1239665 九、發明說明： 【發明所屬之技術領域】 本發明係有關於一種氮化鎵系發光二極體，特別是有關一種表 面微粗化（Micro-roughened)的高亮度氮化鎵系發光二極體結 構。 【先前技術】 氮化鎵(GaN)系發光二極體，由於可以藉著控制材料的組成來製作出各 種色光的發光二極體，其相關技術因此成為近年來業界與學界積極研 發的焦點。學界與業界對氮化鎵系發光二極體的研究重點之一，係在 了解氮化鎵系發光二極體的發光特性，進而提出提升其發光效率與亮 度的做法。這種高效率與高亮度的氮化鎵系發光二極體，未來將可以 有效應用於戶外顯示看板、車用照明等領域。 氮化鎵系發光二極體的發光效率，主要和氮化鎵系發光二極體的内部 量子效率(Internal Quantum Efficiency)以及外部量子效率(Extemai Quantum Efficiency)有關。前者和氮化鎵系發光二極體主動層裡電子電 洞結合進而職$光子賴率有關。電子電崎容祕合，光子愈容 易產生’⑽量子效率就愈高，氮化鎵紐光二極體的發光效率通常 也就愈高。後者則和光子不錢化鎵紐光二極體本身的吸收與影 響、成功脫離氮化鎵系發光二極體的機率錢。愈多光子能釋放到氣 化鎵系發光二極體之外，外部量子效率就愈高，氮化鎵紐光二極體 的發光效率通常也就愈高。 氮化鎵系發光二極體的外部量子效率主要取決於其頂端表層的型態與 其折射率。習知的氮化鎵系發光二極體與空氣的折射率分別是2·5與 1。因為習知的氮化鎵祕光二極體的折射輪高，很容易形成内部^ 反射。所產生出來的光子，由於内部全反射的緣故，很不容易釋放到 1239665 · 氮化録系發光二極體之外。氮化鎵系發光二極體的外部量子效率因而 通常受到相當大的限制。 【發明内容】 本發明提出一種氮化鎵系發光二極體的結構，可以實際解決前 述相關技術中的限制及缺失。 本發明所提出的氮化鎵系發光二極體，其結構與習知的氮化鎵 系發光二極體最主要的差異是利用氮化矽（siN)、氮化矽與未 推雜的氮化銦鎵（InGaN)形成的短週期（Short Period)超晶格 (Superlattice)結構、或是氮化矽與未摻雜的氮化鋁銦鎵 (AlGalnN)形成的短週期超晶格結構三種做法之一，形成一位 於P型接觸層之上的薄層。在此薄層上，由於其氮化矽材質的 成長，使得氮化鎵系發光二極體的表面被微粗化。如此可以避 免氮化鎵系發光二極體較空氣為高的折射率導致内部全反 射，進而提升氮化鎵系發光二極體的外部量子效率以及發光效 率。 1 第一圖係習知的以及依據本發明的氮化鎵系發光二極體，在不 同的注入電流下的亮度數據圖。如第一圖所示，氮化鎵系發光 一極體具有前述由氮化矽與未摻雜的氮化銦鎵（InG2GaG8N)所 形成的短週期超晶格薄層，顯著地要比習知的氮化鎵系發光二 極體有更好的發光效率。 除了上述的優點，由於形成此一薄層的材料的低能隙特性，還 可以使得氮化鎵系發光二極體的金屬電極以及透明導電層和 薄層之間的電阻，要比習知氮化鎵系發光二極體的前二者和p 型接觸層之間的電阻更低，也因此更容易形成歐姆接觸。 1239665 兹配合下列圖示、實施例之詳細說明及申請專利範圍，將上述 及本發明之其他目的與優點詳述於後。 【實施方式】 第二圖係依據本發明之氮化鎵系發光二極體結構第一實施例 之示意圖。如第二圖所示，此實施例係以匕piane或R^iane 或A-Plane之氧化鋁單晶（Sapphire)或碳化矽(6H sic^4H_sic) 為基板10，其他可用於基板10的材質還包括Si、Zn〇、GaAs 或尖晶石（MgAlW4)，或是晶格常數接近於氮化物半導體之單 晶氧化物。然後在此基板1〇之一側面形成一由有一特定组成 的氮化銘鎵铜⑻aGabIni_a_bN，0Sa，b<1，所構成的緩衝層 20、以及在此緩衝層之上的一 n型接觸層3〇，此n型接觸層邓係 由氮化鎵(GaN)系材質構成。然後，在此η型接觸層3〇之上形成一主 動層40,此主動層40係由氮化銦鎵所構成、而且覆蓋部份11型接 觸層30的上表面。在η型接觸層30上表面未被主動層4〇覆蓋的部 份，另外形成有一負電極42。 此貫施例接著在主動層40上形成一 ρ型被覆層5〇。此ρ型被覆 層50係由氮化鎵系材質所構成。在此ρ型被覆層％之上，接 著是一材質為ρ型氮化鎵的ρ型接觸層60。在此ρ型接觸層6〇之上， 即為本發明重點之微粗化薄層7〇。在此實施例中，微粗化薄層7〇係由 氮化石夕（SidNe，〇<d，e<l)所構成，其厚度介於2人〜5〇人之間、成 長溫度介於600°C〜1100°C之間。 在微粗化薄層70上方，此實施例進一步分別形成互不重疊的一正電極 80與一透明導電層82。此正電極80可以是由Ni/Au合金、Ni/Pt 合金、Ni/Pd合金、Ni/Co合金、Pd/Au合金、Pt/Au合金、Ti/Au合金、 Cr/Au 合金、Sn/Au 合金、Ta/Au 合金、TiN、TiWNx(x20)、WSiy(y2〇) 等其中之一、或其他類似金屬材料所構成。此透明導電層82可以是 1239665 一金屬導電層或是一透明氧化層。此金屬導電層是由Ni/Au合金，Ni/Pt 合金，Ni/Pd合金，Pd/Αιι合金，Pt/Au合金，Cr/Au合金，Ni/Au/Be合金， Ni/Cr/Αιι合金，Ni/Pt/Αιι合金，Ni/Pd/Au合金及其它類似材料之一所構 成。此透明氧化層是由 ITO、CTO、ZnO:Al、ZnGa204、Sn〇2:Sb、 Ga203:Sn、AgIn02:Sn、In203:Zn、CuAI02、LaCuOS、NiO、CuGa02、 SrCu202其中之一所構成。 第三圖係依據本發明之氮化鎵系發光二極體結構第二實施例 之示意圖。如第三圖所示，此實施例和第一實施例有相同的結 構與成長方式。唯一的差別是在微粗化薄層所用的材質與結 構。在此實施例中，微粗化薄層72係由一氮化矽薄層721與一 氮化銦鎵薄層722交互重複堆疊所形成的短週期超晶格結 構。每一氮化矽薄層721，均係由具有其特定組成的氮化矽 (SifNgN，0<f，g<l)所構成，其厚度均介於2人〜2〇人之間、成長 溫度亦均介於600°C〜1100°C之間。不同的氮化矽薄層721的 氮化矽組成（即前述分子式的參數f，g)不一定相同。每一氮 化銦鎵薄層722，均係由未摻雜、具有其特定組成的氮化銦鎵 (IiihGauI^C^hSl)所構成，其厚度均介於2人〜2〇人之間、成長 溫度亦均介於之間。不同的氮㈣鎵薄層722 的I化銦鎵組成（即前述分子式的參心）不_定相同。 在此微粗化薄層72中，最底層（亦即直接位於口型接觸層之上: 石夕薄層721，其上再依次堆疊氮化_薄廣722、 =薄層721，依此類推。或者最底層也可以是氮化銦鎵薄 二再依次堆疊i化妙薄層721、氮化銦鎵薄層722, ^類，。氮化石夕薄層721錢化銦鎵薄層722依此方式交互 數=其重覆次數大於或等於二（亦即氮切薄層721的層 數f化銦鎵薄層722的層數均大於_ ^ ^ ^ 的總厚度不超過臂-)。雜化㈣ 1239665 第四圖係依據本發明之I化鎵系發光二極體結構第三實施例 之示意圖。如第四圖所示’此實施例和上述實施例有相同的社 構與成長方式。唯-的差科在微粗化薄層所用的材質與結 構。在此實施例中’微粗化薄層74係由一氮化石夕薄層％與一 氮化銘銦鎵錢742交互重複堆疊所形成的短週超晶格处 構。每-氮化㈣層7Μ ’均係由具有其特定組成的氮化石夕 (SiiNj^CXgd)所構成，其厚度均介於2人〜2〇Α之門成+田 度亦均介於6〇〇。(：〜ηοοχ之間。不同的氮化石夕“ 741的二 化矽組成（即前述分子式的參數i，]·)不一定相同。每一氮化鋁 銦鎵薄層742 ’均係由未摻雜、具有其特定組成的氮化紹姻嫁 O^lmln^Ga^nN’ 0<m’n<l，m+rK”所構成，其厚度均介於 2人〜2〇Α之間、成長溫度亦均介於6〇0〇c〜11〇〇。〔之間。不同 的氮化鋁銦鎵薄層742的氮化鋁銦鎵組成（即前述分;式的^ 數m，n )不一定相同。 在此微粗化薄層74中，最底層（亦即直接位於？型接觸層之上） 可以是氮化矽薄層741，其上再依次堆疊氮化鋁銦鎵薄層 742、氮化矽薄層741，依此類推。或者最底層也可以是氮/匕 銘銦鎵薄層742，其上再依次堆疊氮化石夕薄層741、氮化铭銦 鎵薄層742,依此類推。氮化矽薄層741與氮化鋁銦鎵薄層742 ，此方式交互重複堆疊，其重覆次數大於或等於二（亦即氮化矽 薄層741的層數與氮化鋁銦鎵薄層742的層數均大於或等於 二）。微粗化薄層74的總厚度不超過200入。 在别述的二個貫施例中，由於微粗化薄層中氮化矽材質的成長，使得 氮化鎵系發光二極體的表面被微粗化。如此可以避免氮化鎵系發光二 極體較空氣為高的折射率而導致内部全反射，進而提升氮化鎵系發光 二極體的外部量子效率以及發光效率。 1239665 以上所述者僅為用以解釋本發明 對本發明作任何形式上之限制，是广佳貫施例，並非企圖具以 下所作有關本發明之任何修錦或有在相同之發明精神 圖保護之範疇。 夂更音仍應包括在本發明意 【圖式簡單說明】 /1239665 IX. Description of the invention: [Technical field to which the invention belongs] The present invention relates to a gallium nitride based light emitting diode, and more particularly to a micro-roughened high-brightness gallium nitride based light emitting diode. Polar body structure. [Prior technology] Since gallium nitride (GaN) -based light-emitting diodes can be used to make light-emitting diodes of various colors by controlling the composition of materials, related technologies have become the focus of active research and development in the industry and academia in recent years. One of the research focuses of GaN-based light-emitting diodes in academia and industry is to understand the light-emitting characteristics of GaN-based light-emitting diodes, and then to propose ways to improve its light-emitting efficiency and brightness. Such high-efficiency and high-brightness GaN-based light-emitting diodes will be effectively used in the fields of outdoor display signage and automotive lighting in the future. The luminous efficiency of GaN-based light-emitting diodes is mainly related to the internal quantum efficiency (External Quantum Efficiency) and external quantum efficiency (Extemai Quantum Efficiency) of GaN-based light-emitting diodes. The former is related to the combination of the electron holes in the active layer of the GaN-based light-emitting diode, and is therefore related to the photon rate. The electrons are combined with each other, and the more easily photons are produced, the higher the quantum efficiency, and the higher the luminous efficiency of the gallium nitride light-emitting diode. The latter is related to the absorption and influence of the photon-free gallium photodiode itself, and the probability of successfully detaching from the gallium nitride-based light emitting diode. The more photons can be released out of the gallium-based light-emitting diode, the higher the external quantum efficiency, and the higher the light-emitting efficiency of the gallium nitride new-light diode. The external quantum efficiency of a gallium nitride-based light emitting diode depends mainly on the shape of its top surface layer and its refractive index. The refractive indices of the conventional gallium nitride-based light emitting diode and air are 2.5 and 1, respectively. Because the refraction wheel of the conventional gallium nitride secret light diode is high, it is easy to form internal reflection. The generated photons are not easily released outside the 1239665 · Nitride-based light-emitting diode due to total internal reflection. The external quantum efficiency of gallium nitride-based light-emitting diodes is therefore generally quite limited. [Summary of the Invention] The present invention provides a structure of a gallium nitride-based light emitting diode, which can actually solve the limitations and defects in the foregoing related technologies. The main difference between the structure of the GaN-based light-emitting diode proposed by the present invention and the conventional GaN-based light-emitting diode is the use of silicon nitride (siN), silicon nitride, and non-doped nitrogen. Three methods of short period superlattice structure formed by indium gallium (InGaN) or short period superlattice structure formed by silicon nitride and undoped aluminum indium gallium nitride (AlGalnN) One is to form a thin layer over the P-type contact layer. On this thin layer, due to the growth of its silicon nitride material, the surface of the gallium nitride-based light emitting diode is slightly roughened. In this way, it is possible to avoid the internal total reflection caused by the higher refractive index of the gallium nitride-based light-emitting diode than that of air, thereby improving the external quantum efficiency and light-emitting efficiency of the gallium-nitride-based light-emitting diode. 1 The first graph is a conventional brightness data graph of a gallium nitride based light emitting diode under different injection currents. As shown in the first figure, the gallium nitride-based light-emitting monolith has the aforementioned short-period superlattice thin layer formed of silicon nitride and undoped indium gallium nitride (InG2GaG8N), which is significantly better than conventional The GaN-based light-emitting diode has better luminous efficiency. In addition to the above advantages, due to the low energy gap characteristics of the material forming this thin layer, the resistance between the metal electrode of the gallium nitride-based light emitting diode and the transparent conductive layer and the thin layer can be made better than the conventional nitride The resistance between the first two gallium-based light emitting diodes and the p-type contact layer is lower, so it is easier to form an ohmic contact. 1239665 The above-mentioned and other objects and advantages of the present invention are described in detail below in conjunction with the following drawings, detailed description of the embodiments, and the scope of patent application. [Embodiment] The second diagram is a schematic diagram of the first embodiment of the gallium nitride-based light emitting diode structure according to the present invention. As shown in the second figure, in this embodiment, the substrate 10 is alumina single crystal (Sapphire) or silicon carbide (6H sic ^ 4H_sic) of Piane, R ^ iane, or A-Plane, and other materials that can be used for the substrate 10 It also includes Si, ZnO, GaAs or spinel (MgAlW4), or a single crystal oxide with a lattice constant close to that of a nitride semiconductor. Then on one side of the substrate 10, a buffer layer 20 composed of a gallium nitride gallium copper nitride aGabIni_a_bN, 0Sa, b < 1, and an n-type contact layer 3 on the buffer layer are formed. 〇 This n-type contact layer is made of a gallium nitride (GaN) -based material. Then, an active layer 40 is formed on the n-type contact layer 30. The active layer 40 is composed of indium gallium nitride and covers a part of the upper surface of the 11-type contact layer 30. A negative electrode 42 is additionally formed on a portion of the upper surface of the n-type contact layer 30 that is not covered by the active layer 40. This embodiment then forms a p-type coating layer 50 on the active layer 40. The p-type coating layer 50 is made of a gallium nitride-based material. Above this p-type coating layer%, a p-type contact layer 60 made of p-type gallium nitride is next. Above this p-type contact layer 60, the micro-roughened thin layer 70 which is the focus of the present invention. In this embodiment, the micro-roughened thin layer 70 is composed of nitride nitride (SidNe, 0 < d, e < l), and the thickness is between 2 and 50, and the growth temperature is between 600 ° C ~ 1100 ° C. Above the micro-roughened thin layer 70, this embodiment further forms a positive electrode 80 and a transparent conductive layer 82, which do not overlap each other. The positive electrode 80 may be made of Ni / Au alloy, Ni / Pt alloy, Ni / Pd alloy, Ni / Co alloy, Pd / Au alloy, Pt / Au alloy, Ti / Au alloy, Cr / Au alloy, Sn / Au Alloy, Ta / Au alloy, TiN, TiWNx (x20), WSiy (y2〇), or other similar metal materials. The transparent conductive layer 82 may be a 1239665 metal conductive layer or a transparent oxide layer. This metal conductive layer is made of Ni / Au alloy, Ni / Pt alloy, Ni / Pd alloy, Pd / Alt alloy, Pt / Au alloy, Cr / Au alloy, Ni / Au / Be alloy, Ni / Cr / Alt alloy, Ni / Pt / Alt alloy, Ni / Pd / Au alloy and other similar materials. The transparent oxide layer is made of one of ITO, CTO, ZnO: Al, ZnGa204, Sn02: Sb, Ga203: Sn, AgIn02: Sn, In203: Zn, CuAI02, LaCuOS, NiO, CuGa02, SrCu202. The third figure is a schematic diagram of the second embodiment of the gallium nitride-based light emitting diode structure according to the present invention. As shown in the third figure, this embodiment has the same structure and growth method as the first embodiment. The only difference is the material and structure used to micro-roughen the thin layer. In this embodiment, the micro-roughened thin layer 72 is a short-period superlattice structure formed by repeatedly stacking a silicon nitride thin layer 721 and an indium gallium nitride thin layer 722 alternately and repeatedly. Each of the silicon nitride thin layers 721 is composed of silicon nitride (SifNgN, 0 < f, g < l) with a specific composition, and the thickness is between 2 and 20, and the growth temperature They are also between 600 ° C ~ 1100 ° C. The silicon nitride composition (that is, the parameter f, g of the aforementioned molecular formula) of different silicon nitride thin layers 721 is not necessarily the same. Each of the indium gallium nitride thin layers 722 is composed of undoped indium gallium nitride (IiihGauI ^ C ^ hSl) with a specific composition, and the thickness is between 2 and 20 people, The growth temperature is also in between. The composition of indium gallium nitride (ie, the reference of the aforementioned molecular formula) of different thin gallium nitride gallium layers 722 may not be the same. In this micro-roughened thin layer 72, the bottom layer (that is, directly above the mouth-shaped contact layer: Shixi thin layer 721, which is sequentially stacked with nitride_thin 722, = thin layer 721, and so on. Or the bottom layer can also be a thin layer of indium gallium nitride, and then a thin layer 721, a thin layer of indium gallium nitride 722, etc. are sequentially stacked. Number of mode interactions = the number of times it is repeated is greater than or equal to two (that is, the number of layers of the nitrogen-cut thin layer 721 and the number of layers of the indium gallium thin layer 722 are greater than the total thickness of _ ^ ^ ^ does not exceed the arm-). Hybrid ㈣ 1239665 The fourth diagram is a schematic diagram of the third embodiment of the gallium-based luminescent diode structure according to the present invention. As shown in the fourth diagram, 'this embodiment has the same social structure and growth method as the above embodiment. -The material and structure of the poor section used in the micro-roughened thin layer. In this embodiment, the 'micro-roughened thin layer 74 is repeatedly stacked by a thin layer of nitride nitride and an indium gallium nitride 742. The formation of a short-period superlattice structure. Each 7M ′ of hafnium nitride layer is composed of a nitride nitride (SiiNj ^ CXgd) with a specific composition, and its thickness Between 2 people ~ 2〇Α 之 成 成 and degree are also between 600. (: ~ ηοοχ. Different nitride nitride Xi "741 silicon dioxide composition (that is, the parameter i of the aforementioned molecular formula,] ·) Is not necessarily the same. Each aluminum indium gallium nitride thin layer 742 ′ is composed of an undoped nitride with a specific composition O ^ lmln ^ Ga ^ nN '0 < m'n < l, m + rK ”, the thickness of which is between 2 people to 20 Å, and the growth temperature is also 6 000 c to 1 100. [between. Different aluminum indium gallium nitride thin layers The composition of the aluminum indium gallium nitride of 742 (that is, the above-mentioned number m, n) is not necessarily the same. In this micro-roughened thin layer 74, the bottom layer (that is, directly above the? -Type contact layer) may It is a silicon nitride thin layer 741, and an aluminum indium gallium nitride thin layer 742, a silicon nitride thin layer 741 are sequentially stacked thereon, and so on. Or the bottom layer may also be a nitrogen / indium gallium thin layer 742, which On top of this, the nitride nitride thin layer 741, the indium gallium nitride thin layer 742, and so on are sequentially stacked, and so on. The silicon nitride thin layer 741 and the aluminum indium gallium nitride thin layer 742 are stacked alternately in this manner, and the number of repetitions Greater than or equal to two That is, the number of layers of the silicon nitride thin layer 741 and the layer of the aluminum indium gallium nitride thin layer 742 are both greater than or equal to two.) The total thickness of the micro-roughened thin layer 74 does not exceed 200. In the other two In the embodiments, the growth of the silicon nitride material in the micro-roughened thin layer makes the surface of the GaN-based light-emitting diode slightly roughened. This can prevent the GaN-based light-emitting diode from being higher than the air. The internal refractive index caused by the internal refractive index increases the external quantum efficiency and luminous efficiency of the GaN-based light-emitting diode. 1239665 The above is only used to explain the present invention's restrictions on the form in any form. The good practice example is not intended to have any modification of the present invention or to protect the scope of the same invention spirit. Percussion should still be included in the meaning of the present invention.
附圖所顯示係提供作為具體呈現本說明書中所描述各組成元 件之具體化貫施例，並解釋本發明之主要目的以增進對本發明 之了解。 X 第一圖係習知的以及依據本發明的氮化鎵系發光二極體，在不同的注 入電流下的亮度數據圖。 第二圖係依據本發明之氮化鎵系發光二極體結構第一實施例 之示意圖。 第三圖係依據本發明之氮化鎵系發光二極體結構第二實施例 之示意圖。。 第四圖係依據本發明之氮化鎵系發光二極體結構第三實施例 之示意圖。 【主要元件符號說明】 10 基板 20 緩衝層 30 η型接觸層 40 主動層 42 負電極 50 ρ型被覆層 60 Ρ型接觸層 70 微粗化薄層 1239665 72 微粗化薄層 721 氮化矽薄層 722 氮化銦鎵薄層 74 微粗化薄層 741 氮化矽薄層 742 氮化鋁銦鎵薄層 80 正電極 82 透明導電層The accompanying drawings are provided as specific embodiments for specifically presenting the constituent elements described in this specification, and explain the main purpose of the present invention to improve the understanding of the present invention. The first graph of X is a brightness data graph of a conventional gallium nitride-based light emitting diode according to the present invention under different injection currents. The second figure is a schematic diagram of the first embodiment of the gallium nitride-based light emitting diode structure according to the present invention. The third figure is a schematic diagram of the second embodiment of the gallium nitride-based light emitting diode structure according to the present invention. . The fourth figure is a schematic diagram of the third embodiment of the gallium nitride-based light emitting diode structure according to the present invention. [Description of main component symbols] 10 Substrate 20 Buffer layer 30 η-type contact layer 40 Active layer 42 Negative electrode 50 ρ-type coating layer 60 P-type contact layer 70 Micro-roughened thin layer 1239665 72 Micro-roughened thin layer 721 Silicon nitride thin Layer 722 Indium gallium nitride thin layer 74 Microroughened thin layer 741 Silicon nitride thin layer 742 Aluminum indium gallium nitride thin layer 80 Positive electrode 82 Transparent conductive layer