconductor in the light emitting layer 1a may be set to an appropriate value from a desired light emission wavelength. For example, if it is made of GaN containing neither aluminum nor indium, the forbidden band width is about 3.4 electron volts (eV), and the light emitting layer 1a emits light in the ultraviolet region having an emission wavelength of about 365 nanometers (nm). It will be. When the emission wavelength is shorter than this, the light emitting layer 1a is made of a gallium nitride compound semiconductor containing aluminum, which is an element for increasing the forbidden bandwidth, in an amount set according to the emission wavelength. It should be composed. The light emitting layer 1a may contain indium (In), which is an element for reducing the forbidden band width. Therefore, the composition ratio of aluminum, indium, and gallium may be set appropriately by adding more aluminum so that the desired emission wavelength is obtained. The light emitting layer 1a is a multi-quantum quantum well structure (MQW: Multi Quantum) which is a superlattice in which a quantum well structure composed of a barrier layer having a wide forbidden band and a well layer having a narrow forbidden band is regularly stacked a plurality of times. Wells) (not shown).

The translucent conductive layer 2 is a layered material made of a material that can form a good ohmic junction with the first conductive type semiconductor layer 1b and can transmit the light generated in the light emitting layer 1a without loss. Is used. Examples of such materials include thinly formed aluminum (Al), titanium (Ti), nickel (Ni), chromium (Cr), indium (In), tin (Sn), molybdenum (Mo), and silver. (Ag), gold (Au), niobium (Nb), tantalum (Ta), vanadium (V), platinum (Pt), lead (Pb), beryllium (Be), gold-silicon (Au-Si) alloy, gold - germanium (Au-Ge) alloy, gold - zinc (Au-Zn) alloy, gold - beryllium (Au-Be) film or a tin oxide such as alloy _(SnO 2), indium oxide _{(in 2 O} 3), oxide A transparent conductive film such as indium tin (ITO) may be used. Further, a plurality of layers selected from the above materials may be laminated, or a mesh-like film provided with portions where no thin film is formed may be used. In particular, the translucent conductive layer 2 is formed by forming a thin tantalum (Ta) layer and a gold (Au) layer in order from the semitransparent electrode or the gallium nitride compound semiconductor layer 1 side in which the tantalum (Ta) layer is thinly formed. The laminated semi-transparent electrode is preferable in that a good ohmic junction with the p-type semiconductor layer can be obtained and a current can be supplied uniformly to the light emitting layer 1a.

Further, the conductive layer 3 is made of a layer made of a material capable of forming a good ohmic junction with the second conductive semiconductor layer 1c (n-type semiconductor layer). Examples of such materials include aluminum (Al), titanium (Ti), nickel (Ni), chromium (Cr), indium (In), tin (Sn), molybdenum (Mo), silver (Ag), Gold (Au), Niobium (Nb), Tantalum (Ta), Vanadium (V), Platinum (Pt), Lead (Pb), Tungsten (W), Tin oxide (SnO ₂ ), Indium oxide (In ₂ O ₃ ) , Indium tin oxide (ITO), gold-silicon (Au-Si) alloy, gold-tin (Au-Sn) alloy, gold-germanium (Au-Ge) alloy, indium-aluminum (In-Al) alloy, etc. May be used. In particular, when the conductive layer 3 is a titanium (Ti) layer or a titanium (Ti) layer and an aluminum (Al) layer stacked in this order from the second conductive type semiconductor layer 1c side, a good ohmic junction and a good quality are obtained. This is preferable in that both the bonding strength can be obtained.

  In FIG. 1, a region where the light emitting layer 1a and the first conductivity type semiconductor layer 1b are not formed is provided in the second conductivity type semiconductor layer 1c, and the conductive layer 3 is formed in this region. Thus, the conductive layer 3 is preferably formed on the surface opposite to the surface of the gallium nitride compound semiconductor layer 1 on the other main surface 1c1 side. Thereby, when the light emitting element is mounted on a mounting substrate or the like, the translucent conductive layer 2 and the conductive layer 3 are formed in the same direction, so that mounting is facilitated.

  In addition, an electrode pad 6 for connecting a conductive wire or the like for electrical connection with the outside is provided on part of the translucent conductive layer 2. The electrode pad 6 may be made of, for example, a titanium (Ti) layer or a layer in which a titanium (Ti) layer and a gold (Au) layer are laminated in this order from the translucent conductive layer 2 side. Further, the same material as the electrode pad 6 may be formed on the conductive layer 3.

The reflective layer 5 is a layer having a smooth surface made of a material that reflects the light generated by the light emitting layer 1a without loss. Examples of such materials include aluminum (Al), titanium (Ti), nickel (Ni), chromium (Cr), indium (In), tin (Sn), molybdenum (Mo), silver (Ag), Gold (Au), Niobium (Nb), Tantalum (Ta), Vanadium (V), Platinum (Pt), Lead (Pb), Beryllium (Be), Tin oxide (SnO ₂ ), Indium oxide (In ₂ O ₃ ) , Indium tin oxide (ITO), gold-silicon (Au-Si) alloy, gold-germanium (Au-Ge) alloy, gold-zinc (Au-Zn) alloy, gold-beryllium (Au-Be) alloy, etc. May be used. Among these, titanium (Ti), aluminum (Al), or silver (Ag) is preferable because it has a high reflectance with respect to ultraviolet to near-ultraviolet light generated by the light emitting layer 1a. In addition, a plurality of layers selected from the above materials may be stacked.

  Note that the surface of the reflective layer 5 does not necessarily have to be perfectly smooth, but care must be taken because the reflectance may decrease if the surface is not smooth. The reflective layer 5 is not necessarily a metal as long as it has a function of reflecting light. However, if the reflective layer 5 is generally a metal having good thermal conductivity, the heat generated in the gallium nitride-based compound semiconductor layer 1 can be reduced. It is preferable because heat can be radiated well through the reflective layer 5.

  The gallium nitride-based compound semiconductor layer 1 may have a later-described buffer layer bonded to the main surface (the other main surface 1c1) on the second conductivity type semiconductor layer 1c side. In this case, the reflective layer 5 may be formed on the surface from which the substrate 9 for epitaxially growing the gallium nitride compound semiconductor layer 1 is removed from the buffer layer.

  Next, the operation of the light emitting device of the present invention will be described below. That is, in the above configuration, by applying a forward bias voltage to the translucent conductive layer 2 and the conductive layer 3, a bias current is caused to flow through the gallium nitride compound semiconductor layer 1, and the wavelength of 350 to 400 nm is generated in the light emitting layer 1a. One of the gallium nitride-based compound semiconductor layers 1 is generated by the reflective layer 5 from the ultraviolet to near-ultraviolet light emitted from the light emitting layer 1a. Reflecting the main surface 1b1 side, transmitting the ultraviolet to near-ultraviolet light emitted from the light-emitting layer 1a by the translucent conductive layer 2 and the ultraviolet to near-ultraviolet light reflected by the reflecting layer 5 to the outside of the light-emitting element It operates to extract the ultraviolet to near ultraviolet light.

  In this way, the substrate 4 (FIG. 3 (a) is formed on the path until the light emitted from the light emitting layer 1a and the light reflected by the reflective layer 5 are emitted from the one main surface side 1b1 of the gallium nitride compound semiconductor layer 1. )), The light can be emitted without being absorbed by the substrate 4. As a result, according to the first light emitting device of the present invention, the reflective layer 5 and the translucent conductive layer 2 emit ultraviolet light to near ultraviolet light emitted from the light emitting layer 1a on one main surface of the gallium nitride-based compound semiconductor layer 1. The light is efficiently reflected on the 1b1 side, and the reflected light is emitted from the one main surface 1b1 side of the gallium nitride compound semiconductor layer 1 without being absorbed by the substrate 4, so that the light is generated inside the light emitting layer 1a. The light can be efficiently extracted by being concentrated on the one main surface 1b1 side of the gallium nitride compound semiconductor layer 1 without diverging light. Therefore, the light extraction efficiency from the one main surface 1b1 side of the gallium nitride-based compound semiconductor layer 1 is greatly improved, and a high performance capable of obtaining a good emission intensity with a small power.

  Furthermore, since the reflective layer 5 can be provided on the surface of the gallium nitride compound semiconductor layer 1 from which the substrate 4 has been removed without using epitaxial growth, various materials and fabrication processes for the reflective layer 5 are selected from an optical standpoint. Therefore, the material, surface shape, and the like of the reflective layer 5 can be made appropriate so that the reflection characteristics are improved. By using such a reflective layer 5, according to the first light emitting device of the present invention, the light generated inside the light emitting layer 1 a is efficiently reflected on the other main surface 1 c 1 side of the gallium nitride compound semiconductor layer 1. Therefore, the light extraction efficiency from the one main surface 1b1 side of the gallium nitride-based compound semiconductor layer 1 is greatly improved, and a high performance capable of obtaining a good emission intensity with a small electric power is obtained.

  Further, as shown in FIG. 1, a substrate 9 may be bonded on the reflective layer 5. The substrate 9 is reflected on the surface of the gallium nitride compound semiconductor 1 from which the substrate 4 has been removed after removing the substrate 4 used to form the gallium nitride compound semiconductor layer 1 from the other main surface 1c1 side. Joined through layer 5. According to such a first light emitting element, since the gallium nitride compound semiconductor layer 1 can be mechanically reinforced by the base 9, it becomes easy to handle with high strength, and as a result, has high reliability. And high productivity. For example, the base 9 functions as a base of the gallium nitride compound semiconductor layer 1 when the gallium nitride compound semiconductor layer 1 is mounted on a mounting substrate or the like, and the light emitting element is securely fixed to the mounting substrate or the like mechanically. Can be made.

  Since such a substrate 9 does not require the epitaxial growth of the gallium nitride compound semiconductor layer 1 unlike the substrate 4, the material can be freely selected. For this reason, for example, a material can be selected as the base 9 such that the heat dissipation characteristic is heat dissipation, the electric conduction characteristic is conductivity, and the mechanical characteristic is the optimum strength against stress. Si) is preferred. Silicon (Si) is excellent in terms of workability, which is one of mechanical characteristics. For this reason, by using the substrate 9 made of such a material, after the light emitting element is manufactured at the wafer level, the substrate 9 is divided by dicing or the like at the separation position of each light emitting element, so that each light emitting element can be easily manufactured. Therefore, it can be made excellent in mass productivity. Silicon (Si) can be made conductive or semi-insulating by mixing a dopant. For this reason, for example, when it is desired to supply a DC voltage to the second conductivity type semiconductor layer 1c through the substrate 9, the substrate 9 may be conductive, and when an AC voltage is to be applied, it is semi-insulating. And it is sufficient. Thus, the light-emitting element using the semi-insulating base 9 has a low dielectric loss due to the skin effect, and therefore has a low loss of the applied AC voltage and is efficient.

In addition to silicon (Si), the base material 9 is made of aluminum nitride (AlN), silicon carbide (SiC), copper (Cu), copper-tungsten (Cu-W) alloy, alumina (Al ₂ O ₃ ). However, it is preferable to select an appropriate one according to the use because it has advantages and disadvantages in other characteristics.

  By using such a base 9, the base 9 mechanically reinforces the gallium nitride compound semiconductor layer 1 so that the base 9 can be easily handled with high strength, and the base 9 has excellent heat dissipation. Can release the heat generated in the gallium nitride-based compound semiconductor layer 1 to the mounting substrate or the like through the reflective layer 5 and the base 9, thereby increasing the reliability of the light emitting element. If a higher one is used, electrical connection can be made to the gallium nitride compound semiconductor layer 1 from the mounting substrate side, and mounting can be facilitated. If a semi-insulating one is used, a mounting substrate can be obtained. Insulating properties can be ensured.

Next, another example (second light emitting element) of the embodiment of the light emitting element of the present invention will be described below. The second light-emitting element is made of a gallium nitride compound semiconductor represented by the chemical formula Ga _1-xy In _y Al _x N (where 0 <x + y <1, x> 0, y ≧ 0). a first conductivity type semiconductor layer 1b, formula _{Ga 1-x'-y 'In} y' Al x 'N ( However, 0 <x' and + y '<1, x'> 0, y '≧ 0.) The chemical formula Ga _{1-x ″ -y ″} In _{y ″} Al _{x ″} N (where 0 <x ″ + y ″ <1) , X ″> 0, y ″ ≧ 0.) A gallium nitride compound semiconductor layer 1 in which a light emitting layer 1a made of a gallium nitride compound semiconductor is sandwiched and joined (where x, x ′) > X ″, y, y ′ ≦ y ″) and the light-transmitting conductive layer 7 formed on the one main surface 1b1 and the gallium nitride system. A conductive reflective layer 8 which is a conductive layer electrically connected to a layer on the other main surface 1c1 side of the compound semiconductor layer 1 (second conductive type semiconductor layer 1c in the example of FIG. 2); The substrate 4 used for epitaxial growth of the gallium nitride compound semiconductor layer 1 is removed from the other main surface 1c1 of the system compound semiconductor layer 1, and the conductive reflection layer 8 which is a conductive reflection layer is formed on the other main surface 1c1. Is formed.

  In the above structure, the light-transmitting conductive layer 7 has the same structure as the light-transmitting conductive layer 2 in the light-emitting element shown in FIG. 1, and the same material can be used.

  In addition, the conductive reflective layer 8 which is a reflective layer functions to have the functions of the conductive layer 3 and the reflective layer 5 in the light-emitting element shown in FIG. 1, and is a good ohmic layer for the second conductive semiconductor layer 1c. A smooth layer is formed of a material that can be bonded and can reflect the light generated in the light emitting layer 1a without loss.

Examples of such materials include aluminum (Al), titanium (Ti), nickel (Ni), chromium (Cr), indium (In), tin (Sn), molybdenum (Mo), silver (Ag), Gold (Au), Niobium (Nb), Tantalum (Ta), Vanadium (V), Platinum (Pt), Lead (Pb), Beryllium (Be), Tin oxide (SnO ₂ ), Indium oxide (In ₂ O ₃ ) , Indium tin oxide (ITO), gold-silicon (Au-Si) alloy, gold-germanium (Au-Ge) alloy, gold-zinc (Au-Zn) alloy, gold-beryllium (Au-Be) alloy, etc. May be used. Among these, aluminum (Al) or silver (Ag) is preferable because it has a high reflectance with respect to blue or ultraviolet light emitted from the light emitting layer 1a. Further, a plurality of layers selected from the above materials may be laminated. Note that the surface of the conductive reflective layer 8 does not necessarily have to be perfectly smooth, but care must be taken because the reflectance may decrease if the surface is not smooth.

  According to another example of the embodiment of the light emitting device of the present invention shown in FIG. 2, since it has the above-described configuration, the transmissive structure sandwiching the gallium nitride-based compound semiconductor layer 1 as in the light emitting device shown in FIG. The photoconductive layer 7 and the electroconductive reflective layer 8 reflect the light emitted from the light emitting layer 1a to the electroconductive reflective layer 8 side and transmit the reflected light to the translucent conductive layer. The light is emitted from the side 7 without being absorbed by the substrate 9. Therefore, the light generated inside the light emitting layer 1a can be concentrated and taken out in a desired direction (in this example, the translucent conductive layer 7 side) without diverging, so that the gallium nitride compound semiconductor layer 1 The light extraction efficiency from the light-transmitting conductive layer 7 side is greatly improved, and a high performance capable of obtaining a good emission intensity with a small electric power.

  Moreover, since both the translucent conductive layer 7 and the conductive reflective layer 8 can be provided on the gallium nitride compound semiconductor layer 1 without using epitaxial growth, the translucent conductive layer 7 and the conductive reflective layer 8 are provided. Various materials and manufacturing processes can be selected from an optical standpoint. As a result, the materials of the translucent conductive layer 7 and the conductive reflective layer 8 are improved so that the reflection characteristics of light reflected by the conductive reflective layer 8 and the transmission characteristics of light transmitted through the translucent conductive layer 7 are improved. The surface shape and the like can be made appropriate.

  In addition, according to another example of the embodiment of the light emitting device of the present invention shown in FIG. 2, the following other effects are obtained.

  The translucent conductive layer 7 and the conductive reflective layer 8 are arranged so as to sandwich both main surfaces 1b1 and 1c1 of the gallium nitride compound semiconductor layer 1 so as to apply a bias voltage to the gallium nitride compound semiconductor layer 1. Therefore, a uniform bias current can be supplied to the gallium nitride compound semiconductor layer 1 by the translucent conductive layer 7 and the conductive reflective layer 8. As a result, since the entire light emitting layer 1a can be made to emit light satisfactorily, a high performance capable of obtaining a better light emission intensity with a small electric power is obtained.

  In addition, it is not necessary to provide a region where the light emitting layer 1a and the first conductive type semiconductor layer 1b are not formed in the second conductive type semiconductor layer 1c and to form the conductive layer 3 in this region. The area with the light extraction portion of the photoconductive layer 7 can be increased, and as a result, good emission intensity can be obtained. Further, it is possible to eliminate the step of providing a region where the light emitting layer 1a and the first conductivity type semiconductor layer 1b are not formed in the second conductivity type semiconductor layer 1c, and the manufacturing becomes simple.

  Further, the base 9 may be bonded on the conductive reflective layer 8. The substrate 9 can be made of the same material as that of the light emitting element shown in FIG. 1 and has the same function and effect. In this case, it is desirable to use a conductive material. By using the base 9 having conductivity, electrical connection can be established from the mounting substrate side on which the light emitting element is mounted to the gallium nitride compound semiconductor layer 1 via the base 9 and the conductive reflective layer 8. It can be easy.

  The light-emitting element of the present invention shown in FIG. 1 and FIG. 2 has the above-described configuration on the light-transmitting conductive layer 2 or the light-transmitting conductive layer 7 or the light-transmitting conductive layer 2 or the light-transmitting layer. An antireflection layer (not shown) may be formed between the conductive conductive layer 7 and the gallium nitride compound semiconductor layer 1.

The antireflection layer is formed on the translucent conductive layer 2 or the translucent conductive layer 7 or between the translucent conductive layer 2 or the translucent conductive layer 7 and the gallium nitride compound semiconductor layer 1. For example, a dielectric such as quartz (SiO ₂ ), alumina (Al ₂ O ₃ ), or polycarbonate may be formed in a single layer or multiple layers. In this case, the refractive index is gradually decreased from the gallium nitride-based compound semiconductor layer 1 side, or the film thickness of the antireflection layer is changed to the wavelength in the antireflection layer of ultraviolet to near ultraviolet light generated in the light emitting layer 1a. What is necessary is just to make it become about 1/4. As a result, the multiple reflected lights in the antireflection layer weaken each other and easily interfere with each other, and a standing wave is less likely to be generated.

  When the antireflection layer is provided as described above, the antireflection layer causes the ultraviolet to near ultraviolet light generated inside the gallium nitride compound semiconductor layer 1 to be reflected in the reflection layer 5 of the gallium nitride compound semiconductor layer 1 or conductive reflection. Since the light can be transmitted without reflecting to the surface side on which the layer 8 is formed, the light attenuated by multiple reflection inside the gallium nitride-based compound semiconductor layer 1 is reduced, and the light-transmitting conductive layer 2 or the light-transmitting conductive layer 2 is transmitted. Since light can be efficiently extracted to the photoconductive layer 7 side, the light extraction efficiency can be further improved. Further, since such an antireflection layer can be provided without using epitaxial growth, there is an advantage that various materials and manufacturing processes used for the antireflection layer can be selected from an optical standpoint. The light-reflecting conductive layer 2 or the light-transmitting conductive layer 7 that is the light extraction surface can be efficiently irradiated with light having a suitable refractive index, surface shape, etc. Can be taken out.

  In addition, for example, a large number of protrusions whose top portion is smaller than the base portion or a large number of depressions whose bottom portion is smaller than the opening portion may be formed on the main surface. Specifically, the structure of the protrusion or the depression of the antireflection layer may be a polygonal pyramid shape or a conical shape. Note that the polygonal pyramid or conical shape includes a polygonal pyramid or a cone having a curved surface having no inflection point in an arbitrary cross section in addition to the polygonal pyramid and the cone. Moreover, it is good also as what made the top part planar shape with respect to either a polygonal pyramid shape or a cone shape. Further, the protrusion or depression of the antireflection layer may be hemispherical. The hemispherical shape includes not only a hemisphere but also a slope whose hemisphere has a curved line having no inflection point in an arbitrary cross section. In addition, the width of the base or opening is set to be not more than 1 times the wavelength in the antireflection layer of ultraviolet to near ultraviolet light generated in the light emitting layer 1a, and the height from the base to the top or from the opening to the bottom is 1 It should be more than double.

  Such protrusions or depressions may be formed by etching using a photolithography technique and a dry or wet etching technique. What is necessary is just to form as many such protrusions or depressions as possible with no gap with respect to the surface of the antireflection layer.

  When such an antireflection layer is formed between the translucent conductive layer 2 or the translucent conductive layer 7 and the gallium nitride compound semiconductor layer 1, one main surface 1b1 of the gallium nitride compound semiconductor layer 1 is used. By etching the side surface using photolithography and dry etching or wet etching, the above-described protrusions or depressions are formed on a part of the gallium nitride compound semiconductor layer 1 (a part of the first conductivity type semiconductor layer 1b). It may be formed. At this time, when the gallium nitride-based compound semiconductor layer 1 is viewed in the thickness direction, the portion where the projections or depressions are formed is used as the antireflection layer.

  When the antireflection layer has such protrusions or depressions, the incident angle of light incident on the surface of the protrusions or depressions can be reduced even when the protrusions or depressions enter the antireflection layer from an oblique direction. Since it functions to prevent reflection by making it larger than the critical angle, light incident from an oblique direction can be transmitted to the antireflection layer. Therefore, since the range of the incident angle of light with respect to the antireflection layer that can be transmitted through the antireflection layer can be widened, the light extraction efficiency can be further improved.

Next, an example of an embodiment of the method for manufacturing a light emitting element of the present invention will be described below. On the main surface of the substrate 4 made of a diboride single crystal represented by the chemical formula XB ₂ (where X includes at least one of Ti and Zr), the chemical formula Ga _{1-x′-y ′} In _{y ′} A buffer layer (not shown) made of a gallium nitride compound semiconductor represented by Al _{x ′} N (where 0 <x ′ + y ′ <1, x ′> 0, y ′ ≧ 0); a second conductive semiconductor layer 1c made of the same composition as the buffer layer, the chemical formula _{Ga 1-x "-y" In} y "Al x" N ( However, 0 <x "+ y"<1, x "> 0, y A light emitting layer 1a made of a gallium nitride compound semiconductor represented by “≧ 0” and a chemical formula Ga _1-xy In _y Al _x N (where 0 <x + y <1, x> 0, y ≧ The first conductivity type semiconductor layer 1b made of a gallium nitride compound semiconductor represented by Epitaxial growth (where x, x ′> x ″, y, y ′ ≦ y ″), a step of forming the translucent conductive layer 2 on the first conductivity type semiconductor layer 1b, In this configuration, the substrate 4 is removed from the buffer layer while the photoconductive layer 2 is protected, and the reflective layer 5 is formed on the surface of the buffer layer from which the substrate 4 is removed. Further details are as follows.

  FIGS. 3A to 3G are cross-sectional views showing respective steps of the first light emitting device manufacturing method of the present invention. The gallium nitride compound semiconductor layer 1 including the light emitting layer 1a on the substrate 4 is shown in FIGS. The step of epitaxial growth, the step of forming the light-transmitting conductive layer 2 on the gallium nitride-based compound semiconductor layer 1, and the substrate 4 is removed from the gallium nitride-based compound semiconductor layer 1 while protecting the light-transmitting conductive layer 2 And a step of forming the reflective layer 5 on the surface of the gallium nitride compound semiconductor layer 1 from which the substrate 4 has been removed.

Specifically, as shown in FIG. 3A, a gallium nitride-based compound semiconductor layer 1 is formed on a substrate 4 made of, for example, zirconium boride (ZrB ₂ ) single crystal as a diboride single crystal. Epitaxial growth is performed by a growth (MOCVD) method. As the gallium nitride compound semiconductor layer 1, the same composition as the buffer layer is formed on the substrate 4 through a buffer layer (not shown) made of Ga _{1-x ′} Al _{x ′} N (where 0 <x ′ <1). Second conductive semiconductor layer 1c, a light emitting layer 1a made of Ga _{1-x ″} Al _{x ″} N (where 0 <x ″ <1), and Ga _1-x Al _x N (where 0 <x < The first conductive semiconductor layer 1b made of 1) is formed in order.

More specifically, the buffer layer and the gallium nitride compound semiconductor layer 1 were produced as follows. The buffer layer has a substrate 4 temperature of 400 to 950 ° C., which is a relatively low temperature, and aluminum gallium nitride (Ga _{1-x ′} Al _{x ′} N, 0 <x ′ <1) on the substrate 4 is 20 to 300 nanometers. What is necessary is just to produce with the thickness of a meter (nm) grade.

The second conductive semiconductor layer 1c is aluminum gallium nitride having the same composition as the buffer layer on the buffer layer _{(Ga 1-x 'Al x} ' N, 0 <x '<1) The number micrometers ([mu] m ) To a thickness (for example, 1 to 5 μm). At that time, the buffer layer side of the second conductivity type semiconductor layer 1c is grown at a relatively low temperature of 400 to 950 ° C., and thereafter grown at a relatively high temperature of 950 to 1150 ° C. At this time, since a current hardly flows between the conductive reflective layer 2 and the conductive layer 3 in the layer of the second conductive type semiconductor layer 1c grown at a relatively low temperature, a dopant is not necessarily required. Further, aluminum gallium nitride is preferable when x ′ = 0.26 in the above chemical formula (Ga _0.26 Al _0.76 N) because the lattice constant is best matched with the zirconium boride (ZrB ₂ ) single crystal.

Further, as the light emitting layer 1a, for example, the substrate 4 temperature is set to about 700 ° C. on the second conductive type semiconductor layer 1c, and the aluminum nitride gallium nitride (Ga _{1-x ″} Al _{x ″} N, A layer consisting of x ″ <x ′) is formed.

As the first conductive semiconductor layer 1b, for example, the temperature of the substrate 4 is set to 700 to 1050 ° C., and aluminum nitride / gallium nitride (Ga _1-x Al _x N, x> x ″) is 0.1 to on the light emitting layer 1a. It is formed with a thickness of about 2 μm.

  Next, as shown in FIG. 3B, a translucent conductive layer 2 is formed on one main surface 1b1 of the gallium nitride compound semiconductor layer 1 by a vacuum deposition method or a sputtering method. Further, an electrode pad 6 is formed on a part of the translucent conductive layer 2 by vacuum deposition or sputtering.

  Next, as shown in FIG. 3C, a part of the light-transmitting conductive layer 2 and the gallium nitride compound semiconductor layer 1 is etched until the surface of the second conductivity type semiconductor layer 1c is exposed, The step of forming the conductive layer 3 is performed. In addition, a light emitting layer 1a and a first conductive type semiconductor layer 1b are formed on the second conductive type semiconductor layer 1c by forming a mask at a portion where the conductive layer 3 is formed after the second conductive type semiconductor layer 1c is formed. A region not formed may be provided, and the conductive layer 3 may be formed in that region. Thus, by forming the conductive layer 3, when the light-emitting element is mounted on a mounting substrate or the like, the translucent conductive layer 2 and the conductive layer 3 are formed in the same direction, so that mounting is possible. It becomes easy. Note that the conductive layer 3 may be formed before forming the translucent conductive layer 2.

  Next, in the step of removing the substrate 4 from the gallium nitride compound semiconductor layer 1 in a state where the top of the translucent conductive layer 2 is protected, first, as shown in FIG. After covering the conductive layer 3 with the protective film 10, the substrate 4 is removed as shown in FIG. At this time, in order to remove the substrate 4, a chemical or physical method can be used according to the material of the substrate 4. In the present invention, when the substrate 4 is made of zirconium boride, the substrate 4 can be easily removed from the gallium nitride compound semiconductor layer 1 or the buffer layer by chemically etching the substrate 4 using an acid as an etchant. Can do. In addition, when the substrate 4 is made of sapphire, the interface between the substrate 4 and the gallium nitride compound semiconductor layer 1 is irradiated with a laser beam having a wavelength of about 370 nm to melt a part of the gallium nitride compound semiconductor layer 1. Then, the substrate 4 may be detached.

  Further, the protective film 10 may be formed of a material that can withstand the process of removing the substrate 4 and may be formed, for example, by spin coating an inorganic or organic coating material.

  Next, as shown in FIG. 3F, the reflective layer 5 is formed on the surface of the gallium nitride compound semiconductor layer 1 from which the substrate 4 has been removed by a vacuum deposition method, a sputtering method, or the like.

  Next, as shown in FIG. 3G, the base 9 is bonded to the surface of the reflective layer 5 that is not in contact with the gallium nitride compound semiconductor layer 1. Bonding of the base body 9 is preferably performed by a pressure bonding method, a brazing method, a method of applying an adhesive, and bonding. In this case, the gallium nitride compound semiconductor layer 1 can be mechanically strengthened by the substrate 9.

  Finally, the protective film 10 was removed by, for example, a dry etching technique (dry etching) to manufacture the light emitting device of the present invention. Further, the substrate 9 may be bonded after the protective film 10 is removed.

  According to the method for manufacturing the light emitting device of the present invention shown in FIG. 3, the light-transmitting conductive layer 2 is protected in the step of removing the substrate 4 from the gallium nitride compound semiconductor layer 1, so that the gallium nitride system is protected. The surface of the compound semiconductor layer 1 and the translucent conductive layer 2 and the electrode pad 6 formed thereon can be protected from contamination and corrosion caused by, for example, an etching solution, and the gallium nitride compound semiconductor layer 1 can be machined. Therefore, a high-performance light-emitting element can be reliably manufactured.

  Further, since a boride single crystal is used for the substrate 4, the lattice constant of the substrate 4 made of the boride single crystal and the gallium nitride compound semiconductor layer 1 are matched, so that the gallium nitride compound semiconductor having good crystal quality is obtained. Since the layer 1 can be formed, a high-performance light-emitting element can be more reliably manufactured.

  Next, an example of an embodiment of the lighting device of the present invention will be described below. The light-emitting element according to the present invention having the above-described structure and at least one of a phosphor and a phosphor that emit light upon receiving light emitted from the light-emitting element are provided. According to such an illumination device of the present invention, the phosphor or phosphor is strongly excited by the light of the light emitting element having a good light emission intensity with a small power, so that a good illuminance can be obtained with a small power. It becomes. In addition, such an illumination device of the present invention is superior in energy saving and downsizing than conventional fluorescent lamps and discharge lamps, and is superior to fluorescent lamps and discharge lamps.

  Thus, according to the present invention, the light extraction efficiency of ultraviolet light is greatly improved, and as a result, a high-performance light-emitting element capable of obtaining good light emission intensity with low power and the high-performance light-emitting element are surely obtained. A manufacturing method of a light-emitting element that can be manufactured and a lighting device using the high-performance light-emitting element can be provided.

  In addition, this invention is not limited to the example of the above embodiment, A various change and improvement can be performed in the range which does not deviate from the summary of this invention. For example, the reflective layer 5 may transmit part of the light emitted from the light emitting layer 1a with a transmittance of about 1%, for example, and reflect other light. In this case, by monitoring the intensity and wavelength of the light transmitted through the reflective layer 5, the emission intensity and the like can be controlled using the monitored result.

It is typical sectional drawing which shows an example of embodiment of the light emitting element of this invention. It is typical sectional drawing which shows the other example of embodiment of the light emitting element of this invention. (A)-(g) is typical sectional drawing for every process which shows the manufacturing method of the light emitting element of this invention, respectively. (A)-(c) is sectional drawing which shows the prior art example of the 1st-3rd light emitting element, respectively.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Gallium nitride type compound semiconductor layer 1a ... Light emitting layer 1b ... 1st conductivity type semiconductor layer (p-type semiconductor layer)
1b1... One main surface 1c... Second conductivity type semiconductor layer (n-type semiconductor layer)
1c1 ... other main surface 2 ... translucent conductive layer 3 ... conductive layer 4 ... substrate 5 ... reflective layer 6 ... electrode pad 7 ... translucent conductive layer 8. ..Conductive reflective layer 9 ... Substrate
10 ... Protective film

Claims (3)

A first conductivity type semiconductor layer made of a gallium nitride compound semiconductor represented by the chemical formula Ga _1-xy In _y Al _x N (where 0 <x + y <1, x> 0, y ≧ 0); A gallium nitride compound represented by the chemical formula Ga _{1-x′-y ′} In _{y ′} Al _{x ′} N (where 0 <x ′ + y ′ <1, x ′> 0, y ′ ≧ 0). Between the second conductivity type semiconductor layer made of a semiconductor, the chemical formula Ga _{1-x ″ -y ″} In _{y ″} Al _{x ″} N (where 0 <x ″ + y ″ <1, x ″> 0, y ″ ≧ 0.) A gallium nitride compound semiconductor layer formed by sandwiching a light emitting layer composed of a gallium nitride compound semiconductor (where x, x ′> x ″, y, y ′ ≦ y ″) And a semiconductor layer on the other main surface side of the gallium nitride compound semiconductor layer. A substrate used for epitaxial growth of the gallium nitride compound semiconductor layer is removed from the other main surface of the gallium nitride compound semiconductor layer. A light-emitting element, wherein a reflective layer is formed on a surface side. On the main surface of the substrate made of a diboride single crystal represented by the chemical formula XB ₂ (wherein X includes at least one of Ti and Zr), the chemical formula Ga _{1-x′-y ′} In _{y ′} A buffer layer made of a gallium nitride compound semiconductor represented by Al _{x ′} N (where 0 <x ′ + y ′ <1, x ′> 0, y ′ ≧ 0), and the same composition as the buffer layer a second conductive type semiconductor layer of the formula _{Ga 1-x "-y" in} y "Al x" N ( provided, however, that 0 <x "+ y"< 1, x "> 0, y" ≧ 0.) a light emitting layer made of gallium nitride-based compound semiconductor represented in, represented by the chemical formula _{Ga 1-x-y in y} Al x N ( where the 0 <x + y <1, x> 0, y ≧ 0.) A step of epitaxially growing a first conductive semiconductor layer made of a gallium nitride compound semiconductor However, x, x ′> x ″, y, y ′ ≦ y ″), a step of forming a translucent conductive layer on the first conductive type semiconductor layer, and on the translucent conductive layer A method of manufacturing a light emitting device, comprising: removing the substrate from the buffer layer in a state where the substrate is protected; and forming a reflective layer on the surface of the buffer layer from which the substrate is removed. An illuminating device comprising: the light-emitting element according to claim 1; and at least one of a phosphor and a phosphor that emit light upon receiving light emitted from the light-emitting element.

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