201039458 六、發明說明： 【發明所屬之技術領威】 本發明係關於〆罐紫外光偵測器’尤指利用一圓形電 極單元與一環形電極單元之紫外光彳貞測器。 【先前技術】 研究報告指出，過度曝曬會造成身體細胞病變’其主 要原因是由於太陽光中之紫外光（ultraviolet, UV)具有強 〇 烈的細胞損壞能力。紫外光係為一種短波輻射光，依據其 波長可區分為三大類，其中包含UVA(400 nm至320 nm)、 UVB ( 320 nm 至 28〇 ηιη)以及 UVC ( 280 nm 至 100 nm)， 隨著波長下降其光照能量亦隨之上升。 一般來說，太陽光輻射至地球表面大多以UVA以及 UVB為主’其中前者會造成皮膚表面膠原蛋白裂解導致自 由基增生而產生老化的現象，後者則會造成基因病變而導 致癌細胞的增生。有幸於臭氧層（Ozone Layer，03 )的保 護’大部份的uvc在通過大氣層時就被吸收；藉此，生物 可免於受到短波長輻射的危害。 然’氟氣石炭化物（Chlorofluorocarbons，CFCs)的大 量使用’已經造成南極上空之臭氧層出現與北美洲相當大 小之破洞’這使得大量的UVC輻射至地表’導致皮膚癌的 罹患率急遽上升。因此，當務之急是開發能夠有效偵測UVC 之紫外光偵測器，以警告當UVC過量時避免到戶外活動。 除此之外，上述之紫外光偵測器更可應用於環境、工業、 3 201039458 太空以f科學等領域中，藉以發揮其最大經濟效益。201039458 VI. Description of the Invention: [Technology Leading Invention] The present invention relates to a canister ultraviolet light detector, particularly an ultraviolet light detector using a circular electrode unit and a ring electrode unit. [Prior Art] The research report pointed out that excessive exposure causes body cell pathology. The main reason is that ultraviolet light (UV) in the sun has strong cell damage. Ultraviolet light is a kind of short-wave radiation, which can be divided into three categories according to its wavelength, including UVA (400 nm to 320 nm), UVB (320 nm to 28 〇ηηη), and UVC (280 nm to 100 nm). As the wavelength decreases, its illumination energy also increases. In general, most of the sun's radiation to the surface of the earth is dominated by UVA and UVB, where the former causes collagen cleavage on the skin surface to cause aging of the free radicals, which in turn causes genetic disease and leads to the proliferation of cancer cells. Fortunately for the protection of the ozone layer (Ozone Layer, 03), most of the uvc is absorbed as it passes through the atmosphere; thereby, organisms are protected from short-wavelength radiation. However, the large use of 'Chlorofluorocarbons (CFCs) has caused the ozone layer over the Antarctic to appear quite small and small in North America'. This has caused a large amount of UVC radiation to the surface, causing an acute increase in the incidence of skin cancer. Therefore, it is imperative to develop an ultraviolet light detector that can effectively detect UVC to warn against outdoor activities when the UVC is excessive. In addition, the above-mentioned ultraviolet light detector can be applied to the environment, industry, 3 201039458 space to f science and other fields, in order to maximize its economic benefits.
G Ο 目刚系見之紫外光偵測器，主要有光倍增管（pMT)、 石夕^一極體以及半導體紫外光制器。上述前兩者已商業 化量產’光電倍增管具有高增益、低誠之優點，然而卻 有車乂易碎、體積大及耗電大之缺點。而砍二極體雖然體積 】耗電低，因使用之石夕材料易受環境影響元件特性，且 :能隙小而無法對不同的紫外光作選擇性偵測，需加裝滤 一片（filter) ’以致降低其量子效率咖她射胸㈣力。 龜^強上4兩種紫外光仙]器之不目前產業界正 料導體紫外光偵㈣。基於半導體材料具有高熱 =^ =電常數、高熱傳導度、高崩潰電壓以及寬直 .^. 匕們被廣泛應用於高功率、短波長 “70件且被視為射_性之先進材料。 請參閱第一圖，係為習知主 立體示意圖。該紫外以_ 1=_]器1&之 (MSM)結構，該紫外光债測 ;^金屬_+導體-金屬 _、一吸光層雇、與-指又型=而上依序疊置一基板 係用以吸收紫外光，並產生電流於f "。該吸光層篇 測量該指叉型電極3_之電济信，又型電極施。藉由 但上述金屬-半導體金屬結構紫P可推估紫外光之照度。 度與響應綱、製㈣單=光_ la雖然靈敏 又型電極施内的^排缺陷密度 、 得元件的不穩定度增加，另外 W漏電流’使 壓較古，曰又型電極3〇〇a之觸及電 車又问®此亦會產生較高之暗電流與較高之功耗。 4 201039458 【發明内容】G Ο 刚 系 紫外 紫外 紫外 紫外 紫外 紫外 紫外 紫外 紫外 紫外 紫外 紫外 紫外 紫外 紫外 紫外 紫外 紫外 紫外 紫外 紫外 紫外 紫外 紫外 紫外 紫外 紫外 紫外 紫外 紫外 紫外 紫外 紫外 紫外The above two have been commercialized in mass production. The photomultiplier tube has the advantages of high gain and low sincerity, but it has the disadvantages of being fragile, bulky and power consuming. Although the size of the cut diode is low, the use of the stone material is susceptible to the characteristics of the environment, and the energy gap is small and it is impossible to selectively detect different ultraviolet light. ) 'Thus, to reduce its quantum efficiency, she shot the chest (four) force. Turtle ^ strong on the two kinds of ultraviolet light sensation] is not currently the industry is expected to conduct ultraviolet light detection (four). Based on semiconductor materials with high heat = ^ = electrical constant, high thermal conductivity, high breakdown voltage and wide straight. ^. We are widely used in high-power, short-wavelength "70 pieces and is considered as an advanced material for radiation. Please Referring to the first figure, it is a schematic diagram of a conventional main stereo. The ultraviolet is _ 1 = _] 1 & (MSM) structure, the ultraviolet light debt measurement; ^ metal _ + conductor - metal _, a light absorbing layer hire, A substrate is sequentially stacked on the surface of the finger to absorb ultraviolet light, and an electric current is generated in f ". The light absorption layer measures the electric signal of the finger-shaped electrode 3_, and the electrode is applied However, the above-mentioned metal-semiconductor metal structure violet P can be used to estimate the illuminance of ultraviolet light. Degree and response, system (4) single = light _ la although sensitive and type electrode electrode defect density, component instability The degree is increased, and the W leakage current makes the pressure more ancient, and the touch of the electrode of the 曰-type electrode 3〇〇a also causes a higher dark current and higher power consumption. 4 201039458 [Summary of the Invention]
綜上所述，為了克服習知半導體紫外光偵測器，具有較 面漏電流與暗電流之缺點。本發明之目的，係在提供—種紫 外光偵測器，其利用一圓形電極與一環形電極單元設置於一 氮化鋁吸光層上，可降低暗電流，並藉由氮化鋁沉積於氮化 鎵層上，可大幅地減少其差排缺陷密度，因此可以降低漏電 流。由於漏電流與暗電流變小，進而使紫外光偵測器產生的 訊號更為清晰和更有效地接收微弱的訊號。 為了達成上述之目的，本發明係提供一種紫外光偵測 盗，係包含：一基板、一氮化鋁吸光層與一電極層。該基 板係包含一藍寶石層與一疊置於該藍寶石層上之氮化鎵 層。該氮化鋁吸光層係設置於該氮化鎵層上，該氮化鋁吸 光層係於紫外絲射後產m収該€極層係設置 於該氮化鋁吸光層上，並用以接收該電流。 。該電極層係包含一圓形電極單元與一環形電極單元。 ，圓幵/电極單元m置於·圓形電極單元之外圍，並與該 圓形電極單元間距離一間隙。 /、β 大所迷，本發明係藉由1"化紹沉積於氮化鎵層上，可 其内高差排缺陷密度’因此可以降低漏電流，並 利用一_電極與-環形電極單元，以經 積效應下得到較低的觸及電壓，進恤：電 外光偵測器具有較高之暗電流之缺=改㈡知之半導體紫 5 201039458 關於本發明之優點與精神可以藉由以下的發明詳述及 所附圖式得到進一步的暸解。 【實施方式】 請參閱第二圖，係本發明之紫外光偵測器1之立體示意 圖。該紫外光偵測器1係包含一基板100、一氮化铭吸光声 200、與一電極層300。 該基板100係包含一藍寶石（Sapphire)層ι1〇與一氣化 Ο 鎵（GaN)層120。該藍寶石層11〇係由藍寶石所構成，其 厚度係可為lOOum至500um ’於本實施例中係為33〇um。於 另一實施例中’可不包含該藍寶石層110或是該氮化鎵層 120 ° 該氮化鎵層120係由氮化鎵所構成，其可利用有機金屬 化學氣相沉積法（MOC VD)成長氮化鎵於藍寶石基板1〇〇 上。該氮化蘇層120之厚度係可為1 um至1 〇um，於本實施例 中係為3.6um。其中該有機金屬化學氣相沉積法係為一習知 ® 技術，在此不加累述。 該氮化鎵層120係可進一步分為一未摻雜（und〇ped)氮 化鎵層121與一 p-type氮化鎵層122。該未摻雜氮化鎵層pi 之厚度係可為0.5um至5um，於本實施例中係為l 8um。該 P-type氮化鎵層122之厚度係可為〇.5um至5um，於本實施 例中係為1.8um。於另一實施例中，可不包含該p_type氮化 鎵層122或是該未摻雜氮化鎵層121，該未摻雜氮化鎵層ι21 亦可設置於該P-type氮化鎵層122之上方。 6 201039458 該氮化鋁（AIN)吸光層200係由氮化鋁所構成，該氮 化鋁吸光層200係於紫外光照射後產生一電流。該氮化鋁吸光層 200具高熱穩定性、高介電常數、高導熱度、寬直接能隙 (6. 2eV〜3. 4eV)使得對可見光不敏感，並且可以承受很大的 電場而不崩潰，尤其是氮化鋁能隙所對應到的波長為2〇〇nm 左右，所以非常適合用於製作紫外光感測器的材料。 該氮化銘吸光層200可以迴旋賤鑛之方式沉積設置於該 ❹In summary, in order to overcome the conventional semiconductor ultraviolet light detector, it has the disadvantages of surface leakage current and dark current. The object of the present invention is to provide an ultraviolet light detector which is disposed on an aluminum nitride light absorbing layer by using a circular electrode and a ring electrode unit to reduce dark current and is deposited by aluminum nitride. On the gallium nitride layer, the difference in the defect density can be greatly reduced, so that the leakage current can be reduced. Since the leakage current and the dark current become smaller, the signal generated by the ultraviolet detector is more clear and more efficient to receive weak signals. In order to achieve the above object, the present invention provides an ultraviolet light detecting and stealing system comprising: a substrate, an aluminum nitride light absorbing layer and an electrode layer. The substrate comprises a sapphire layer and a gallium nitride layer stacked on the sapphire layer. The aluminum nitride light absorbing layer is disposed on the gallium nitride layer, and the aluminum nitride light absorbing layer is formed on the ultraviolet light ray, and the aluminum layer is disposed on the aluminum nitride light absorbing layer, and is configured to receive the aluminum nitride light absorbing layer Current. . The electrode layer comprises a circular electrode unit and a ring electrode unit. The round 幵/electrode unit m is placed on the periphery of the circular electrode unit and has a gap from the circular electrode unit. The invention is based on 1" The lower touch voltage is obtained by the product effect, and the electronic light detector has a high dark current. = (2) Known semiconductor violet 5 201039458 The advantages and spirit of the present invention can be achieved by the following invention The details and the drawings are further understood. [Embodiment] Please refer to the second drawing, which is a perspective view of the ultraviolet light detector 1 of the present invention. The ultraviolet light detector 1 includes a substrate 100, a nitrided light absorbing sound 200, and an electrode layer 300. The substrate 100 comprises a sapphire layer ι1 〇 and a vaporized gallium GaN (GaN) layer 120. The sapphire layer 11 is composed of sapphire and may have a thickness of from 100 μm to 500 μm in the present embodiment of 33 μm. In another embodiment, the sapphire layer 110 or the gallium nitride layer 120 may be included. The gallium nitride layer 120 is composed of gallium nitride, which can utilize organometallic chemical vapor deposition (MOC VD). Grow GaN on the sapphire substrate. The thickness of the nitridation layer 120 may be 1 um to 1 〇 um, which is 3.6 um in this embodiment. The organometallic chemical vapor deposition method is a conventional ® technology and will not be described here. The gallium nitride layer 120 can be further divided into an undoped gallium nitride layer 121 and a p-type gallium nitride layer 122. The undoped gallium nitride layer pi may have a thickness of 0.5 um to 5 um, which is l 8 um in this embodiment. The P-type gallium nitride layer 122 may have a thickness of um5 um to 5 um, which is 1.8 um in this embodiment. In another embodiment, the p-type gallium nitride layer 122 or the undoped gallium nitride layer 121 may not be included, and the undoped gallium nitride layer ι21 may also be disposed on the P-type gallium nitride layer 122. Above. 6 201039458 The aluminum nitride (AIN) light absorbing layer 200 is composed of aluminum nitride, and the aluminum nitride light absorbing layer 200 generates a current after ultraviolet light irradiation. The aluminum nitride light absorbing layer 200 has high thermal stability, high dielectric constant, high thermal conductivity, wide direct energy gap (6.2 eV~3. 4 eV), makes it insensitive to visible light, and can withstand a large electric field without collapse In particular, the aluminum nitride energy gap corresponds to a wavelength of about 2 〇〇 nm, so it is very suitable for the material used to make the ultraviolet light sensor. The nitriding light absorbing layer 200 may be deposited on the crucible in a manner of gyrating ore
P-type氮化鎵層122，其沉積時之溫度可以為3〇〇度。該氮 化銘吸光層200之厚度係可為〇,ium至5um之間，於本實施 例中係為lum。由於氮化鋁與氮化鎵間晶格不匹配 mismatch)較小（〜2.4%) ’可比直接在藍寶石基板1〇〇上長氮 化銘可大巾*地減少其差排缺陷密度，@此可以降低暗電流。 所謂的暗電流係就是在未照㈣由蕭特基接觸的電流機制造 成的電流.。當光照射到半導體上時，使得半導體因為光激發 產生電子電洞對，造成與暗電流相比所產生額外的電流，稱 為光電流。 迴旋雜方法的優點是將電漿經由R.F·如的誘發揭 :後，形成-個強烈的磁場，此迴旋波的相速度沿著磁場方 :由】擴散腔體傳遞’而電場將加速離子朝基板⑽運 藉提供㈣能高密㈣電漿，使得轉可在1G-4T〇rr 古生’較一般單純之磁控濺鑛系統低約2個。rder，如此f 2:=粒子之平均自由路徑可增加至30，-，造成類 ⑽夕>改善薄膜表面平整度及結晶特性。由於該迴旋 X工、係為-習知之技術，更細部之特徵在此不多加累 7 201039458 述。 於另一實施例中，若無該氮化鎵層120則可直接設置於 該藍寶石層110上，若無該P-type氮化鎵層122或是該未摻 雜氮化鎵層121設置於該P-type氮化鎵層122之上方則可直 接設置於該未摻雜氮化鎵上。 該電極層300係設置於該氮化鋁吸光層200上，並用以 接收該電流。該電極層300亦可以迴旋濺鍍之方法沈積設置 於该氮化銘吸光層200上’並經由微影触刻方法於該電極層 ° 300上形成該圓形電極單元310與該環形電極單元32〇。該電 極層300係可由鋁金屬所構成。該電極層300之厚度係可為 5〇〇埃至4000埃，於本實施例中係為25〇〇埃。上述之該微 景》链刻方法係為一習知技術，在此並多加敘述。 另晴一併參閱第三圖，該圓形電極單元31 〇係設有一圓 心C1，該圓形電極單元310之外緣至該圓心01係設有一第 一半徑R1 ’該圓形電極單元310具有—第一面積入丨。該第 〇 一半徑R1係可為5011„1至200腿，於本實施例中係為112⑽。 該環形電極單元320與該圓形電極單元31〇同圓心C1， 該環形電極單元320之外緣至該圓心C1係設有—第二半徑 該環形電極單元320係以該圓心C1為中心環繞於_ 形電極單元310之外圍，ϋ與該圓形電極單元31〇間距離一 間隙m。該第二半徑R2係可為210um至麵⑽，或是別⑽ 以亡，於本實施例係可為640um。該環形電極單元32〇設有 一第二面積A2。 於本發明中該圓形電極單元M0與該環形電極單元32〇 8 201039458 具有非對稱面積比，該第二面積A2係較該第〜 20倍，於本實施例中係大於4〇倍。該間隙d ^ A大於 2um至3〇um，於本實施例中係為12um。之範圍係可為 於另一實施例中，該環形電極單元32〇 並相互間隔__段距離，以增加本發明之效能柯為複數個， 利用本發明之紫外光備測器i作為紫^ 外光照射至氮化铭吸光層200,並利 j日夺係㈣ 至價帶，並產生電子—電洞對。該電子從導帶激發 〇文到電場作用分離並穿越半導體分別往該圓开:：f吸收區内 α〇 形電極單元310 二=電極早元320。測量移動置該圓形電極單元斑 "衣形電極單元32〇之電流可間接得知紫外光之昭射量。 之4=第四圖與第五圖，係為本發明之紫外光偵測器1 燈(貝〇_圖。於本發明之中使用之光源為功率1卿的仇 偏;^ π UmlamP) ’波段辜巳圍為2〇〇nm〜4〇〇nm間，並量測 氮屏〜脚照光後的光電流。由於本發明之氮化紹沉積於 ❹310|_曰$120上，並具有非對稱面積比之一圓形電極單元 於第二罔％形電極單70 320，因在匕具有良好之光電流特性，另 可知其測得之暗電流亦十分小。 +驟m圖’係本發明紫外絲測器1之製作方法的 二：。利用，機金屬化學氣相沉積法(m〇cvd)成長氮化鎵 ，於。監寶石層110上（步驟S101)。 7用迴旋濺鍍法於該氮化鎵層120上沉積一氮化 層 200 (步驟 S103)。 利用迴旋賤錢法於氮化鋁吸光層200上沉積一電極層 9 .201039458 300 (步驟 S105)。 利用微影蝕刻方法於該電極層300上形成一圓形電極單 元310與一環形電極單元320 (步驟S107)。 綜上所述，本發明係藉由氮化鋁沉積於氮化鎵層上，可 大幅地減少其内高差排缺陷密度，因此可以降低漏電流，並 利用具有非對稱面積比之圓形電極單元與環形電極單元，得 到較低的觸及電壓，進而降低暗電流、提高光電流以及降低 功率的消耗。因此本發明能改善習知之半導體紫外光偵測器 Ο 具有較高之暗電流之缺失。 藉由以上較佳具體實施例之詳述，係希望能更加清楚 描述本發明之特徵與精神，而並非以上述所揭露的較佳具 體實施例來對本發明之範疇加以限制。相反地，其目的是 希望能涵蓋各種改變及具相等性的安排於本發明所欲申請 之專利範圍的範疇内。 【圖式簡單說明】 ° 第一圖，係為習知之半導體紫外光偵測器之立體示意圖； 第二圖，係本發明之紫外光偵測器之立體示意圖； 第三圖，係本發明之紫外光偵測器之俯視示意圖； 第四圖與第五圖，係為本發明之紫外光偵測器之實驗數據 圖；以及 第六圖，係本發明紫外光偵測器之製作方法的步驟圖。 【主要元件符號說明】 10 .201039458 [習知技術] 紫外光偵測器la 基板100a 吸光層200a 指叉型電極300a [本發明] 紫外光偵測器1 基板100 ® 藍寶石層110 氮化鎵層120 未摻雜氮化鎵層121 P-type氮化鎵層122 氮化鋁吸光層200 電極層300 圓形電極單元310 環形電極單元320 〇 第一面積A1 第二面積A2 圓心C1 第一半徑R1 第二半徑R2 間隙D1 πThe P-type gallium nitride layer 122 can be deposited at a temperature of 3 degrees. The thickness of the nitrogen-based light absorbing layer 200 may be between ium and ium to 5 μm, which is lum in this embodiment. Due to the lattice mismatch between aluminum nitride and gallium nitride mismatch) is small (~2.4%) 'Comparable directly on the sapphire substrate 1 长 氮化 铭 可 大 大 * 地 地 地 地 地 减少 减少 减少 减少 减少 减少 减少 减少 , , , , , @ It can reduce dark current. The so-called dark current system is the current produced by a current machine that is not exposed to (4) by Schottky. When light strikes the semiconductor, the semiconductor is caused to generate an electron hole pair due to photoexcitation, causing an additional current generated compared to the dark current, referred to as photocurrent. The advantage of the cyclotron method is that the plasma is induced by RF. After the formation, a strong magnetic field is formed. The phase velocity of the cyclotron wave is along the magnetic field side: the diffusion cavity is transmitted by the electric field. The substrate (10) provides (4) capable of high-density (four) plasma, so that the transfer can be about 2 in the 1G-4T〇rr Gusheng's, compared with the general simple magnetron splashing system. Rder, such that the average free path of the particles can be increased to 30, -, causing the class (10) to improve the film surface flatness and crystallization characteristics. Due to the technique of the gyro X-ray, which is a well-known technique, the features of the more detailed parts are not included here. In another embodiment, the gallium nitride layer 120 can be directly disposed on the sapphire layer 110. If the P-type gallium nitride layer 122 or the undoped gallium nitride layer 121 is not disposed, The P-type gallium nitride layer 122 can be directly disposed on the undoped gallium nitride. The electrode layer 300 is disposed on the aluminum nitride light absorbing layer 200 and is configured to receive the current. The electrode layer 300 can also be deposited on the nitriding light absorbing layer 200 by a method of gyro-sputtering and forming the circular electrode unit 310 and the ring electrode unit 32 on the electrode layer 300 via a lithography process. Hey. The electrode layer 300 can be composed of aluminum metal. The electrode layer 300 may have a thickness of 5 angstroms to 4,000 angstroms, and is 25 angstroms in this embodiment. The above-mentioned "micro-view" chain engraving method is a conventional technique and will be described herein. Referring to the third figure, the circular electrode unit 31 is provided with a center C1, and the outer edge of the circular electrode unit 310 is provided with a first radius R1 from the outer core 01. The circular electrode unit 310 has - The first area is in. The first radius R1 can be 5011 „1 to 200 legs, which is 112 (10) in this embodiment. The ring electrode unit 320 is identical to the circular electrode unit 31 by a center C1, and the outer edge of the ring electrode unit 320 The center C1 is provided with a second radius. The ring electrode unit 320 surrounds the periphery of the _-shaped electrode unit 310 around the center C1, and a distance m between the 圆形 and the circular electrode unit 31. The second radius R2 can be 210 um to face (10), or else (10) to die, which can be 640 um in this embodiment. The ring electrode unit 32 is provided with a second area A2. In the present invention, the circular electrode unit M0 The annular electrode unit 32〇8 201039458 has an asymmetric area ratio, and the second area A2 is ～20 times larger than the first, and is more than 4 times in the embodiment. The gap d ^ A is greater than 2um to 3〇um. In the present embodiment, the range is 12 um. The range may be in another embodiment, the ring electrode unit 32 is spaced apart from each other by a distance of __ to increase the performance of the present invention, and the present invention is utilized. The ultraviolet light detector i is irradiated to the nitriding light absorbing layer 2 as a purple light 00, and the J-day (4) to the valence band, and the generation of electron-hole pairs. The electrons are separated from the conduction band to the electric field and pass through the semiconductor to the circle::f absorption area The electrode unit 310==electrode early 320. Measuring the current of the circular electrode unit spot" the shape of the electrode unit 32〇 can indirectly know the amount of ultraviolet light. 4=fourth and fifth pictures It is the ultraviolet light detector 1 lamp of the present invention (Beiyu_Fig. The light source used in the present invention is the power of 1 Qing's hatred; ^ π UmlamP) 'the band circumference is 2 〇〇 nm~ Between 4 〇〇 nm, and measure the photocurrent after the nitrogen screen ~ foot illumination. Since the nitriding of the present invention is deposited on ❹310|_曰$120, and has an asymmetric area ratio of one of the circular electrode units in the second罔%-shaped electrode single 70 320, because of the good photocurrent characteristics in 匕, it is also known that the measured dark current is also very small. + m m diagram ' is the second method of the production method of the ultraviolet ray detector 1 of the present invention. The gallium nitride is grown by a metal chemical vapor deposition method (m〇cvd) on the gemstone layer 110 (step S101). A nitride layer 200 is deposited on the gallium nitride layer 120 by a cyclotron sputtering process (step S103). An electrode layer 9 .201039458 300 is deposited on the aluminum nitride light absorbing layer 200 by a spin-drying method (step S105). The lithography method forms a circular electrode unit 310 and a ring electrode unit 320 on the electrode layer 300 (step S107). In summary, the present invention is deposited on the gallium nitride layer by aluminum nitride. Significantly reduce the density of the internal high-difference defect, so that the leakage current can be reduced, and the circular electrode unit and the ring electrode unit having an asymmetric area ratio can be used to obtain a lower contact voltage, thereby reducing dark current, increasing photocurrent, and Reduce power consumption. Therefore, the present invention can improve the conventional semiconductor ultraviolet light detector Ο having a high dark current loss. The features and spirit of the present invention are intended to be more apparent from the detailed description of the preferred embodiments. On the contrary, the intention is to cover various modifications and equivalents within the scope of the invention as claimed. BRIEF DESCRIPTION OF THE DRAWINGS The first figure is a schematic view of a conventional semiconductor ultraviolet detector; the second figure is a schematic view of the ultraviolet light detector of the present invention; A schematic view of the ultraviolet light detector; the fourth and fifth figures are experimental data diagrams of the ultraviolet light detector of the present invention; and the sixth figure is a step of the method for fabricating the ultraviolet light detector of the present invention. Figure. [Main component symbol description] 10.201039458 [Prior Art] Ultraviolet light detector la substrate 100a Light absorbing layer 200a Finger-shaped electrode 300a [Invention] Ultraviolet light detector 1 Substrate 100 ® Sapphire layer 110 Gallium nitride layer 120 undoped gallium nitride layer 121 P-type gallium nitride layer 122 aluminum nitride light absorbing layer 200 electrode layer 300 circular electrode unit 310 ring electrode unit 320 〇 first area A1 second area A2 center C1 first radius R1 Second radius R2 gap D1 π