200536142 玖、發明說明 【發明所屬之技術領域】 本發明是有關於一種氮化鎵系發光二極體之製造 方法與結構，且特別是一種可提高發光亮度，以及具 有靜電放電防護之氮化鎵系發光二極體的製作方法與 結構。 【先前技術】 發光二極體（Light Emitting Diode ; LED)因具有生 產成本低、結構簡單、低耗電、體積小以及安裝容易 之優勢，而大量運用於照明光源以及顯示器技術中。 其中’又以類屬氮化鎵系（Galliuni Nitrid卜based ; GaN-based)的發光元件，例如氮化鎵（GaN)藍光發光二 極體，在近幾年的發光元件市場中，甚受重視。 一般的氮化鎵系發光二極體，基於氮化鎵系膜層 之結晶品質的考量，大多選用藍寶石（sapphire)材質作 為基板。然而，由於藍寶石係為一絕緣材料，因此， 使得元件中的陽極電極與陰極電極須製作於藍寶石基 板的同一面上，而導致電流傳送時，容易於陰極附近 發生電流擁擠（current crowding)的現象，使操作電阻 增加，以致降低了光輸出的效率。 另外，藍寶石的絕緣性質，亦無法對於元件製作 中產生的靜電累積，提供有效的導通釋放，因此極容 易導致靜電放電（Electro-Static Discharge ; ESD)的問 200536142 題發生，而對元件造成損壞。同時，因為藍寶石材質 的散熱性不佳，亦會導致元件運作過熱的現象產生，而 降低了發光元件之運作效能。 除此之外’元件之亮度提升’是目前發光二極體 技術的主要發展趨勢，但是，由於藍寶石基材會部分 吸收元件之發光，且對於元件之發光所具有的反射率 極低，例如對藍光的反射率約只有2%〜7%。因此，氮 化鎵系發光元件的光輸出強度係完全取決於二極體本 身的發光特性，而無法另外將二極體發出的光作有效 地利用’以使元件的光輸出強度獲得提升。 【發明内容】 本發明之目的之一是在提供一種氮化鎵系 (GaN-based)發光二極體之製作方法與結構，不但可以改 善兀件内的電流分散情形，以提升發光二極體的光輸出效 率，更利用對7G件之發光的有效利用，而大幅增強光輸出 的強度，進而提高元件的品質與亮度呈現。 曰另外，本發明之另一目的，亦可降低元件内的靜電累 積里，以有效避免靜電放電的問題發生，而減少靜電對元 件造成之損害。 根據本發明之上述目❸，提出一種氮化鎵系發光二極 體之I作方法與結構。依照本發明之方法係為在基板上先 形成至J 一氮化鎵系發光元件，其中，氮化鎵系發光元件 有第電性氮化鎵系半導體層、發光主動層、第二 200536142 電性氮化鎵系半導體層、透明導電層、第一電性電極與第 一電性電極，而基板則例如為藍寳石基材，以獲得結晶品 質良好的氮化鎵系半導體層。接著，貼附一暫時載體於氮 化鎵系發光元件之上，且暫時載體與氮化鎵系發光元件之 間，係包含一用以接合暫時載體與氮化鎵系發光元件之黏 膠層。然後，將基板移除，以完整暴露出氮化鎵系發光元 件之第一電性氮化鎵系半導體層。 接著，再依序形成一反射層與金屬基材層於第一電性 氮化鎵系半導體層之上，最後，將暫時載體與黏膠層同時 移除，而完成具有金屬導電基板的氮化鎵系發光二極體。 其中，氮化鎵系發光元件例如可為氮化鎵（GaN)二極 體，而反射層係選用對藍紫綠光具有高反射特性之金屬材 質’例如銀（Ag)或鋁（A1)，可反射氮化鎵系二極體之部分 發光，以提高氮化鎵系元件之光輸出強度。另外，金屬基 材層則為具有良好導電特性之金屬材質，例如銀或銅 (Cu) ’可&供為元件内電流分散的流通路徑，而提升電流 分散的成效，減少電流擁擠的現象，並降低元件的操作電 阻’進而增加元件的光輸出效率。 同時’對於一些在製程進行中產生於元件内的靜電累 積蓋’更可藉由具導電特性之金屬基材層而予以導通釋 放’以有效避免靜電放電的問題發生。除此之外，通常導 電金屬基材亦具有良好的熱傳性，因此，有助於增加元件 的散熱性’而提供發光元件操作時極佳的散熱效果，以保 有元件的運作效能。 200536142 因此，應用本發明之氮化鎵系發光二極體的製作方 法，除了以反射層之設置，對元件内部之發光作有效之利 用，而大幅提升元件的光輸出強度之外，更利用將基板置 換為導電性佳的金屬基材，而改善元件内的電流分散成 效，以使元件之操作電阻降低，並進而提升元件之光輸出 效率。另外，因元件内靜電累積而導致靜電放電傷害之問 題，亦可藉由導電性金屬基材而有效避免。故藉由本發明 之方法所製作的氮化鎵系發光二極體，不僅因光輸出強度 以及光輸出效率之增加，而大幅提升了元件的亮度，同 時，更因降低了元件受靜電放電傷害之機率，而增加了氮 化鎵系發光元件製作之產品良率與可靠度。 【實施方式】 本發明係k供一種氮化録系（GaN-based)發光二極體 之製作方法與結構，以轉移基板之技術，將製作於藍寶石 基材上的氮化鎵系發光二極體，移轉至金屬基板上，藉由 金屬基板的導電性’以提供元件良好的電導通作用，進而 提升元件内的電流分散效果，並降低元件内的靜電累積 量。同時，於金屬基板與氮化鎵系發光二極體之間，設置 有一反射層，利用反射層對光所具有的高反射特性，以使 二極體之發光，可有效地被反射而成為光輸出的另一來 源’進而提高元件之光輸出強度。以下將以實施例對本發 明之方法加以詳細說明。 200536142 實施例 本發明揭露了一種氮化鎵（GaN)發光二極體之製作方 法與結構。依序參照第1A〜1E圖，第ία〜1E圖係為依照 本發明較佳實施例之一種氮化鎵發光二極體製作方法的 流程剖面示意圖。 在第1A圖中，首先製作一具有基板丨00的氮化鎵二 極體元件110，其中，基板1〇〇例如選用藍寶石（sapphire) 材質，以獲得結晶品質良好的氮化鎵半導體層，而氮化鎵 一極體元件11 〇的製作，首先係分別依序形成一 η型氮化 鎵半導體層102, 一具有多層量子井（Multi_Quantum WeU) 結構之發光主動層1〇4，以及一 p型氮化鎵半導體層ι〇6 於基板100之上。接著，在p型氮化鎵半導體層ι〇6之上， 形成一透明導電層108，以提供電流分散（current spreading)之作用，透明導電層1〇8的材質則例如可為銦 錫氧化物（Indium-Tin Oxide ; ITO)或銦鋅氧化物 (Indium-Zinc 〇xide ; IZO)。然後，分別在透明導電層1〇8 以及η型氮化鎵半導體層1〇2之部分表面上，形成陽極電 極112與陰極電極1丨4。 接著，參照第1 B圖，利用一黏膠層11 ό ,先將製作 於基板1 00上的氮化鎵二極體元件110，整個結構倒置地 貼附於一暫時載體12〇之上。其中，黏膠層116例如可使 用環氧樹脂（epoxy)或瞬間接著膠。然後，將基板1〇〇移 除’以暴露出完整的n型氮化鎵半導體層1〇2，如第ic 圖所不，而移除基板丨00的方法則例如可採用雷射剝離 200536142 (laser lift-off)或是研磨技術。 參照第ID圖，在移除基板1〇〇之後，以接合的方 式，依序形成一反射層130以及一金屬基材層 型氮化鎵半導體層之上，其中，反射層丨3〇係選用對紫藍 綠光波長範圍之發光具有高反射率的金屬材質，例如可為 銀（Ag)、鋁（A1)、鎳（Ni)、鈀（Pd)或鉬（Mo)，尤其是銀或 紹具有的反射率約達85%〜90%。金屬基材層140則選用 導電性佳的金屬材質，例如可為銀或銅（Cu)，且金屬基材 層140的厚度明顯大於反射層13〇的厚度，以提供作為支 撐氮化鎵發光二極體的導電性基板。 最後，再將黏膠層116移除，以同時分離暫時載體 120，而形成一具有金屬基材層14〇的氮化鎵二極體元件 150，如第1E圖所示。氮化鎵二極體元件15〇，係以具有 良好導電性的金屬基材層14〇作為承載基板。 在第1E圖中，由於反射層13〇具有的高反射特性， 可使元件内的發光，除了一部份直接向上輸出之外，另一 部份朝向金屬基材層14〇發出的光，則藉由反射層13〇 的反射作用，而提供成為向上輸出的光源，使元件内的發 光能被有效地再次利用，以增加元件可達成的光輸出強 度。 另外，可藉由金屬基材層140所提供的良好導電特 性，而使元件内的電流傳遞，由陽極電極112的位置，往 下刀政時，先流經金屬基材層丨4 〇，再往陰極電極114的 位置傳送，如此，可形成電阻並聯降低阻值的效應，並改 200536142 善當陰極電極112與陽極電極114製作於同一平面 易產生於η型氮化鎵半導體層1〇2附近的電流擁擠 (瞻_ Gr°Wding)現象，因而，有效降低元件的操作電 阻’進而提南元件的光輸出效率。 除此之外，對於-些在製程進行中產生於元件内的靜 電累積量’更可藉由具導電特性之金屬基材層“Ο而獲得 導通釋放，以有效避免靜電放電 祕咖則)的問題發生，進而降低元件受損的機率。 另外，由於反射層U0選用之金屬材質亦具有導電特 性，故亦可於氮化鎵二極體結構製作時（如第丨A圖所 不），先不製作陰極電極114,而於基板轉移完成之後， 移除部分之η型氮化鎵半導體層1〇2，再將陰極電極ιΐ4 製作於反射層130之上，完成如第2圖所示之另一發光二 極體結構，則元件内之電流傳送情形，即為電流傳遞路徑 220所表示。如此，更可有效避免電流擁擠現象發生於η 型氣化鎵半導體層102之位置。又或者是亦可將陰極電極 114直接製作在金屬基材層140之下方，以形成垂直電流 之電流分佈情形，而大幅提昇電流分散之成效。 根據上述本發明之實施例可知，應用本發明之氮化鎵 發光二極體的製作方法，可在不影響一般元件的製作條件 下’利用元件基板轉移的技術，將原本的絕緣性基板，轉 換為導電性佳的金屬基板，以同時提高元件内電流傳遞分 散的效率，並降低靜電放電的危害產生，進而提升氮化鎵 元件的光輸出效率以及元件製造的產品良率。另外，通常 200536142 導電金屬基材亦具有良好的熱傳性，因此，有助於增加元 件的政熱性’而提供發光元件操作時極佳的散熱效果，以 保有元件的運作效能。 本發明亦利用反射層，對氮化鎵元件之發光具有高反 射的能力’以使元件内的發光可有效地被利用，將原本非 直接向外輸出的部分發光，經由反射層的反射作用，而轉 換成為元件實際之輸出光源的一部份，因此大幅增加了氮 化鎵7G件的光輸出強度，進而提升元件的亮度呈現。 本發明不只侷限於使用在氮化鎵發光二極體的技術 上，其他所有屬於氮化鎵系發光二極體元件之製作，例如 氮化錮鎵（InGaN)發光二極體或氮化鋁鎵（A1GaN)紫外光 發光一極體，亦可藉由本發明之方法製作，而大幅提升產 品的特性。 雖然本發明已以實施例揭露如上’然其並非用以限 定本發明，任何熟習此技藝者，在不脫離本發明之精神和 範圍内，當可作各種之更動與料，因此本發明之保護範 圍當視後附之申請專利範圍所界定者為準。 【圖式簡單說明】 為讓本發明之上述特徵、方法 Θ t 目的及優點能更明顯 易懂，配合所附圖式，加以說明如下： 苐1A〜1E圖係為依照本發明較佳眚 π权住貫施例之一種氮化 鎵發光二極體製作方法的流程剖面示意圖。 第2圖係為依照本發明較佳實施利之另一氮化鎵發 13 200536142 光二極體結構示意圖。 【元件代表符號簡單說明】 100 :基板 102、106 :氮化鎵半導體層 104 :主動層 108 :透明導電層 110、150 :二極體元件 11 2、114 :電極 11 6 :黏膠層 120 :載體 130 :反射層 1 40 :金屬基材層 14200536142 发明. Description of the invention [Technical field to which the invention belongs] The present invention relates to a method and structure for manufacturing a gallium nitride-based light emitting diode, and more particularly to a gallium nitride capable of improving light emission brightness and having electrostatic discharge protection. Manufacturing method and structure of light emitting diode. [Previous Technology] Light Emitting Diodes (LEDs) are widely used in lighting sources and display technologies due to their advantages of low production cost, simple structure, low power consumption, small size, and easy installation. Among them, Galliuni Nitrid-based (GaN-based) light-emitting devices, such as gallium nitride (GaN) blue light-emitting diodes, have received much attention in the light-emitting device market in recent years. . Generally, GaN-based light-emitting diodes are based on the crystalline quality of the GaN-based film, and most of them use sapphire as the substrate. However, because sapphire is an insulating material, the anode and cathode electrodes in the element must be made on the same side of the sapphire substrate. As a result, current crowding is easy to occur near the cathode when the current is transmitted. , So that the operating resistance is increased, so that the efficiency of light output is reduced. In addition, the sapphire's insulating properties can not provide effective conduction release for the static electricity generated during the production of components, so it is very easy to cause the problem of Electrostatic Discharge (ESD) 200536142 and damage the components. At the same time, the poor heat dissipation of the sapphire material will also lead to overheating of the component operation, which will reduce the operating efficiency of the light-emitting component. In addition, the “brightness enhancement of the element” is the main development trend of the current light-emitting diode technology. However, because the sapphire substrate partially absorbs the light emission of the element and has a very low reflectivity for the light emission of the element, for example, the The reflectance of blue light is only about 2% ~ 7%. Therefore, the light output intensity of the gallium nitride-based light-emitting element depends entirely on the light-emitting characteristics of the diode itself, and it is not possible to effectively utilize the light emitted by the diode 'to increase the light output intensity of the element. [Summary of the Invention] One of the objectives of the present invention is to provide a method and structure for manufacturing a GaN-based light emitting diode, which can not only improve the current dispersion in the element, but also improve the light emitting diode. The light output efficiency is more effective by making effective use of the light emission of 7G parts, which greatly enhances the intensity of light output, thereby improving the quality and brightness of components. In other words, another object of the present invention is to reduce the accumulation of static electricity in the element, so as to effectively avoid the problem of electrostatic discharge, and reduce the damage caused to the element by static electricity. According to the above purpose of the present invention, a method and a structure of a gallium nitride based light emitting diode are proposed. The method according to the present invention is to first form a J-gallium nitride-based light-emitting element on a substrate, wherein the gallium nitride-based light-emitting element has a first electrical gallium nitride-based semiconductor layer, a light-emitting active layer, and a second 200536142 electrical property. The gallium nitride-based semiconductor layer, the transparent conductive layer, the first electrical electrode and the first electrical electrode, and the substrate is, for example, a sapphire substrate to obtain a gallium nitride-based semiconductor layer with good crystal quality. Then, a temporary carrier is attached on the gallium nitride-based light-emitting device, and the temporary carrier and the gallium nitride-based light-emitting device include an adhesive layer for bonding the temporary carrier and the gallium nitride-based light-emitting device. Then, the substrate is removed to completely expose the first electrical gallium nitride based semiconductor layer of the gallium nitride based light emitting device. Next, a reflective layer and a metal substrate layer are sequentially formed on the first electrical gallium nitride-based semiconductor layer. Finally, the temporary carrier and the adhesive layer are removed at the same time to complete the nitriding of the metal conductive substrate. Gallium based light emitting diode. Among them, the gallium nitride-based light-emitting element may be, for example, a gallium nitride (GaN) diode, and the reflective layer is made of a metal material having high reflection characteristics for blue-violet-green light, such as silver (Ag) or aluminum (A1), A part of the GaN-based diode can be reflected to increase the light output intensity of the GaN-based device. In addition, the metal substrate layer is a metal material with good conductive properties, such as silver or copper (Cu), which can be used as a current distribution path in the element to improve the effectiveness of current dispersion and reduce the phenomenon of current crowding. And reduce the operating resistance of the element, thereby increasing the light output efficiency of the element. At the same time, 'for some electrostatic accumulation caps generated in the element during the process', it can be conducted and released through the metal substrate layer with conductive properties' to effectively avoid the problem of electrostatic discharge. In addition, usually conductive metal substrates also have good thermal conductivity. Therefore, it helps to increase the heat dissipation of the element 'and provides excellent heat dissipation effect during the operation of the light-emitting element to maintain the operation efficiency of the element. 200536142 Therefore, in addition to the manufacturing method of the gallium nitride-based light emitting diode using the present invention, in addition to the use of a reflective layer, the light emission inside the element is effectively used, and the light output intensity of the element is greatly improved. The substrate is replaced with a metal substrate with good conductivity, and the current dispersion effect in the device is improved, so that the operating resistance of the device is reduced, and the light output efficiency of the device is further improved. In addition, the problem of electrostatic discharge damage due to the accumulation of static electricity in the element can also be effectively avoided by the conductive metal substrate. Therefore, the gallium nitride-based light-emitting diode manufactured by the method of the present invention not only greatly increases the brightness of the device due to the increase in light output intensity and light output efficiency, but also reduces the damage caused by the electrostatic discharge of the device. Probability, which increases the yield and reliability of GaN-based light-emitting device production. [Embodiment] The present invention provides a method and structure for manufacturing a GaN-based light-emitting diode, and a GaN-based light-emitting diode fabricated on a sapphire substrate will be manufactured by transferring the substrate technology. The body is transferred to the metal substrate, and the electrical conductivity of the metal substrate is used to provide a good electrical conduction effect of the element, thereby improving the current dispersion effect in the element and reducing the amount of static electricity accumulated in the element. At the same time, a reflective layer is provided between the metal substrate and the gallium nitride-based light-emitting diode. The reflective layer has a high reflection characteristic for light, so that the light-emitting diode can be effectively reflected into light. Another source of output 'further increases the light output intensity of the device. The method of the present invention will be described in detail in the following examples. 200536142 Examples The present invention discloses a method and structure for manufacturing a gallium nitride (GaN) light emitting diode. Figures 1A to 1E are sequentially referred to, and Figures 1 to 1E are schematic cross-sectional views of the flow of a method for manufacturing a gallium nitride light emitting diode according to a preferred embodiment of the present invention. In FIG. 1A, a gallium nitride diode element 110 having a substrate 00 is first fabricated. The substrate 100 is made of sapphire, for example, to obtain a gallium nitride semiconductor layer with good crystal quality, and The fabrication of a gallium nitride monopolar element 110 is firstly sequentially forming an n-type gallium nitride semiconductor layer 102, a light-emitting active layer 104 having a multilayer quantum well (Multi_Quantum WeU) structure, and a p-type A gallium nitride semiconductor layer 106 is formed on the substrate 100. Next, a transparent conductive layer 108 is formed on the p-type gallium nitride semiconductor layer 106 to provide a current spreading effect. The material of the transparent conductive layer 108 may be, for example, indium tin oxide. (Indium-Tin Oxide; ITO) or Indium-Zinc Oxide (IZO). Then, an anode electrode 112 and a cathode electrode 1-4 are formed on a part of the surface of the transparent conductive layer 108 and the n-type gallium nitride semiconductor layer 102, respectively. Next, referring to FIG. 1B, using an adhesive layer 11th, the gallium nitride diode element 110 fabricated on the substrate 100 is firstly attached to a temporary carrier 12o. Among them, the adhesive layer 116 can be, for example, epoxy or instant adhesive. Then, the substrate 100 is removed to expose a complete n-type gallium nitride semiconductor layer 102, as shown in FIG. Ic, and the method of removing the substrate 00 may be, for example, laser peeling 200536142 ( laser lift-off) or grinding technology. Referring to FIG. ID, after the substrate 100 is removed, a reflective layer 130 and a metal substrate layer type gallium nitride semiconductor layer are sequentially formed in a bonding manner. Among them, the reflective layer 30 is selected Metal materials with high reflectivity for violet, blue and green wavelengths, such as silver (Ag), aluminum (A1), nickel (Ni), palladium (Pd) or molybdenum (Mo), especially silver or Shao Has a reflectivity of about 85% to 90%. The metal substrate layer 140 is made of a highly conductive metal material, such as silver or copper (Cu), and the thickness of the metal substrate layer 140 is significantly larger than the thickness of the reflective layer 130, so as to provide support for gallium nitride light-emitting diodes. Conductive substrate of a polar body. Finally, the adhesive layer 116 is removed to separate the temporary carrier 120 at the same time, and a gallium nitride diode device 150 having a metal substrate layer 14 is formed, as shown in FIG. 1E. The gallium nitride diode element 150 uses a metal base material layer 14 having good conductivity as a carrier substrate. In FIG. 1E, due to the high reflection characteristics of the reflective layer 13o, the light emitted in the element can be directly output upward, and the other part of the light emitted toward the metal substrate layer 14o, then Through the reflection effect of the reflective layer 13, a light source that provides upward output is provided, so that the light emission in the element can be effectively reused to increase the light output intensity that the element can achieve. In addition, due to the good conductivity provided by the metal substrate layer 140, the current in the element can be transferred from the position of the anode electrode 112 to the metal substrate layer first, and then pass through it. It is transmitted to the position of the cathode electrode 114. In this way, the effect of resistance parallel connection to reduce the resistance value can be formed. 200536142 Good when the cathode electrode 112 and the anode electrode 114 are manufactured on the same plane and are easily generated near the n-type gallium nitride semiconductor layer 102. The phenomenon of current congestion (see Gr_Wding), therefore, effectively reduces the operating resistance of the device, and further improves the light output efficiency of the device. In addition, for some of the accumulated static electricity generated in the component during the process, it can be achieved by the conductive base metal layer "0 to achieve conduction release, so as to effectively avoid electrostatic discharge.) Problems occur, which reduces the chance of damage to the component. In addition, because the metal material selected for the reflective layer U0 also has conductive properties, it can also be used in the fabrication of gallium nitride diode structures (as shown in Figure 丨 A). Instead of fabricating the cathode electrode 114, after the substrate transfer is completed, remove a part of the n-type gallium nitride semiconductor layer 102, and then fabricate the cathode electrode ι4 over the reflective layer 130, and complete another process as shown in FIG. 2 With a light-emitting diode structure, the current transfer situation in the element is represented by the current transfer path 220. In this way, the current crowding phenomenon can be effectively avoided at the position of the n-type gallium vaporized semiconductor layer 102. Or, The cathode electrode 114 can be fabricated directly under the metal substrate layer 140 to form a vertical current distribution situation, and the effect of current dispersion is greatly improved. According to the embodiment of the present invention, it can be known that By applying the manufacturing method of the gallium nitride light emitting diode of the present invention, the original insulating substrate can be converted into a metal substrate with good conductivity by using the technology of element substrate transfer without affecting the manufacturing conditions of ordinary components. At the same time, the efficiency of current transfer and dispersion in the element is improved, and the harm of electrostatic discharge is reduced, which further improves the light output efficiency of the gallium nitride element and the product yield of the element manufacturing. In addition, generally 200536142 conductive metal substrates also have good heat transfer. Therefore, it helps to increase the thermal performance of the element, and provides excellent heat dissipation effect during the operation of the light-emitting element, so as to maintain the operation efficiency of the element. The invention also uses a reflective layer, which has a high reflection of the light emission of the gallium nitride element. "Capacity" so that the light emission in the element can be effectively used, and the part that was originally not directly output to the outside is converted into a part of the actual output light source of the element through the reflection of the reflective layer, so the nitrogen is greatly increased. The light output intensity of the gallium gallium 7G element, thereby improving the brightness presentation of the element. The present invention is not limited to use In terms of the technology of gallium nitride light-emitting diodes, all other GaN-based light-emitting diode devices are manufactured, such as gallium gallium nitride (InGaN) light-emitting diodes or aluminum gallium nitride (A1GaN) ultraviolet light-emitting diodes. The polar body can also be produced by the method of the present invention, which greatly improves the characteristics of the product. Although the present invention has been disclosed in the above example, it is not intended to limit the present invention. Any person skilled in the art will not depart from the present invention. Within the spirit and scope, various changes and materials can be made, so the scope of protection of the present invention shall be determined by the scope of the appended patent application. [Brief description of the drawings] To make the above features and methods of the present invention Θ The purpose and advantages are more obvious and easy to understand. In conjunction with the attached drawings, the description is as follows: 苐 1A ~ 1E are a method for manufacturing a gallium nitride light emitting diode according to the preferred embodiment of the present invention. Process flow diagram. FIG. 2 is a schematic diagram of the structure of a photodiode according to another preferred embodiment of the present invention. [Simple description of element representative symbols] 100: substrate 102, 106: gallium nitride semiconductor layer 104: active layer 108: transparent conductive layer 110, 150: diode element 11 2, 114: electrode 11 6: adhesive layer 120: Carrier 130: Reflective layer 1 40: Metal substrate layer 14