200416831 Ο) 玖、發明說明 【發明所屬之技術領域】 本發明係關於具備由III族氮化物半導體層和定向性 優異的磷化硼層所構成的異質接面構造的磷化硼系化合物 半導體兀件、及其製造方法、以及發光二極體。 【先前技術】 習知上，氮化鋁·鎵.銦（AlxGaYInzN:〇SX、Y、Z ‘ 1，X + Y + Z=l )等之III族氮化物半導體被利用爲發光 二極體（LED)的發光層或者包覆（ciac[)層，或者高移 動度場效型電晶體（TEGFET)的電子通道（channel)層 或者電子供給層等（專利文獻1、非專利文獻1等）。 利用ΠI族氮化物半導體之元件（π I族氮化物半導體 元件）爲了使其發揮元件機能，一般爲具備III族氮化物 半導體層相互之異質接面構造。例如，在專利文獻1中， 揭示了藉由氮化鎵（GaN)和氮化鎵·銦（GaYInzN:0SY 、ZS1 ’ Y + Z= l)之異質接面，以構成LED或者雷射二 極體（LD )的發光部的例子。 構成化合物半導體元件之111族氮化物半導體層或者 111族氮化物半導體層所形成的異質接面構造，習知上主 要係藉由氣相成長法而生成於藍寶石（α — Al2〇3單結晶 )基板上（專利文獻2等）。 但是，例如藍寶石基板和氮化鎵（GaN )的晶格失配 (mismatch)約大至16% (非專利文獻2等），知道在形 -4- (2) (2)200416831 成於藍寶石基板上的氮化鎵層含有超過1 xl 08/cm2的多 量錯合（misfit )錯位（非專利文獻3等）。在由氮化鎵 等之III族氮化物半導體所形成的異質接面中，錯合錯位 超過異質接面部而傳播於上層◦因此，在習知技術中，難 於穩定獲得錯位密度低的異質接面構造。 另一方面，本發明人發現磷化硼（B P )可有效阻止 來自III族氮化物半導體層的錯合錯位之傳播。 在專利文獻2〜7等中，揭示：在由六方晶格纖維鋅 礦型（Wurtzite )的氮化鎵等所形成的III族氮化物半導 體層上接合形成憐化硼層’以構成發光兀件之技術。但是 ，在習知技術中，並非意圖阻止來自III族氮化物半導體 層之錯合錯位的傳播（參考專利文獻8、9 )，具備可充 分而穩定地阻止來自III族氮化物半導體層之錯合錯位的 傳播之有效的磷化硼層的結晶組織構造還未爲所知。因此 ，習知上，很難穩定地獲得洩漏電流少，可發揮良好整流 特性之III族氮化物半導體層和磷化硼層的pn接面構造 〔專利文獻1〕 日本專利特公昭5 5 - 3 8 3 4號公報 〔專利文獻2〕 日本專利特開平1 0-2425 1 4號公報 〔專利文獻3〕 曰本專利特開平1 0-2425 1 5號公報 〔專利文獻4〕 -5- (3) (3)200416831 日本專利特開平1 0-242567號公報 〔專利文獻5〕 日本專利特開平1 0 - 2 4 2 5 6 8號公報 〔專利文獻6〕 日本專利特開平1 0-242569號公報 〔專利文獻7〕 日本專利特開平1 0-247745號公報 〔專利文獻8〕 曰本專利特開平1 0-247760號公報 〔專利文獻9〕 日本專利特開平1 0-24776 1號公報 〔非專利文獻1〕 赤崎 勇編著，「ΙΠ族氮化物半導體（Advanced Electronics 1-21)」，初版，（株）培風館，1 999 年 12 月 8 日，p.285-293 〔非專利文獻2〕200416831 〇). Description of the invention [Technical field to which the invention belongs] The present invention relates to a boron phosphide-based compound semiconductor having a heterojunction structure composed of a group III nitride semiconductor layer and a boron phosphide layer having excellent directivity. Piece, its manufacturing method, and light emitting diode. [Prior art] Conventionally, group III nitride semiconductors such as aluminum nitride, gallium, indium (AlxGaYInzN: 0SX, Y, Z'1, X + Y + Z = 1) are used as light emitting diodes ( LED), a light-emitting layer, or a ciac [) layer, or an electron channel layer or an electron supply layer of a high-mobility field-effect transistor (TEGFET) (Patent Document 1, Non-Patent Document 1, etc.). A device using a group I nitride semiconductor (a group I nitride semiconductor device) generally has a heterojunction structure with a group III nitride semiconductor layer in order to make the device function. For example, in Patent Document 1, it is disclosed that a LED or a laser diode is constituted by a heterojunction of gallium nitride (GaN) and gallium nitride · indium (GaYInzN: 0SY, ZS1 'Y + Z = 1). An example of a light emitting portion of a body (LD). The heterojunction structure formed by the Group 111 nitride semiconductor layer or the Group 111 nitride semiconductor layer constituting a compound semiconductor device is conventionally mainly generated in sapphire (α-Al2 03 single crystal) by a vapor phase growth method. On a substrate (Patent Document 2 and the like). However, for example, a lattice mismatch between a sapphire substrate and gallium nitride (GaN) is about 16% (Non-Patent Document 2 and the like), and it is known that the sapphire substrate is formed on a sapphire substrate in the shape of -4- (2) (2) 200416831. The upper gallium nitride layer contains a large amount of misfit misalignment exceeding 1 × 10 08 / cm 2 (Non-Patent Document 3 and the like). In a heterojunction formed by a group III nitride semiconductor such as gallium nitride, the dislocation dislocation exceeds the heterojunction and propagates to the upper layer. Therefore, it is difficult to obtain a heterojunction with a low dislocation density in the conventional technique. structure. On the other hand, the present inventors have found that boron phosphide (B P) can effectively prevent the propagation of dislocations and dislocations from the group III nitride semiconductor layer. Patent Documents 2 to 7 and the like disclose that a group III nitride semiconductor layer formed of a hexagonal lattice fiber zincite type (Wurtzite) gallium nitride or the like is bonded to form a boron-reduced layer to form a light-emitting element. Technology. However, in the conventional technology, it is not intended to prevent propagation of misalignment and misalignment from a group III nitride semiconductor layer (refer to Patent Documents 8 and 9), and it is possible to sufficiently and stably prevent misalignment from a group III nitride semiconductor layer. The crystal structure of the boron phosphide layer effective for dislocation propagation is unknown. Therefore, it is conventionally difficult to stably obtain a pn junction structure of a group III nitride semiconductor layer and a boron phosphide layer with a small leakage current and good rectification characteristics. [Patent Document 1] Japanese Patent Publication No. 5-5-3 8 3 No. 4 [Patent Document 2] Japanese Patent Laid-open No. 1 0-2425 1 No. 4 [Patent Document 3] Japanese Patent Laid-open No. 1 0-2425 1 No. 5 [Patent Document 4] -5- (3 (3) 200416831 Japanese Patent Laid-Open No. 1 0-242567 [Patent Document 5] Japanese Patent Laid-Open No. 1 0-2 4 2 5 6 8 [Patent Document 6] Japanese Patent Laid-Open No. 1 0-242569 [Patent Document 7] Japanese Patent Laid-Open No. 10-247745 [Patent Document 8] Japanese Patent Laid-Open No. 1 0-247760 [Patent Document 9] Japanese Patent Laid-Open No. 1 0-24776 1 [Non-patent Document 1] Edited by Akasaki Yong, "IIIII Nitride Semiconductor (Advanced Electronics 1-21)", first edition, Pui Fung Museum, December 8, 1999, p.285-293 [Non-Patent Document 2]
Isamu Akasaki 等，“EFFECTS OF AIN BUFFER LAYER ON CRYSTALLOGRAPHIC STRUCTURE AND ON ELECTRICAL AND OPTICAL PROPERTIES OF GaN AND Ga!_xAlxN(0<X ^ 0.4) FILMS GROWN ON SAPPHIRE SUBSTARTE BY MOVPE”，（荷蘭）Journal of Crystal Growth，1 989 年，第 98 卷，p.209-2 1 9 〔非專利文獻3〕Isamu Akasaki et al., "EFFECTS OF AIN BUFFER LAYER ON CRYSTALLOGRAPHIC STRUCTURE AND ON ELECTRICAL AND OPTICAL PROPERTIES OF GaN AND Ga! _XAlxN (0 < X ^ 0.4) FILMS GROWN ON SAPPHIRE SUBSTARTE BY MOVPE", (Netherlands) Journal of Crystal Growth, 1 989, Volume 98, p.209-2 1 9 [Non-Patent Document 3]
L.T.Romana 等，“STRUCTUAL CHARACTERIZATION (4) 200416831 OF THICK GaN FILMS GROWN BY PHASE EPITAXY”，（美國），Mat· Res. ，1996 年，第 423 卷，p.245-250 【發明內容】 本發明係有鑑於上述情形而完成者 使可充分且穩定地抑制來自111族氮化 錯位之傳播的磷化硼層的結晶構造變ί III族氮化物半導體層和磷化硼層的接 優異的磷化硼系化合物半導體元件。另 其之製造方法。 〔解決課題用之手段〕 本發明人爲了解決上述課題而進行 以下的磷化硼系化合物半導體元件及其 光二極體。 即本發明係： (1 ) 一種磷化硼系化合物半導體 由III族氮化物半導體層和磷化硼層形 之磷化硼系化合物半導體元件，其特徵 化物半導體層的表面爲（〇 . 〇 · 〇 · 1 .)結 層係在上述III族氮化物半導體層的（^ 具有與該結晶面平行堆疊之{ 1 1 1 }結晶 hydride vapor S o c . Symp. Proc. ，目的在於提供： 物半導體層的錯合 靑楚，藉此，具有 面構造之元件特性 外，目的在於提供 檢討的結果，發明 製造方法、以及發 元件’是針對具備 成的異質接面構造 爲·上述III族氮 晶面’上述磷化硼 )結晶面上 面的U 1 1 }-磷化硼 (5) (5)200416831 (2 ) —種（1 )記載之磷化硼系化合物半導體元件’ 其中，上述111族氮化物半導體層係繊維鉢礦結晶型’上 述I π族氮化物半導體層之（0.0.0 · 1 ·)結晶面的〔2·-1.-1 .0 .〕結晶方位和上述磷化硼層的{1 1 1 }結晶面的< 1 1 0 > 結晶方位係平行。 (3 )如（2 )記載之磷化硼系化合物半導體元件，其 中，平行於上述III族氮化物半導體層之（〇.〇.〇. 1.)結晶 面的〔2 · -1 · - 1 . 0 .〕結晶方位之上述磷化硼層的< 1 1 〇〉結 晶方位係2方位存在，其等形成的角度爲180°。 (4 )如（3 )記載之磷化硼系化合物半導體元件，其 中，平行於上述III族氮化物半導體層之（〇.〇 .0.1.)結晶 面的〔2 · - 1 · - 1 · 0 ·〕結晶方位之上述磷化硼層的< 1 1 0 >結 晶方位係〔1.-1.0·〕以及〔-1·1·〇.〕。 (5 )如（1 )至（4 )中任一項所記載之磷化硼系化 合物半導體元件，其中，上述III族氮化物半導體層係（ 0.0 · 0.1 ·) —氮化鎵層，上述磷化硼層係在< 1 1 1 >結晶方 位含有積層缺陷以及/或者雙晶之{ 1 1 1 }-磷化硼層。 (6 )如（1 )至（5 )中任一項所記載之磷化硼系化 合物半導體元件，其中，上述磷化硼層係具有比上述III 族氮化物半導體層小的錯位密度。 另外，本發明係： (7 ) —種磷化硼系化合物半導體元件之製造方法， 是針對具備由III族氮化物半導體層和磷化硼層形成的異 質接面構造之磷化硼系化合物半導體元件之製造方法，其 -8 - (6) (6)200416831 特徵爲具有··以表面爲（0.0.0· 1 .)結晶面之III族氮化物 半導體層爲基底，對於汽相成長區域供應含有砸之化合物 和含有磷之化合物，使具有與上述III族氮化物半導體層 的（0.0 · 0 · 1 ·)結晶面平行堆疊之{ 1 1 1 }結晶面的{ 1 1 1 }-磷 化硼層汽相成長之工程。 (8 )如（7 )記載之磷化硼系化合物半導體元件之製 造方法，其中，在75 0 °C以上1 200°C以下的溫度，使上述 磷化硼層汽相成長。 (9 )如（7 )或（8 )記載之磷化硼系化合物半導體 元件之製造方法，其中，以600以上的V/III比率，使上 述磷化硼層汽相成長。 另外，在本說明書中，「V/III比率」係意指含有磷 之化合物（磷原料）中的磷原子濃度對於供應給汽相成長 區域之含有硼之化合物（硼原料）中的硼原子濃度之比率 〇 另外，本發明係： (1 0 ) —種發光二極體，是針對具備：依序積層下部 包覆層，及發光層，及保護該發光層之保護層，及上部包 覆層所形成的積層體之發光二極體，其特徵爲：上述保護 層係由表面設爲（0·0·0·1·)結晶面之III族氮化物半導體 層所形成，而且，上述上部包覆層係由在上述保護層的（ 0 · 0 · 0 · 1 ·)結晶面上具有與該結晶面平行堆疊之{ 1 1 i }結晶 面的{1 1 1 }-磷化硼層所形成。 (7) (7)200416831 【實施方式】 以下，詳細說明本發明。 〔磷化硼系化合物半導體元件〕 本發明之磷化硼系化合物半導體元件係具備由I π族 氮化物半導體層和磷化硼層所形成的異質接面構造，其特 徵爲III族氮化物半導體層和磷化硼層的結晶構造。 構成磷化硼層的基底之III族氮化物半導體層的化合 物，例如以氮化鎵（GaN )、氮化鋁·鎵（AlxGanNiOS X S 1 )等之組成式 AlxGaYInzN(0 S X、Y、z $ 1， X + Y + Z=l)所表示的化合物爲適當。另外，在氮（n )之外 ，含有其他第V族元素（例如，磷（Ρ )或砷（as )等） 化合物，例如，組成式 AlxGaYlnzNQMhQMS X、γ、i ，X + Y + Z= l，0<QS1，Μ爲氮以外的第V族元素）所表示 的化合物等也適當。 本發明之磷化硼系化合物半導體元件係III族氮化物 半導體層的表面爲（0 · 0.0 · 1 ·)結晶面，在該結晶面上接 合磷化硼層而形成。另外，在本發明中，磷化硼層係具有 與III族氮化物半導體層的（0·0·0· 1.)結晶面平行堆疊之 { 1 1 1 }結晶面的{ 1 1 1 } 一磷化硼層。藉由採用此種構造，可 以獲得錯合錯位等少之良質的磷化硼層。 此係單體的磷化硼的{1 1 1 }結晶晶格面的間隔（晶格 面間隔）和III族氮化物半導體的（0·0·0·1·)結晶面的a 軸晶格常數幾乎一致故，在ΙΠ族氮化物半導體層的（ (8) (8)200416831 0.0.0.1 .)結晶面上可以使起因於晶格失配之錯合錯位等 少的良質之{111}-磷化硼層成長。 例如，相對於單體的磷化硼結晶的晶格面間隔爲 0.320nm，氮化鎵（G aN )的a軸晶格常數爲〇 · 3 1 8 nm，氮 化鋁（A1N )的a軸晶格常數爲〇·3 1 lnm (關於a軸晶格 常數，請參考寺本巖著「半導體裝置槪論」’初版，（ 珠）培風館，1 995年3月20日，ρ·28 )。如此，III族氮 化物半導體的（〇 . 〇 . 〇 . 1 .)結晶面的a軸晶格常數和磷化 硼之{ 1 1 1 }結晶面的晶格面間隔的晶格失配，在GaN中幾 乎不存在，對於A1N，也不過高2.8%，可以在III族氮化 物半導體的（〇.〇.0.1.)結晶面上使良質的磷化硼層成長 〇 依據第1圖，舉III族氮化物半導體層由纖維鋅礦結 晶型的氮化鎵單結晶所形成時，就本發明具體做說明。第 1圖係模型地顯示纖維鋅礦結晶型的氮化鎵單結晶之（ 0 · 0.0.1 ·)結晶面，以及形成在其上之磷化硼結晶的排列 樣子平面圖。 氮化鎵單結晶的（0 · 0 · 0 · 1 ·)結晶面1係由多數的平 面視圖爲正六角形的單位胞（單位平面結晶晶格）1 a緻 密排列所構成。在本發明中，在該結晶面1上與該結晶面 1平行堆疊磷化硼的{111}單晶體2 ( 2a以及2b),使之 在氮化鎵和磷化硼之間可以發揮良好的晶格匹配。 氮化鎵和磷化硼之間的晶格匹配變得最好是，磷化硼 的{ 1 1 1 }結晶面的< 1 1 0 >結晶方位與氮化鎵之（〇 . 〇 . 〇 . 1 . -11 - (9) (9)200416831 )結晶面1的〔2 . - 1 . - 1 . 0 .〕結晶方位成爲平行而配置磷化 硼的{ 1 1 1 }結晶面時。此係氮化鎵的（0 · 0.0 . 1 .)結晶面1 的a軸晶格常數（第1圖中，以符號a表示）和磷化硼的 { 1 1 1 }結晶面的{ 1 1 〇 }晶格面的間隔幾乎一致的緣故。 特別是如配置正面視圖正三角形的磷化硼之{ 1 1 1 }-結 晶體2 a以及2b使得氮化鎵的〔2 · - 1 · - 1 . 〇 .〕結晶方位和磷 化硼的〔1 · - 1 . 〇 .〕或者〔-1 . 1 . 〇 _〕結晶方位成爲平行時， 則可以獲得優異品質的{1 1 1} 一磷化硼層。此處，〔1.-1 · 0 ·〕結晶方位和〔-1 . 1 . 0 .〕結晶方位係相互角度有1 8 0 ° 不同之方向。另外，在第1圖中，氮化鎵的〔2.-1.-1.0.〕 結晶方位和〔1 · -1. 〇 .〕結晶方位存在平行關係的是磷化硼 接晶體2a’風化纟豕的〔2.-1.-1.0.〕結晶方位和〔-1.1.0. 〕結晶方位存在平行關係的是磷化硼結晶體2b。藉由組 合相互頂點方向有1 80 °不同之{ 1 1 1 } 一結晶體2a和2b而 使之聚集，可以構成與氮化鎵的（〇 · 〇 . 〇 . 1 .)結晶面匹配 而整體呈現平面視圖正六角形的{ 1 11 } -磷化硼結晶層。 〔磷化硼系化合物半導體元件之製造方法〕 上述之本發明的磷化硼系化合物半導體元件例如可以 III族氮化物半導體層爲基底，將含有硼之化合物和含有 磷之化合物供應給汽相成長區域，藉由汽相成長法在特定 條件下使磷化硼層成長而製造。汽相成長法可舉··有機金 屬汽相磊晶（MOVPE)法、鹵素（halogen) VPE法、氮 化（hydride) VPE法、分子束磊晶（MBE)法等。 (10) (10)200416831 此處，爲了獲得由與構成上述之六方晶格的111族氮 化物半導體層之（0 · 0.0.1 ·)結晶面的平面視圖正六角形 的單位胞形狀一致而規則性排列整齊的多數平面視圖正三 角形的{ 1 1 1 }結體所形成的{ 1 1 1 }憐化硼結晶層，以滿足 以下條件（A )〜（G )爲佳。 (A )在使{ 1 1 1 } 一磷化硼結晶層汽相成長時，基底之 111族氮化物半導體層（例如，氮化鎵結晶層）的表面需 要爲由（0 · 0.0 · 1 .)結晶面所形成的單結晶面。 (B) III族氮化物半導體層之（〇.〇·〇」.）單結晶表 面的傾斜角度，以在設（0 · 0 · 0.1 ·)結晶面爲水平面時， 其角度爲± 5 °以內爲佳。在由（0. 〇. 〇 . 1 .)結晶面傾斜超 過5 °的單結晶表面中，構成結晶的原子排列和{ 1 1 1 } 一磷 化硼接晶的{ 1 1 〇 }晶格面的間隔差異增大故，難於穩定形 成平面視圖正三角形的{ 1 1 1 } -磷化硼結晶體如第1圖般 整齊規則排列之{ 1 1 1 } 一磷化硼結晶層。 (C) 爲了有效發揮作爲汽相成長磷化硼結晶層之基 底的功能，以將III族氮化物半導體層的表面維持在化學 量論幾乎舉得均衡之組成爲佳。例如，在汽相成長磷化硼 結晶層時，如將III族氮化物半導體層保持在高溫時，則 構成III族氮化物半導體層之第V族元素揮發，在III族 氮化物半導體層的表面中，第III族元素對於第V族元素 相對成爲豐富時，爲了維持化學量論幾乎取得均衡之（ 〇.〇. 0.1.)結晶面，以採取將III族氮化物半導體層在過多 包含氨（NH3 )或者聯胺（N2H2 )類等含氮化合物之環境 (11) (11)200416831 中予以升溫等措施爲佳。 (D )以在7 5 0 °C以上1 2 0 0 °C以下的溫度中，使磷化 硼結晶層汽相成長爲佳。在成膜溫度（基底的溫度）低於 7 5 0 °C時，難於穩定獲得磷化硼的{ Π 1 }單結晶層，在超過 1 200 °C時，導致B1SP2等之磷化硼多量體的產生，難於穩 定獲得單體的磷化硼。另外，在獲得η型{ 1 1 1 } -磷化硼 單結晶層時，成膜溫度以7 5 0 °C〜約1 000 °C爲佳，在獲得 p型{ 1 1 1 } 一磷化硼結晶層時，成膜溫度以約1 〇 〇 〇。〇〜 1 2 0 (TC 爲佳。 (E )在使磷化硼結晶層汽相成長時的V/III比率， 以設爲6 0 0以上爲佳，設爲1 0 0 0〜2 0 0 〇則更好。 (F )在使磷化硼結晶層汽相成長前，事先使原料氣 體（含有硼之化合物以及含有磷之化合物）流通於汽相成 長區域，在汽相成長區域中，使與原料氣體接觸部份的表 面形成含磷和硼之被膜爲佳。被膜的厚度並無特別限制， 以1 0 0 n m程度即足夠。 (G )在使磷化硼結晶層汽相成長時，表面以調整使 得原料氣體之含有硼之化合物和含有磷之化合物時間上幾 乎同時到達載置於汽相成長區域之ΠΙ族氮化物半導體層 的表面爲佳。原料氣體到達ΠΙ族氮化物半導體層之時間 可藉由載送（carrier )氣體的流量而調整。「載送氣體」 係擔任將原料氣體運送於汽相成長區域之功能的氣體，可 由高純度的氫（Η 2 )或氮（N 2 )以及氬（Ar )等惰性氣 體，以及含彼等之混合氣體等構成。容許之原料氣體的到 -14- (12) (12)200416831 達時間差例如在5 0nm/f分鐘的成長速度下，使{丨丨丨} 一磷 化硼結晶層汽相成長時，約爲5秒。另外，到達時間雖然 幾乎同時，但是有些許差異時，如調整運送氣體的流量以 使揮發性高的第V族元素的原料（含有磷之化合物）在 時間上比第ΙΠ族元素的原料（含有硼之化合物）先到達 ΠΙ族氮化物半導體層的表面時，則{ 1 1 1 } -磷化硼結晶層 更容易形成，更爲合適。 在III族氮化物半導體層的（0.0.0.1 .)結晶面上是否 形成具有定向性的{ 1 1 1 } -磷化硼結晶層，可以藉由X射 線繞射或者電子束繞射的繞射影像而判定。 在III族氮化物半導體層的（0.0.0.1.)結晶面上成長 { 1 1 1 } 一磷化硼結晶層時，特別是{ 1 1 1 } 一磷化硼結晶層的 層厚幾乎未滿5 00nm之薄膜層時，在X射線繞射影像中 會明確出現由於III族氮化物半導體結晶的（〇.〇. 0.1.)結 晶面和磷化硼的{ 1 1 1 }結晶面所導致的布拉格（Bragg )繞 射峰値。 在電子束繞射影像中，於連結起因於III族氮化物半 導體層的（〇.〇·〇·〗·）結晶面之繞射斑點（spot)的直線上 ’出現起因於磷化硼結晶層的{ 1 1 1 }結晶面之繞射斑點。 另外，在使射入電子束的方向爲< 1 1 0 >時，可以獲得由一 頂點的方向爲1 8 0 °不同之{ 1 1 1 } 一磷化硼結晶，即以 < 1 1 0>結晶軸爲中心左右對稱定向的{ 1 1 1丨一磷化硼結晶成 爲1 8 0 °反轉關係的{ 1 1 〇 }結晶面的反晶格影像。 在本發明的磷化硼系化合物半導體元件中，係設爲設 -15- (13) (13)200416831 置以III族氮化物半導體層的（〇.〇.〇· 1·)結晶面爲基底以 使磷化硼結晶層汽相成長’規則而整齊地排列之{1 11 } -磷化硼結晶之構造故，抑制由基底之錯位的傳播效果，可 以高程度而且穩定地得到發揮。其結果爲，可以提供磷化 硼結晶層具有比III族氮化物半導體層小的錯位密度之磷 化硼系化合物半導體元件。 特別是，使ΠΙ族氮化物半導體層的（〇.〇.0.1.)結晶 面之〔2 · - 1 . - 1 · 0 ·〕結晶方位和磷化硼結晶層的< 1 1 〇>結晶 方位成爲平行的結晶配置，可以穩定獲得與III族氮化物 半導體層的（〇. 〇. 0.1.)結晶面良好匹配的{11 i} 一磷化硼 結晶層，極爲合適。 例如設置在氮化鎵的（〇 · 〇 . 〇 . 1 .)結晶面上之{ 1 1 1 } 一 磷化硼結晶層在兩層的接面界面阻止來自氮化鎵的錯位傳 播，其本身成爲1 X 1 03/cm2以下的低錯位密度的結晶層 。在此種低錯位密度的磷化硼結晶層的內部中，在磷化硼 的<111>結晶方位含有積層缺陷（stacking fault)以及/ 或者雙晶（twinning )，此係其特徵。積層缺陷或雙晶吸 收錯位的結果，乃導致錯位密度減少。 如上述般，如依據本發明，藉由磷化硼結晶層，可以 充分且穩定抑制來自基底的錯位傳播故，可以提供洩漏電 流少’得以發揮良好的整流特性之元件特性優異的磷化硼 系化合物半導體元件。 在本發明之磷化硼系化合物半導體元件中，具有如上 述特性的{ 1 1 1 } -磷化硼結晶層可以有效利用作爲避免元 -16- (14) 200416831 件驅動電流介由錯位之短路的機能層。例如，與π〗族氮 化物半導體層異質接面的低錯位密度之{ 1 1 1 } 一磷化硼結 晶層可以利用作爲形成不伴隨因短路所致的耐壓不良之歐 姆（Ο h m i C )電極用的接觸（c 〇 n t a c t )層。另外，可以利 用作爲形成閘極（gate )電流的短路洩漏（leak )受到抑 制的簫特基（Schottky )接面型閘極電極用的接觸層。 〔實施例〕LTRomana et al., "STRUCTUAL CHARACTERIZATION (4) 200416831 OF THICK GaN FILMS GROWN BY PHASE EPITAXY", (United States), Mat · Res., 1996, Vol. 423, p.245-250 [Content of the Invention] The present invention has In view of the above circumstances, the finisher changed the crystal structure of the boron phosphide layer which can sufficiently and stably suppress the propagation of the group 111 nitride dislocations. The group III nitride semiconductor layer and the boron phosphide layer have excellent boron phosphide systems. Compound semiconductor element. Another manufacturing method. [Means for solving problems] In order to solve the above problems, the present inventors performed the following boron phosphide-based compound semiconductor devices and their photodiodes. That is, the present invention is: (1) A boron phosphide-based compound semiconductor is composed of a group III nitride semiconductor layer and a boron phosphide-based compound semiconductor element in the form of a boron phosphide layer, and the surface of the characteristic compound semiconductor layer is (0. 〇 · 〇 · 1.) The junction layer is (^ has {1 1 1} crystalline hydride vapor S oc. Symp. Proc.) Stacked in parallel with the group III nitride semiconductor layer, and aims to provide: a semiconductor layer In this way, in addition to the characteristics of the device with surface structure, the purpose is to provide the results of the review, the invention of the manufacturing method, and the device 'is for the completed heterojunction structure to the above-mentioned group III nitrogen crystal plane' The above boron phosphide) U 1 1} -boron phosphide (5) (5) 200416831 (2) —the boron phosphide-based compound semiconductor device according to (1) above, wherein the group 111 nitride semiconductor described above Layer system 繊 Werbite crystal type 'The crystal orientation of [2 · -1.-1.0.] In the (0.0.0 · 1 ·) crystal plane of the above-mentioned I π group nitride semiconductor layer and the { 1 1 1} crystal plane < 1 1 0 > crystal orientation is parallel(3) The boron phosphide-based compound semiconductor device according to (2), wherein [2 · -1 ·-1 is parallel to the (0.0.0.0. 1.) crystal plane of the group III nitride semiconductor layer. 0.] The crystal orientation of the above boron phosphide layer is <1 1 〇> The crystal orientation exists in 2 orientations, and the angle formed by them is 180 °. (4) The boron phosphide-based compound semiconductor device according to (3), wherein [2 ·-1 ·-1 · 0 is parallel to the (.0.0.0.1.) Crystal plane of the group III nitride semiconductor layer. ·] Crystal orientation The < 1 1 0 > crystal orientation of the boron phosphide layer is [1.-1.0 ·] and [-1 · 1 · 〇.]. (5) The boron phosphide-based compound semiconductor device according to any one of (1) to (4), wherein the group III nitride semiconductor layer system (0.0 · 0.1 ·)-a gallium nitride layer, the phosphorus The boron-based layer contains a {1 1 1} -boronized phosphide layer in the < 1 1 1 > crystal orientation and includes lamination defects and / or twin crystals. (6) The boron phosphide-based compound semiconductor device according to any one of (1) to (5), wherein the boron phosphide layer system has a smaller dislocation density than the group III nitride semiconductor layer. In addition, the present invention is: (7) A method for manufacturing a boron phosphide compound semiconductor device, which is directed to a boron phosphide compound semiconductor having a heterojunction structure formed of a group III nitride semiconductor layer and a boron phosphide layer. The method for manufacturing a device is characterized in that -8-(6) (6) 200416831 has a group III nitride semiconductor layer with a surface of (0.0.0 · 1.) Crystal plane as a base, and is supplied to a vapor phase growth region. A compound containing phosphorous and a compound containing phosphorus, which has {1 1 1} -phosphorus having a {1 1 1} crystal plane stacked in parallel with the (0.0 · 0 · 1 ·) crystal plane of the group III nitride semiconductor layer described above Vapor phase growth engineering of boron layer. (8) The method for producing a boron phosphide-based compound semiconductor device according to (7), wherein the boron phosphide layer is vapor-grown at a temperature of from 75 ° C to 1200 ° C. (9) The method for producing a boron phosphide-based compound semiconductor device according to (7) or (8), wherein the boron phosphide layer is vapor-grown at a V / III ratio of 600 or more. In addition, in this specification, "V / III ratio" means the concentration of the phosphorus atom in the compound containing phosphorus (phosphorus raw material) with respect to the boron atom concentration in the compound containing boron (boron raw material) supplied to the vapor phase growth region. The ratio 〇 In addition, the present invention is: (1 0)-a light emitting diode, which is directed to: sequentially stacking a lower cladding layer and a light emitting layer, and a protective layer to protect the light emitting layer, and an upper cladding layer The formed light-emitting diode of the multilayer body is characterized in that the protective layer is formed of a group III nitride semiconductor layer whose surface is a (0 · 0 · 0 · 1 ·) crystal plane, and the upper package is The cladding layer is formed of a {1 1 1} -boron phosphide layer having a {1 1 i} crystal plane stacked in parallel with the crystal plane on the (0 · 0 · 0 · 1 ·) crystal plane of the protective layer. . (7) (7) 200416831 [Embodiment] Hereinafter, the present invention will be described in detail. [Boron Phosphide-Based Compound Semiconductor Device] The boron phosphide-based compound semiconductor device of the present invention has a heterojunction structure formed of a I π group nitride semiconductor layer and a boron phosphide layer, and is characterized by a group III nitride semiconductor. The crystalline structure of the layer and the boron phosphide layer. The compound of the group III nitride semiconductor layer constituting the base of the boron phosphide layer is, for example, a composition formula of AlxGaYInzN (0 SX, Y, z $ 1) such as gallium nitride (GaN), aluminum nitride gallium (AlxGanNiOS XS 1), etc. The compound represented by X + Y + Z = 1) is suitable. In addition, in addition to nitrogen (n), compounds containing other Group V elements (for example, phosphorus (P) or arsenic (as), etc.), for example, the composition formula AlxGaYlnzNQMhQMS X, γ, i, X + Y + Z = l 0 < QS1, where M is a Group V element other than nitrogen) and the like are also suitable. The surface of the boron phosphide-based compound semiconductor element-based group III nitride semiconductor layer of the present invention has a (0 · 0.0 · 1 ·) crystal plane, and a boron phosphide layer is formed on the crystal plane. In addition, in the present invention, the boron phosphide layer has a {1 1 1} crystal plane {1 1 1} that is parallel to the (0 · 0 · 0 · 1.) crystal plane of the group III nitride semiconductor layer. Boron phosphide layer. By adopting such a structure, it is possible to obtain a good quality boron phosphide layer with few misalignments and dislocations. The {1 1 1} crystal lattice plane interval (lattice plane interval) of the boron phosphide of this system and the a-axis lattice of the (0 · 0 · 0 · 1 ·) crystal plane of the group III nitride semiconductor The constants are almost the same. Therefore, on the ((8) (8) 200416831 0.0.0.1.) Crystal plane of the group III nitride semiconductor layer, good quality {111}- The boron phosphide layer grows. For example, the lattice plane spacing of the boron phosphide crystal with respect to the monomer is 0.320 nm, the a-axis lattice constant of gallium nitride (G aN) is 0.318 nm, and the a-axis of aluminum nitride (A1N) is The lattice constant is 0.31 lnm (for the a-axis lattice constant, please refer to Terayan Iwa's "Semiconductor Device Theory" 'First Edition, (Pearl) Peifeng Pavilion, March 20, 1995, ρ · 28). In this way, the lattice mismatch between the a-axis lattice constant of the (〇. 〇. 〇. 1.) Crystal plane of the III-nitride semiconductor and the {1 1 1} crystal plane of boron phosphide is in GaN is almost absent. For A1N, it is not too high by 2.8%. A good boron phosphide layer can be grown on the (.0.0.0.1.) Crystal plane of a group III nitride semiconductor. According to the first figure, take III When the group nitride semiconductor layer is formed of a gallium nitride single crystal of a wurtzite crystal type, the present invention will be specifically described. Fig. 1 is a plan view schematically showing the (0 · 0.0.1 ·) crystal plane of the wurtzite crystal-type gallium nitride single crystal and the arrangement of boron phosphide crystals formed thereon. The (0 · 0 · 0 · 1 ·) crystal plane 1 of the gallium nitride single crystal is composed of a dense array of unit cells (unit plane crystal lattices) 1 a in which most plane views are regular hexagons. In the present invention, {111} single crystal 2 (2a and 2b) of boron phosphide is stacked on the crystal plane 1 in parallel with the crystal plane 1, so that it can develop a good crystal between gallium nitride and boron phosphide. Grid match. The lattice matching between gallium nitride and boron phosphide becomes the best. The < 1 1 0 > crystal orientation of the {1 1 1} crystal face of boron phosphide is the same as that of gallium nitride. 〇. 1. -11-(9) (9) 200416831) When the [2.-1.-1. 1.0.] Crystal orientation of crystal plane 1 becomes parallel and the {1 1 1} crystal plane of boron phosphide is arranged. The a-axis lattice constant of the (0 · 0.0. 1.) Crystal plane 1 of this gallium nitride (indicated by the symbol a in the first figure) and the {1 1 1} crystal plane of boron phosphide {1 1 〇} Because the spacing of the lattice planes is almost uniform. In particular, the {1 1 1} -crystals 2 a and 2 b of boron phosphide with equilateral triangles in front view are configured such that the [2 ·-1 ·-1. 1.0.] Crystal orientation of gallium nitride and [1 ·-1. 〇.] Or [-1. 1. 〇_] When the crystal orientations are parallel, a {1 1 1} boron phosphide layer of excellent quality can be obtained. Here, the [1.-1 · 0 ·] crystal orientation and the [-1. 1. 1.0.] Crystal orientation are directions that are 180 ° different from each other. In addition, in Figure 1, the [2.-1.-1.0.] Crystal orientation of gallium nitride and the [1 · -1.〇.] Crystal orientation have a parallel relationship is the boron phosphide-connected crystal 2a 'weathered plutonium. The [2.-1.-1.0.] Crystal orientation of thorium and the [-1.1.0.] Crystal orientation have a parallel relationship with each other is the boron phosphide crystal 2b. By combining {1 1 1} crystals 2a and 2b that are 180 ° different from each other in their apex directions, the crystals 2a and 2b can be aggregated to form a (0 · 〇. 〇. 1.. A plan view of a regular hexagonal {1 11} -boron phosphide layer. [Manufacturing method of boron phosphide-based compound semiconductor device] The above-mentioned boron phosphide-based compound semiconductor device of the present invention may be based on a group III nitride semiconductor layer, for example, and a compound containing boron and a compound containing phosphorus may be supplied to the vapor phase for growth. The region is manufactured by growing a boron phosphide layer under a specific condition by a vapor phase growth method. Vapor phase growth methods include organic vapor phase epitaxy (MOVPE) method, halogen VPE method, hydrogenated VPE method, and molecular beam epitaxy (MBE) method. (10) (10) 200416831 Here, in order to obtain a regular hexagonal unit cell shape consistent with the plan view of the (0 · 0.0.1 ·) crystal plane of the 111-nitride semiconductor layer constituting the hexagonal lattice described above, The regular {1 1 1} structure formed by the {1 1 1} junctions of regular triangles with regular arrangement is suitable to satisfy the following conditions (A) ~ (G). (A) When the {1 1 1} boron phosphide crystal layer is grown in a vapor phase, the surface of the group 111 nitride semiconductor layer (for example, a gallium nitride crystal layer) of the substrate needs to be (0 · 0.0 · 1. ) A single crystal plane formed by a crystal plane. (B) The inclination angle of the (.00 · 〇 ".) Single crystal surface of the group III nitride semiconductor layer is such that when the (0 · 0 · 0.1 ·) crystal plane is a horizontal plane, the angle is within ± 5 ° Better. In a single crystal surface whose (0. 〇. 〇. 1.) Crystal surface is inclined more than 5 °, the atomic arrangement constituting the crystal and the {1 1 〇} lattice plane of {1 1 1} boron phosphide crystal The interval difference increases, so it is difficult to form a {1 1 1} -boron phosphide crystal layer with regular and regular arrangement of {1 1 1} -boron phosphide crystals as shown in FIG. 1. (C) In order to effectively function as a substrate for the boron phosphide crystal layer grown in the vapor phase, it is preferable to maintain the surface of the group III nitride semiconductor layer at a stoichiometric composition that is almost balanced. For example, when a boron phosphide crystal layer is grown in the vapor phase, if the group III nitride semiconductor layer is kept at a high temperature, the group V elements constituting the group III nitride semiconductor layer are volatilized, and the surface of the group III nitride semiconductor layer is volatilized. When the Group III element is relatively abundant for the Group V element, in order to maintain the stoichiometry (0.0.0.1.) Crystal plane, the Group III nitride semiconductor layer contains excessive ammonia ( NH3) or hydrazine (N2H2) and other nitrogen-containing compounds in the environment (11) (11) 200416831 and other measures are preferred. (D) It is preferred that the vapor phase of the boron phosphide crystal layer be grown at a temperature of from 750 ° C to 120 ° C. When the film-forming temperature (the temperature of the substrate) is lower than 750 ° C, it is difficult to obtain a stable {Π 1} monocrystalline layer of boron phosphide, and when it exceeds 1 200 ° C, it results in a boron phosphide bulk such as B1SP2 It is difficult to obtain the boron phosphide of the monomer stably. In addition, when the n-type {1 1 1} -boron phosphide single crystal layer is obtained, the film formation temperature is preferably from 7 50 ° C to about 1 000 ° C, and the p-type {1 1 1} monophosphine is obtained. When the boron crystal layer was formed, the film formation temperature was about 1,000. 〇 ~ 1 2 0 (TC is preferred. (E) The V / III ratio when the boron phosphide crystal layer is vapor-grown is preferably set to 60 or more, and is set to 1 0 0 0 to 2 0 0 (F) Before the vapor phase growth of the boron phosphide crystal layer, the source gas (the compound containing boron and the compound containing phosphorus) is circulated in the vapor phase growth area in advance, and in the vapor phase growth area, the It is preferable to form a film containing phosphorus and boron on the surface in contact with the source gas. The thickness of the film is not particularly limited, and it is sufficient to be about 100 nm. (G) When the vapor phase of the boron phosphide crystal layer is grown, The surface is adjusted so that the boron-containing compound and the phosphorus-containing compound of the source gas reach the surface of the group III nitride semiconductor layer placed in the vapor phase growth region almost simultaneously in time. The source gas reaches the group III nitride semiconductor layer. The time can be adjusted by the flow rate of the carrier gas. "Carrier gas" is a gas that functions to transport the raw material gas to the vapor phase growth region, and can be made of high purity hydrogen (的 2) or nitrogen (N 2 ) And inert gases such as argon (Ar), and They are composed of mixed gas, etc. The permissible raw material gas reaches -14- (12) (12) 200416831. For example, at a growth rate of 50 nm / f minutes, the {丨 丨 丨} boron phosphide crystal layer When the vapor phase grows, it is about 5 seconds. In addition, although the arrival times are almost the same, there are some differences, such as adjusting the flow rate of the transport gas so that the raw materials (groups containing phosphorus) of Group V elements with high volatility are within the time When the raw material (compound containing boron) of the group III element reaches the surface of the group III nitride semiconductor layer first, the {1 1 1} -boron phosphide crystal layer is easier to form and is more suitable. Group III nitrogen Whether or not a {1 1 1} -boron phosphide crystal layer having a directional property is formed on the (0.0.0.1.) Crystal surface of the compound semiconductor layer can be determined by a diffraction image of X-ray diffraction or electron beam diffraction. When growing a {1 1 1} monocrystalline boron phosphide layer on the (0.0.0.1.) Crystal surface of a group III nitride semiconductor layer, especially the thickness of the {1 1 1} monopoly boron phosphide layer is almost not full When the film thickness is 5000 nm, it will clearly appear in the X-ray diffraction image. The Bragg diffraction peak 値 caused by the (.0.0. 0.1.) Crystal plane of the group II nitride semiconductor crystal and the {1 1 1} crystal plane of boron phosphide. In the electron beam diffraction image, the On the straight line connecting the diffraction spots of the (0.〇 · 〇 ·〗 ·) crystal plane of the group III nitride semiconductor layer, the {1 1 1} crystal plane of the boron phosphide crystal layer appears. In addition, when the direction of the incident electron beam is < 1 1 0 >, {1 1 1} a boron phosphide crystal which is different from a vertex direction of 180 ° can be obtained, that is, The {1 1 1 丨 monoboron phosphide crystals, which are oriented symmetrically around the <1 1 0 > crystal axis, are inverted lattice images of the {1 1 〇} crystal plane with a 180 ° inversion relationship. In the boron phosphide-based compound semiconductor device of the present invention, it is assumed that -15- (13) (13) 200416831 is provided with a (0.0.0.0 · 1 ·) crystal plane of a group III nitride semiconductor layer as a base. The structure of {1 11} -boron phosphide crystals arranged regularly and neatly to grow the vapor phase of the boron phosphide crystal layer can suppress the propagation effect of dislocation from the substrate, and can be exhibited to a high degree and stably. As a result, a boron phosphide-based compound semiconductor device having a boron phosphide crystal layer having a smaller dislocation density than a group III nitride semiconductor layer can be provided. In particular, the [2 ·-1..-1 · 0 ·] crystal orientation of the (〇.0.1.) Crystal plane of the group III nitride semiconductor layer and the < 1 1 〇 > of the boron phosphide crystal layer were made. The crystal orientation becomes a parallel crystal configuration, and a {11 i} boron phosphide crystal layer that is well matched to the (0.0.0.1.) Crystal plane of the III-nitride semiconductor layer is extremely suitable. For example, {1 1 1} a boron phosphide crystal layer provided on the (0 · 〇. 〇. 1.) Crystal surface of gallium nitride prevents the dislocation propagation from gallium nitride at the interface between the two layers, itself A crystal layer with a low dislocation density of 1 X 1 03 / cm 2 or less. In the interior of such a low dislocation density boron phosphide crystal layer, the < 111 > crystal orientation of boron phosphide contains stacking faults and / or twinning, which is a characteristic of this. As a result of lamination defects or twin crystal absorption dislocations, the dislocation density decreases. As described above, according to the present invention, the boron phosphide crystal layer can sufficiently and stably suppress the dislocation propagation from the substrate. Therefore, it is possible to provide a boron phosphide system having excellent leakage characteristics and low element leakage characteristics. Compound semiconductor element. In the boron phosphide-based compound semiconductor device of the present invention, the {1 1 1} -boron phosphide crystal layer having the above-mentioned characteristics can be effectively used as a short circuit avoiding the element 16- (14) 200416831 driving current through dislocation Functional layer. For example, a {1 1 1} low boron phosphide crystal layer with a low dislocation density at a heterojunction with a π group nitride semiconductor layer can be used to form an ohm (0 hmi C) that is not accompanied by a breakdown voltage caused by a short circuit. Contact (co ntact) layer for electrodes. In addition, a contact layer for a Schottky junction-type gate electrode that suppresses a short-circuit leakage (gate) that forms a gate current can be used. [Example]
接著，說明關於本發明之實施例。 (實施例） 本發明之磷化硼系化合物半導體元件係在堆積於藍寶 石基板上的（0·0.0·1·) —氮化鎵單結晶層的表面使{111} -磷化硼結晶層汽相成長，以製造ρη接面型雙異質（Dh )接面構造的發光二極體（LED)。第2圖係模型地顯示 所製造的LED的剖面構造。 首先’藉由三甲基鎵（（CH3)3Ga) /氨（NH3) ^/氣 (H2)反應系統常壓（略大氣壓）m〇CVD法，在ΐ〇5(Γ(： 下’於以（0·0·0·1·)結晶面爲表面的藍寶石基板ι〇1的 表面上形成由η型（ο.ο.ο.ι )—氮化鎵（GaN )單結晶層 所形成的下部包覆層102。形成下部包覆層1〇2之n型氮 化鎵結晶層的載氣濃度設爲約2 xl018cnT3，層厚設爲3 β m 〇 藉由（CH3)3Ga / 三甲基銦（（CH3)3ln)/ nh3/ H2 反應 -17- (15) (15)200416831 系統常壓（略大氣壓）M0CVD法，在850°C下，於下部 包覆層1 0 2的（〇 · 〇 . 〇 . 1 ·)結晶表面上使由η型（0.0 · 0 · 1 · )一氮化鎵·銦（)所形成的發光層103汽 相成長。形成發光層1 0 3之n型氮化鎵·銦結晶層的載氣 濃度設爲約8 xl〇17cm_3，層厚設爲50nm。 停止對於汽相成長區域的銦原料（（CH3)3In)的供給， 發光層103的成長結束後，將（CH3)3Ga和NH3與載送氣 體的H2 —同繼續流通在汽相成長區域。藉此，接續於發 光層1 〇 3上非摻雜地形成由高電阻的（〇 · 〇 · 〇 . 1 .) -氮化 鎵層所形成的保護層1〇4。保護層104係爲了阻止發光層 1 〇 3的發光強度降低用的層。保護層1 04的載氣濃度設爲 5 xl017cm_3，層厚設爲約 12nm。 保護層104的汽相成長結束後，開始降溫。至降爲 6 0 0 °C的溫度爲止，在汽相成長區域繼繪氨的流通，防止 來自保護層1 04的（0.0.0 . 1 .)結晶表面之氮氣的揮發， 使得可以維持保護層1 04的化學量論的組成。 冷卻至室溫後，將在基板1 上依序積層下部包覆層 102和發光層103和保護層104之積層體由汽相成長區域 疏散於可避免與原料氣體接觸之腔體內。在儲存積層體之 期間，在腔體內流通氫氣。 在如上述疏散積層體之期間，在汽相成長區域流通伴 隨三乙基硼（（C2H5)3B)的蒸氣之氫氣以及隣（PH3)， 在位於汽相成長區域之石英製成長爐的內壁等形成含硼和 憐之被0吴。在1 1 0 0 °C堆積厚度約1 # m的被i吴後，一^面流 (16) (16)200416831 通氫氣，一面將汽相成長區域的溫度降低製室溫附近的溫 度。 之後，將疏散的積層體再度送返汽相成長區域’在氨 (NH3 )和氫（H2 )的混合環境中，由室溫升溫到1025 °C。升溫後，停止NH3對於汽相成長區域的供給，同時 ，將磷原料之膦（PH3 )和硼原料之三乙基硼（GH5 ) 3B) 同時流通於汽相成長區域。爲了使磷原料和硼原料同到達 保護層104的（0.0.0.1.)結晶面，設載送PH3的氫氣載 氣的流量爲9L/分鐘，載送（C2H5) 3B)的蒸氣之氫載氣的 流量爲7L/分鐘。藉此，藉由（C2H5 ) 3B)/ PH3/H2反應 系統常壓 MOCVD法，非摻雜地在保護層 104的（ 0.0.0.1 ·) —氮化鎵（GaN )結晶表面上接面形成由p型磷 化硼層所形成的上部包覆層105。使上部包覆層105 (碟 化硼層）成長時的V/III比率（=PH3/(C2H5)3B濃度比率 )設爲1 000。上部包覆層105 (磷化硼層）的載氣濃度設 爲 2 xl019cnT3，層厚設爲 500nm。 如上述般，獲得由在基板1 0 1上依序積層下部包覆層 102和發光層103和保護層104和上部包覆層1〇5所形成 的積層體200。 進行積層體200的薄片之剖面TEM觀察，在觀察形 成上部包覆層1 05之磷化硼層的結晶構造時，在內部確認 到··在對於保護層1 〇 4的（0 · 0.0 · 1 ·)結晶表面，角度在 70 °方向，即沿著磷化硼的<1 11 >結晶方位，存在有雙晶 (積層缺陷）。 -19- (17) (17)200416831 另外，第3圖係顯示成爲保護層1 〇4的氮化鎵層和成 爲上部包覆層1 0 5的磷化硼層的電子束繞射影像複製圖。 第3圖中，以Ο記號表示來自磷化硼結晶的繞射點，以 •記號表示來自氮化鎵的繞射點。另外，這些記號重疊的 部份係表示來自雙方的結晶之繞射點出現在同一位置。 如圖示般，發現關於氮化鎵的（〇 · 〇. 〇 · 1 ·)結晶面之 繞射的方向和發現關於磷化硼的{1 Π }結晶面之繞射點的 方向係成爲平行，確認到磷化硼的{1 1 1} -結晶面堆疊在 氮化鎵的（0 · 0 · 0 · 1 ·)結晶面上。 另外，在設射入電子束的方向爲氮化鎵的〔2 · - 1 · - 1 . 0 . 〕結晶方位時，出現由磷化硼的< 1 1 0 >結晶方位所見到的 閃鋅礦結晶型的磷化硼之反晶格影像。由此，顯示了氮化 鎵的（0 · 0.0.1 ·)結晶面之〔2 . -1 · -1 . 0 .〕結晶方位和磷化 硼的<1 10>結晶方位係平行。 另外，由磷化硼的< 1 1 〇>結晶方位所見到的反晶格影 像（第3圖中，以虛線所示之長方形c以及d)出現在相 互旋轉1 8 0 °之位置故，顯示了 { Π 1 }—磷化硼層係由方向 相互有180°不同之{1 11} 一磷化硼結晶所構成。 另外，由磷化硼層所形成的上部包覆層1 0 5之錯位密 度係未滿1 X 1 〇 3 c ηΓ 3。此係起因於與藍寶石基板1 01的 晶格失配而產生，由η型氮化鎵層所形成的下部包覆層 1 0 2的內部通過發光層1 〇 3以及保護層1 〇 4而傳播來的錯 位，在由磷化硼層所形成的上部包覆層1 〇 5和保護層1 04 的接面界面被阻止所致。 -20- (18) (18)200416831 進行以上的評價後，在上部包覆層1 〇 5的表面中央部 配置由金·鈹合金（An99質量％、Be 1質量％ )所形成的 直徑130//m之平面視圖圓形的P型歐姆電極106。另一 方面，去除上部包覆層105、保護層104以及發光層103 的一部份，使由η型氮化鎵層形成的下部包覆層1 02露出 ，在此露出面配置η型歐姆電極107。η型歐姆電極107 係由：以下層爲鈦（Ti )，上層爲鋁（A1 )之2層構造的 電極所構成。 如上述般，製造平面視圖一邊約3 00 // m之正方形的 ριι接面型DH構造的LED。在此LED的p型以及η型歐 姆電極106、107間以順向流通20mA之動作電流時的發 光特性，則如下述：Next, an embodiment of the present invention will be described. (Example) The boron phosphide-based compound semiconductor device of the present invention is formed on the surface of a (0 · 0.0 · 1 ·) -gallium nitride single crystal layer deposited on a sapphire substrate so that the {111} -boron phosphide crystal layer is vaporized. Phase growth to produce a light emitting diode (LED) with a ρη junction type double heterostructure (Dh) junction structure. Fig. 2 schematically shows the cross-sectional structure of the manufactured LED. First, by the trimethylgallium ((CH3) 3Ga) / ammonia (NH3) ^ / gas (H2) reaction system at atmospheric pressure (slightly atmospheric pressure) mCVD method, at (0 · 0 · 0 · 1 ·) On the surface of the sapphire substrate with a crystal plane of the surface ι〇1, a lower portion formed by a η-type (ο.ο.ο.ι) -gallium nitride (GaN) single crystal layer is formed. The cladding layer 102. The carrier gas concentration of the n-type gallium nitride crystal layer forming the lower cladding layer 102 is set to about 2 × 1018cnT3, and the layer thickness is set to 3 β m 〇 By (CH3) 3Ga / trimethylindium ((CH3) 3ln) / nh3 / H2 reaction-17- (15) (15) 200416831 system atmospheric pressure (slightly atmospheric pressure) MOCVD method, at 850 ° C, in the lower cladding layer 102 (0 · 〇 〇. 1 ·) The light-emitting layer 103 formed of n-type (0.0 · 0 · 1 ·)-gallium nitride · indium () is vapor-grown on the crystal surface. The n-type nitride of the light-emitting layer 103 is formed. The carrier gas concentration of the gallium-indium crystal layer was set to about 8 × 1017 cm_3, and the layer thickness was set to 50 nm. The supply of indium raw material ((CH3) 3In) to the vapor phase growth region was stopped, and after the growth of the light-emitting layer 103 was completed, (CH3) 3Ga and NH3 continue to circulate with H2 as the carrier gas Vapor phase growth region. As a result, a protective layer 104 formed of a high-resistance (0.0 ··· 0.1.)-Gallium nitride layer is formed on the light-emitting layer 103 in a non-doped manner. Protection The layer 104 is a layer for preventing the reduction of the luminous intensity of the light-emitting layer 103. The carrier gas concentration of the protective layer 104 is set to 5 x 1017 cm_3 and the layer thickness is about 12 nm. After the vapor-phase growth of the protective layer 104 is completed, the temperature is lowered. Until it reaches a temperature of 600 ° C, the ammonia flow is continuously drawn in the vapor phase growth area to prevent the volatilization of nitrogen from the crystal surface of the protective layer (0.0.0. 1.), So that the protection can be maintained. The stoichiometric composition of the layer 104. After cooling to room temperature, the laminated body of the lower cladding layer 102, the light-emitting layer 103, and the protective layer 104 is sequentially laminated on the substrate 1 from the vapor phase growth area to avoid the Inside the chamber where the raw material gas contacts. During the storage of the laminate, hydrogen is circulated in the chamber. During the evacuation of the laminate as described above, hydrogen gas accompanied by vapor of triethylboron ((C2H5) 3B) is circulated in the vapor phase growth region. And neighbor (PH3), in the stone located in the area of vapor phase growth The inner wall of the long furnace is made of boron and quilt, which contains boron and quilt. The quilt with a thickness of about 1 # m is piled up at 1 100 ° C, and the surface flow is (16) (16) 200416831 hydrogen flow. While reducing the temperature of the vapor phase growth region to a temperature near room temperature. After that, the evacuated laminate is returned to the vapor phase growth region again in a mixed environment of ammonia (NH3) and hydrogen (H2) from room temperature Warm up to 1025 ° C. After the temperature is raised, the supply of NH3 to the vapor phase growth region is stopped, and at the same time, phosphine (PH3) of the phosphorus material and triethylboron (GH5) 3B) of the boron material are simultaneously circulated in the vapor phase growth region. In order to make the phosphorus raw material and the boron raw material reach the (0.0.0.1.) Crystal surface of the protective layer 104, the flow rate of the hydrogen carrier gas carrying PH3 is 9 L / min, and the hydrogen carrier gas carrying (C2H5) 3B) vapor is set. The flow rate is 7L / min. Thus, the (C2H5) 3B) / PH3 / H2 reaction system atmospheric pressure MOCVD method was used to form a non-doped junction on the (0.0.0.1 ·) -gallium nitride (GaN) crystal surface of the protective layer 104. An upper cladding layer 105 formed of a p-type boron phosphide layer. The V / III ratio (= PH3 / (C2H5) 3B concentration ratio) when the upper cladding layer 105 (the boron-plated layer) was grown was set to 1,000. The carrier gas concentration of the upper cladding layer 105 (the boron phosphide layer) was set to 2 x 1019cnT3, and the layer thickness was set to 500 nm. As described above, a laminated body 200 formed by sequentially laminating a lower cladding layer 102, a light emitting layer 103, a protective layer 104, and an upper cladding layer 105 on the substrate 101 is obtained in this order. TEM observation of the cross section of the laminate 200, and when the crystal structure of the boron phosphide layer forming the upper cladding layer 105 was observed, it was confirmed internally that (0 · 0.0 · 1 for the protective layer 10) ·) On the crystal surface, the angle is in the direction of 70 °, that is, along the < 1 11 > crystal orientation of boron phosphide, there are twin crystals (laminated defects). -19- (17) (17) 200416831 In addition, Fig. 3 is a reproduction image of an electron beam diffraction image of a gallium nitride layer serving as a protective layer 104 and a boron phosphide layer serving as an upper cladding layer 105. . In Fig. 3, the diffraction point from the boron phosphide crystal is represented by a 0 mark, and the diffraction point from the gallium nitride is represented by a mark. In addition, the overlapping parts of these marks indicate that the diffraction points of crystals from both sides appear at the same position. As shown in the figure, the direction of diffraction of the (〇 · 〇.〇 · 1 ·) crystal plane of gallium nitride was found to be parallel to the direction of the diffraction point of the {1 Π} crystal plane of boron phosphide. It was confirmed that the {1 1 1} -crystal plane of boron phosphide was stacked on the (0 · 0 · 0 · 1 ·) crystal plane of gallium nitride. In addition, when the direction of the incident electron beam is the [2 ·-1 ·-1. 1.0.] Crystal orientation of gallium nitride, a flicker seen from the < 1 1 0 > crystal orientation of boron phosphide appears. Inverse lattice image of crystalline zinc boron phosphide. This shows that the [2. -1 · -1. 0.] Crystal orientation of the (0 · 0.0.1 ·) crystal plane of gallium nitride is parallel to the < 1 10 > crystal orientation of boron phosphide. In addition, the inverse lattice image (the rectangles c and d shown by the dashed lines in FIG. 3) seen from the crystal orientation of < 1 1 〇 > of boron phosphide appears at positions rotated 180 ° from each other. It shows that {Π 1} -boron phosphide layer is composed of {1 11} -boron phosphide crystals whose directions are 180 ° different from each other. The dislocation density of the upper cladding layer 105 formed by the boron phosphide layer is less than 1 X 1 0 3 c ηΓ 3. This is caused by the lattice mismatch with the sapphire substrate 101. The inside of the lower cladding layer 102 formed by the n-type gallium nitride layer is propagated through the light-emitting layer 103 and the protective layer 104. This dislocation is caused by the interface between the upper cladding layer 105 formed by the boron phosphide layer and the protective layer 104 being blocked. -20- (18) (18) 200416831 After the above evaluation, a diameter 130 / formed of a gold-beryllium alloy (An99% by mass and Be1% by mass) is disposed on the central portion of the surface of the upper cladding layer 105. / m is a plan view of a circular P-type ohmic electrode 106. On the other hand, a part of the upper cladding layer 105, the protective layer 104, and the light emitting layer 103 is removed, and the lower cladding layer 102 formed of the n-type gallium nitride layer is exposed, and an n-type ohmic electrode is disposed on the exposed surface. 107. The n-type ohmic electrode 107 is composed of a two-layer electrode having a lower layer of titanium (Ti) and an upper layer of aluminum (A1). As described above, a square rhombus-type DH structure LED having a square shape of about 3 00 // m on one side in plan view is manufactured. The light emission characteristics of the p-type and n-type ohmic electrodes 106 and 107 when an operating current of 20 mA flows in the forward direction are as follows:
(1 )發光顏色：青紫 (2 )發光中心波長：約43 0nm (3 )亮度（晶片狀態）：約7mcd (4 )順向電壓：約3 · 6 V 另外，在P型以及η型歐姆電極106、107之間，通 以反向之1 〇 μ Α的電流時的反向電壓爲1 0V。 在本實施例中，係藉由在成爲保護層104的（ 0.0.0.1 .) —氮化鎵結晶表面上規則而整齊地排列之低電 阻的P型{111}-磷化硼層以構成上部包覆層105故，可 使元件動作電流擴散於發光層1 03的廣泛範圍。另外，也 幾乎沒有確認到介由低錯位密度之{ 1 1 1 } -錯位的局部耐 壓不良（local breakdown)的發生。因此，不會發生起因 •21 - (19) (19)200416831 於介由錯位之元件動作電流的短路流通之發光亮點，由近 視野發光影像確認到，由發光層1 03的略全面帶來均句強 度的發光。如此，在本實施例中，可以獲得耐壓特性優異 ，而且均勻發光強度的元件特性優異之短波長可見發光二 極體。 〔發明效果〕 如以上詳細敘述般，如依據本發明，可以提供充分且 穩定抑制來自 ΠΙ族氮化物半導體層之錯合錯位的傳播， 元件特性優異的磷化硼系化合物半導體元件。 【圖式簡單說明】 第1圖係顯示纖維鋅礦型的氮化鎵單結晶之（ 0 · 0 · 0 . 1 ·)結晶面上的{ 1 1丨} 一磷化硼結晶的排列樣子模型 圖。 第2圖係顯示在關於本發明之實施例中所製造的pn 接面型L E D之剖面構造模型圖。 第3圖係在關於本發明之實施例所獲得之積層體的（ 0 · 0 · 0 · 1 ·) -氮化鎵/ {丨丨丨} 一磷化硼接面構造的電子束繞 射影像的複製圖。 〔符號說明〕 1 :氮化鎵的（0 · 〇 . 〇 · 1 ·)結晶面 2 : { 1 1 1 } -磷化硼結晶體 -22- (20) (20)200416831 1 〇 1 :藍寶石基板 102 :下部包覆層 103 :發光層 1 〇 4 :保護層 1 0 5 :上部包覆層 1 06 : p型歐姆電極 107: η型歐姆電極(1) Luminous color: cyan (2) Luminous center wavelength: about 4300nm (3) Brightness (wafer state): about 7mcd (4) Forward voltage: about 3.6V In addition, in P-type and n-type ohmic electrodes Between 106 and 107, the reverse voltage when a reverse current of 10 μA is passed is 10V. In this embodiment, a low-resistance P-type {111} -boron phosphide layer is arranged on the (0.0.0.1.)-Gallium nitride crystal surface that becomes the protective layer 104 in a regular and orderly manner to form the upper portion. Therefore, the cladding layer 105 can spread the element operating current over a wide range of the light emitting layer 103. In addition, the occurrence of a local breakdown of {1 1 1} -dislocation via a low dislocation density was hardly observed. Therefore, the cause will not occur. • 21-(19) (19) 200416831 The bright spots of short-circuit current flowing through the operating current of the dislocated element are confirmed by the near-field luminescence image, and the uniformity of the light-emitting layer 103 is brought about by the full scale. Sentence intensity glow. In this way, in this embodiment, a short-wavelength visible light-emitting diode that is excellent in withstand voltage characteristics and excellent in device characteristics with uniform light emission intensity can be obtained. [Effects of the Invention] As described in detail above, according to the present invention, it is possible to provide a boron phosphide-based compound semiconductor device that sufficiently and stably suppresses propagation of dislocations from the group III nitride semiconductor layer and has excellent device characteristics. [Brief description of the figure] Figure 1 is a model showing the arrangement of {1 1 丨} boron phosphide crystals on the (0 · 0 · 0. 1 ·) crystal surface of the wurtzite-type gallium nitride single crystal. Illustration. Fig. 2 is a cross-sectional structural model diagram showing a pn junction type LED of the pn junction manufactured in the embodiment of the present invention. Fig. 3 is an electron beam diffraction image of a (0 · 0 · 0 · 1 ·) -gallium nitride / {丨 丨 丨} -boron phosphide junction structure of a laminate obtained in an embodiment of the present invention Copy illustration. [Description of Symbols] 1: (0 .. 〇. 1 ·) crystal plane of gallium nitride 2: {1 1 1}-boron phosphide crystal -22- (20) (20) 200416831 1 〇1: sapphire substrate 102: lower cladding layer 103: luminescent layer 1 〇4: protective layer 1 0 5: upper cladding layer 06: p-type ohmic electrode 107: n-type ohmic electrode
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