TW201327915A - III-nitride light-emitting diode and method of producing the same - Google Patents
III-nitride light-emitting diode and method of producing the same Download PDFInfo
- Publication number
- TW201327915A TW201327915A TW101104230A TW101104230A TW201327915A TW 201327915 A TW201327915 A TW 201327915A TW 101104230 A TW101104230 A TW 101104230A TW 101104230 A TW101104230 A TW 101104230A TW 201327915 A TW201327915 A TW 201327915A
- Authority
- TW
- Taiwan
- Prior art keywords
- gallium nitride
- light
- emitting diode
- nano
- type gallium
- Prior art date
Links
Abstract
Description
本發明係關於一種三族–氮化物發光二極體與其製造方法。The present invention relates to a tri-n-nitride light-emitting diode and a method of fabricating the same.
由於在照明應用上具有極大的潛力,以白光發光二極體為基礎的固態光源獲得許多重視。對於白光二極體而言,可透過控制各種顏色(polychromatic)的發光體(emitter),例如紅、黃、綠、藍等發光體的混合而控制其發光效力與色彩表現。現今,氮化銦鎵(indium gallium nitride, InGaN)化合物半導體成為白光二極體中最具潛力的使用材料。這是由於氮化銦鎵InxGa1-xN (0£x£1)的直接能隙可由近紅外光區域(0.6 eV, InN)被連續調整到近紫外光區域(3.4 eV, GaN),涵蓋整個可見光譜。然而,氮化銦鎵(InGaN)在波長更長的範圍,發光效率會大幅降低,導致其應用受到限制。迄今,高效率的氮化銦鎵(InGaN)發光二極體僅限於藍光區域。因此,整個白光二極體通常是利用黃色磷光劑,例如摻雜有鈰(cerium)的釔鋁石榴石(yttrium aluminum garnet),透過冷光下轉換(luminescence down-conversion)技術,而發出白光。但是,由於史托克斯偏移損失(Stokes shift loss)與有限的色彩表現,利用磷光劑(phosphor)轉換的光源其效率與發光品質仍然不夠完美。再者,市場上亦需要一個可涵蓋全可見光波段的發光體來滿足色彩顯示達最佳化的需求。因此,改善InGaN在更長波段的發光效率是目前的研究主流。特別是,半導體材料在波長介於550 nm至590 nm之間之綠黃光波段,即熟知的「綠黃光能隙」(green-yellow gap),其發光效率有明顯下降的趨勢,然而現今沒有任何半導體材料能在此波段製造出高效率的發光二極體。Due to its great potential in lighting applications, solid-state light sources based on white light-emitting diodes have received much attention. For white light diodes, the luminous efficacy and color performance can be controlled by controlling the mixing of various polychromatic emitters, such as red, yellow, green, and blue illuminants. Nowadays, indium gallium nitride (InGaN) compound semiconductors have become the most potential materials for use in white light diodes. This is because the direct energy gap of indium gallium nitride In x Ga 1-x N (0£x£1) can be continuously adjusted from the near-infrared region (0.6 eV, InN) to the near-ultraviolet region (3.4 eV, GaN). , covering the entire visible spectrum. However, indium gallium nitride (InGaN) has a large reduction in luminous efficiency over a longer wavelength range, resulting in limited application. To date, high efficiency indium gallium nitride (InGaN) light emitting diodes have been limited to the blue light region. Thus, the entire white light diode typically emits white light using a yellow phosphor, such as a yttrium aluminum garnet doped with cerium, through a luminescence down-conversion technique. However, due to the Stokes shift loss and limited color performance, the efficiency and luminescence quality of a light source converted with a phosphor is still not perfect. Furthermore, there is a need in the market for an illuminant that covers the entire visible range to meet the needs of color display optimization. Therefore, improving the luminous efficiency of InGaN in a longer wavelength band is currently the mainstream of research. In particular, semiconductor materials in the green-yellow wavelength range between 550 nm and 590 nm, the well-known "green-yellow gap", have a significant decline in luminous efficiency, but today there is no Semiconductor materials can produce highly efficient light-emitting diodes in this band.
造成同一發光體在不同波長有不同的發光效率的原因,可歸因於晶格結構本身帶有極性,以及氮化銦(InN)與氮化鎵(GaN)之間的晶格係數差異(lattice mismatch),約11%。傳統的高品質InGaN發光二極體,於六方烏采結構(wurtzite crystal structure)之GaN 沿極性c軸(c-axis)方向成長平面式的InGaN/GaN多重量子井結構。因此,所成長之高銦含量的InGaN/GaN多重量子井結構,勢必有高密度的缺陷,以及內部靜電(壓電)場(>1 MV/cm)的問題。內部電場會將電子與電洞的波函數(wave function)分開,造成量子侷限史塔克效應(quantum confined Stark effect,QCSE),使得發光體在長波長範圍時,發光效率無法提高。The reason for the different luminous efficiency of the same illuminant at different wavelengths can be attributed to the polarity of the lattice structure itself and the difference in lattice coefficient between indium nitride (InN) and gallium nitride (GaN) (lattice) Mismatch), about 11%. A conventional high-quality InGaN light-emitting diode grows a planar InGaN/GaN multiple quantum well structure along the polar c-axis in the GaN of the wurtzite crystal structure. Therefore, the indium-rich InGaN/GaN multi-quantum well structure with high indium content is bound to have high-density defects and internal electrostatic (piezoelectric) fields (>1 MV/cm). The internal electric field separates the electron from the wave function of the hole, resulting in a quantum confined Stark effect (QCSE), so that the luminous efficiency cannot be improved in the long wavelength range of the illuminant.
對於低銦含量的藍光InGaN發光二極體而言,利用載子侷限現象(carrier localization phenomenon)與超薄的量子井結構,例如商業產品的InGaN發光二極體或雷射二極體其寬度約2至4 nm,藉此可減輕缺陷密度與QCSE的影響。不幸地,上述方案不能應用在高銦含量的InGaN量子井結構,因其缺乏強的電荷侷限,且具有更大的內部電場。此外,對於極性c-平面(c-plane) InGaN二極體,還有其他與QCSE或量子井結構相關的不利特性,例如,當驅動電流增加,由於內部電場造成載子屏蔽,使發光效率降低,並且其中心波長會往藍光的波長方向移動。因此,如何解決QCSE的問題,成為照明光源發展所亟需克服的問題。For a low indium content blue InGaN light-emitting diode, a carrier localization phenomenon and an ultra-thin quantum well structure, such as a commercial product of an InGaN light-emitting diode or a laser diode, have a width of about 2 to 4 nm, thereby reducing the effects of defect density and QCSE. Unfortunately, the above approach cannot be applied to high indium content InGaN quantum well structures due to their lack of strong charge confinement and a larger internal electric field. In addition, for polar c-plane InGaN diodes, there are other unfavorable characteristics associated with QCSE or quantum well structures. For example, when the drive current is increased, the carrier is shielded by the internal electric field, which reduces the luminous efficiency. And its center wavelength will move toward the wavelength of the blue light. Therefore, how to solve the problem of QCSE has become an urgent problem to be solved in the development of lighting sources.
過去數年已有許多研究致力於克服QCSE效應,例如在各種基板上成長非極性的a-平面(a-plane)或m-平面(m-plane)。然而,非極性的方法有其本身的限制與挑戰,因而,對於「綠黃光能隙」之效率降低問題,仍然沒有最佳解決方案。Many studies over the past few years have been devoted to overcoming the QCSE effects, such as the growth of non-polar a-planes or m-planes on various substrates. However, the non-polar method has its own limitations and challenges. Therefore, there is still no optimal solution to the problem of the efficiency reduction of the "green-yellow energy gap".
本發明的目的在於提供具有更佳效率與性質的發光二極體,且克服習知發光二極體的發光效率降低以及在綠黃光波段效率不佳等問題。此外,提供一種簡單、經濟、有效的發光二極體製造方法。It is an object of the present invention to provide a light-emitting diode having better efficiency and properties, and to overcome the problems of reduced luminous efficiency of the conventional light-emitting diode and poor efficiency in the green-yellow light band. In addition, a simple, economical, and efficient method of fabricating a light emitting diode is provided.
本發明一實施例提供一種可在不使用磷光劑條件下發白光的發光二極體,其包含:一基板;一第一電極位於該基板下方;一N型氮化鎵奈米柱陣列,具有複數個N型氮化鎵奈米柱位於該基板上且與該第一電極歐姆接觸;一或多個氮化銦鎵奈米碟,設置於每個N型氮化鎵奈米柱上;一P型氮化鎵奈米柱陣列,具有複數個P型氮化鎵奈米柱,其中每個P型氮化鎵奈米柱對應一個N型氮化鎵奈米柱,且被設置於每個所對應之N型氮化鎵奈米柱上方的該氮化銦鎵奈米碟的上方;以及一第二電極,與該P型氮化鎵奈米柱陣列歐姆接觸。An embodiment of the present invention provides a light emitting diode capable of emitting white light without using a phosphor, comprising: a substrate; a first electrode located under the substrate; and an N-type gallium nitride nanocolumn array having a plurality of N-type gallium nitride nano columns are disposed on the substrate and are in ohmic contact with the first electrode; one or more indium gallium nitride nanodisks are disposed on each of the N-type gallium nitride nano columns; A P-type gallium nitride nano column array having a plurality of P-type gallium nitride nano columns, wherein each P-type gallium nitride nano column corresponds to an N-type gallium nitride nano column, and is disposed in each Corresponding to the upper portion of the indium gallium nitride nanodisk above the N-type gallium nitride nanocolumn; and a second electrode in ohmic contact with the P-type gallium nitride nanocolumn array.
本發明另一實施例提供一種發光二極體的製造方法,包含:提供一導電基板;形成一第一電極於該導電基板下方;形成一N型氮化鎵奈米柱陣列,其具有複數個N型氮化鎵奈米柱位於該導電基板上且與該第一電極歐姆接觸;形成一或多個氮化銦鎵奈米碟於每個N型氮化鎵奈米柱上;形成一P型氮化鎵奈米柱陣列,其具有複數個P型氮化鎵奈米柱,其中每個P型氮化鎵奈米柱對應一個N型氮化鎵奈米柱,且被形成於每個所對應之N型氮化鎵奈米柱上方的該氮化銦鎵奈米碟的上方;以及形成一第二電極,與該P型氮化鎵奈米柱陣列歐姆接觸。Another embodiment of the present invention provides a method for fabricating a light emitting diode, comprising: providing a conductive substrate; forming a first electrode under the conductive substrate; forming an array of N-type gallium nitride nanopillars having a plurality of An N-type gallium nitride nano column is located on the conductive substrate and is in ohmic contact with the first electrode; forming one or more indium gallium nitride nanodisks on each of the N-type gallium nitride nano columns; forming a P A gallium nitride nano-pillar array having a plurality of P-type gallium nitride nano-pillars, wherein each P-type gallium nitride nano-pillar corresponds to an N-type gallium nitride nanocolumn and is formed in each Corresponding to the upper portion of the indium gallium nitride nanodisk above the N-type gallium nitride nanocolumn; and forming a second electrode in ohmic contact with the P-type gallium nitride nanocolumn array.
以下將詳述本案的各實施例,並配合圖式作為例示。除了這些詳細描述之外,本發明還可以廣泛地施行在其他的實施例中,任何所述實施例的輕易替代、修改、等效變化都包含在本案的範圍內,並以之後的專利範圍為準。在說明書的描述中,為了使讀者對本發明有較完整的了解,提供了許多特定細節;然而,本發明可能在省略部分或全部這些特定細節的前提下,仍可實施。此外,眾所周知的步驟或元件並未描述於細節中,以避免造成本發明不必要之限制。圖式中相同或類似之元件將以相同或類似符號來表示。特別注意的是,圖式僅為示意之用,並非代表元件實際的尺寸或數量,除非有特別說明。The embodiments of the present invention will be described in detail below with reference to the drawings. In addition to the detailed description, the present invention may be widely practiced in other embodiments, and any alternatives, modifications, and equivalent variations of the described embodiments are included in the scope of the present invention, and the scope of the following patents is quasi. In the description of the specification, numerous specific details are set forth in the description of the invention. In addition, well-known steps or elements are not described in detail to avoid unnecessarily limiting the invention. The same or similar elements in the drawings will be denoted by the same or similar symbols. It is specifically noted that the drawings are for illustrative purposes only and do not represent the actual dimensions or quantities of the components unless otherwise specified.
在本發明實施例的方法,將利用矽基板上自組裝的GaN奈米柱陣列當作磊晶樣板,再成長InGaN/GaN奈米柱異質接合結構於奈米柱陣列上,藉此可完成本發明的主要目的。上述方法最主要的特色在於排除了壓電極化效應(piezoelectric polarization effects),因而可形成每個厚達數十奈米(nm)的InGaN奈米碟結構。利用上述方法,本發明實施例示範了整體、無磷光體的白光(多色變化的)奈米柱陣列發光二極體,以及偏振全彩(單色的)單根奈米柱發光二極體。In the method of the embodiment of the present invention, a self-assembled GaN nano-column array on a germanium substrate is used as an epitaxial template, and then an InGaN/GaN nano-column heterojunction structure is grown on the nano-pillar array, thereby completing the present invention. The main purpose of the invention. The most important feature of the above method is that the piezoelectric polarization effects are eliminated, so that each InGaN nanodisk structure having a thickness of several tens of nanometers (nm) can be formed. Using the above method, the embodiment of the present invention demonstrates an overall, phosphor-free white light (multi-color varying) nano-pillar array light-emitting diode, and a polarized full-color (monochromatic) single-nano column light-emitting diode. .
以下將介紹本發明較佳實施例之無磷光體、可發白光的多色奈米柱陣列發光二極體。首先,根據電漿輔助分子束磊晶方法,在一3吋、N型矽(111)基板上,沿者六方烏采(wurtzite)結構的c軸(c-axis)成長垂直自我排列的GaN奈米柱陣列。上述電漿輔助分子束磊晶方法的詳細內容見Chen, H.-Y., Lin, H.-W., Shen, C.-H. & Gwo, S. Structure and photoluminescence properties of epitaxially oriented GaN nanorods grown on Si(111) by plasma-assisted molecular-beam epitaxy. Appl. Phys. Lett. 89, 243105 (2006),其內容併入本文,視為本案說明書的一部分。根據上述方法成長的奈米柱陣列,為無應力(strain-free)、無差排(dislocation-free)缺陷的單結晶結構,其被用來成長具相似晶格結構的無應力InGaN奈米碟。Hereinafter, a phosphor-free, white-emitting multicolor nano column array light-emitting diode of a preferred embodiment of the present invention will be described. Firstly, according to the plasma-assisted molecular beam epitaxy method, a vertically self-aligned GaN naphthalene grows along the c-axis of the wurtzite structure on a 3吋, N-type 矽(111) substrate. Rice column array. For details of the above plasma assisted molecular beam epitaxy method, see Chen, H.-Y., Lin, H.-W., Shen, C.-H. & Gwo, S. Structure and photoluminescence properties of epitaxially oriented GaN nanorods. Appliqué on Si(111) by plasma-assisted molecular-beam epitaxy. Appl. Phys. Lett. 89, 243105 (2006), the contents of which are incorporated herein by reference. The nanopillar array grown according to the above method is a single crystal structure with strain-free and dislocation-free defects, which is used to grow a stress-free InGaN nanodisk with a similar lattice structure. .
圖1a至圖1d顯示根據本發明實施例的發光二極體,其中圖1a為發光二極體的立體圖;圖1b顯示發光二極體被施加20 mA的驅動電流時發出白光的照片,而圖下方顯示在各種驅動電流時的電激發光顯微照片(micro-electroluminescence,EL),其放大倍率為10倍;圖1c顯示發光二極體被施加20 mA的驅動電流時之電激發光顯微照片,其放大倍率為100倍;以及圖1d顯示發光二極體之國際照明委員會(CIE 1931)xy色度圖,其中驅動電流從5 mA增加至25 mA,色溫可保持在自然白光的6000K(由普郎克軌跡顯示)。1a to 1d show a light emitting diode according to an embodiment of the invention, wherein FIG. 1a is a perspective view of a light emitting diode; FIG. 1b shows a photo of white light emitted when a light emitting diode is applied with a driving current of 20 mA, and FIG. The micro-electroluminescence (EL) at various driving currents is shown below with a magnification of 10 times; Figure 1c shows the electro-excitation microscopy of a light-emitting diode when a driving current of 20 mA is applied. The photo has a magnification of 100 times; and Figure 1d shows the International Commission on Illumination (CIE 1931) xy chromaticity diagram of the light-emitting diode, in which the drive current is increased from 5 mA to 25 mA, and the color temperature can be maintained at 6000 K of natural white light ( Displayed by the Planck track).
如圖1a所示,本實施例的發光二極體包含一N型矽基板1、一鈦/金(Ti/Au複合層)電極2設置於矽基板1上、一N型氮化鎵(GaN)奈米柱陣列3由許多N型GaN奈米柱構成並與鈦/金電極歐姆接觸、一或多個氮化銦鎵(InGaN)奈米碟4設置於每個N型GaN奈米柱上、一P型GaN奈米柱陣列5由許多P型GaN奈米柱構成且設置於InGaN奈米碟4上方,其中一個P型GaN奈米柱對應一個N型GaN奈米柱,以及一鎳/金(Ni/Au複合層)電極6與P型GaN奈米柱陣列5歐姆接觸。注意鈦/金電極2可不直接接觸N型GaN奈米柱陣列3,而是透過矽基板1與N型GaN奈米柱陣列3歐姆接觸。另外,鎳/金電極6為透明電極;每個P型GaN奈米柱5具有兩端且靠近透明電極的那一端比另一端寬,此結構有助於避免漏電流。As shown in FIG. 1a, the light-emitting diode of the present embodiment comprises an N-type germanium substrate 1, a titanium/gold (Ti/Au composite layer) electrode 2 disposed on the germanium substrate 1, and an N-type gallium nitride (GaN). The nano column array 3 is composed of a plurality of N-type GaN nano columns and is in ohmic contact with the titanium/gold electrode, and one or more indium gallium nitride (InGaN) nanodiscs 4 are disposed on each of the N-type GaN nano columns. A P-type GaN nano-pillar array 5 is composed of a plurality of P-type GaN nano-pillars and is disposed above the InGaN nano-disc 4, wherein one P-type GaN nano-pillar corresponds to an N-type GaN nano-column, and a nickel/ The gold (Ni/Au composite layer) electrode 6 is in 5 ohmic contact with the P-type GaN nano-pillar array. Note that the titanium/gold electrode 2 may not directly contact the N-type GaN nano-pillar array 3, but may be in 3 ohmic contact with the N-type GaN nano-pillar array through the tantalum substrate 1. Further, the nickel/gold electrode 6 is a transparent electrode; each of the P-type GaN nano-pillars 5 has both ends and the end close to the transparent electrode is wider than the other end, and this structure contributes to avoid leakage current.
上述發光二極體的白色發光,是藉由堆疊在GaN奈米柱p-n異質接合結構中的InGaN奈米碟4來完成所須的混光效果。注意每一個前述的一或多個InGaN奈米碟4是由許多不同發射波長的發光體構成,其平均發射波長可由磊晶時的溫度T與In/Ga的分子束通量(flux)控制。奈米碟可由多個成長溫度組合而成在本實施例,發光二極體具有三個不同成長溫度(T1、T2、T3)所組合成的InGaN 奈米碟,其中有三個T1、一個T2、一個T3的InGaN奈米碟,且其磊晶溫度為T1>T2>T3。在本發明其他實施例,依據發光需求,可有不同數量或組合的InGaN奈米碟。另外,在每兩個InGaN奈米碟之間,設置一GaN阻擋層7。The white light emission of the above-mentioned light-emitting diode is achieved by the InGaN nanodisk 4 stacked in the GaN nano-column pn heterojunction structure. Note that each of the aforementioned one or more InGaN nanodisks 4 is composed of a plurality of illuminants of different emission wavelengths, and the average emission wavelength thereof can be controlled by the temperature T at the time of epitaxy and the molecular beam flux of In/Ga. The nano-disc can be composed of a plurality of growth temperatures. In this embodiment, the light-emitting diode has three different growth temperatures (T1, T2, T3), and three T1, one T2. A T3 InGaN nanodisk with an epitaxial temperature of T1 > T2 > T3. In other embodiments of the invention, different numbers or combinations of InGaN nanodiscs may be available depending on the lighting requirements. In addition, a GaN barrier layer 7 is provided between every two InGaN nanodisks.
對於傳統的平面式InGaN/GaN多重量子井結構,InGaN主動層的厚度限制在2到4 nm。在本發明實施例,由於所成長的奈米碟具有無應力的優點,因此其堆疊成長可控制厚度的奈米碟。例如,每個奈米碟的厚度可介於10至25 nm。另外,奈米碟的數量與位置必須精確的控制,才能獲得如圖1b的白光效果。本實施例所提供的厚InGaN奈米碟提供較大與可調整的主動層,且在高驅動電流時,可減低電子過剩、改善載子捕捉的現象。於本文稍後將提及,厚的奈米碟可有效解決發光二極體效率降低的問題。另外,圖1c顯示本實施例的奈米柱陣列發光二極體,具有發出各種多樣顏色(全彩)光的能力。對於傳統磷光體發光二極體而言,若要能發出各種顏色的光,必須發展出新的全彩磷光體陣列,如果考量其溫度穩定性、量子效率、化學可靠性(chemical robustness),這將會是一個令人氣餒的任務。For conventional planar InGaN/GaN multiple quantum well structures, the thickness of the InGaN active layer is limited to 2 to 4 nm. In the embodiment of the present invention, since the grown nano-disc has the advantage of no stress, the stack is grown to control the thickness of the nano-disc. For example, each nanodisk can have a thickness between 10 and 25 nm. In addition, the number and position of the nano-disc must be precisely controlled to obtain the white light effect as shown in Figure 1b. The thick InGaN nanodisk provided in this embodiment provides a large and adjustable active layer, and at high driving current, the electron excess can be reduced and the phenomenon of carrier capture can be improved. As will be mentioned later in this article, a thick nano-disc can effectively solve the problem of reduced efficiency of the light-emitting diode. In addition, Fig. 1c shows the nanopillar array light-emitting diode of the present embodiment, which has the ability to emit light of various colors (full color). For traditional phosphor light-emitting diodes, to be able to emit light of various colors, a new full-color phosphor array must be developed, if considering temperature stability, quantum efficiency, chemical robustness, It will be a daunting task.
圖2a顯示根據本發明上述實施例的InGaN/GaN奈米柱陣列白光發光二極體,其驅動電流為1 mA至25 mA的電激發光圖譜。如圖,在驅動電流20 mA時,兩個主要發光波峰分別位於藍光頻帶的448 nm以及黃光頻帶的569 nm。如圖,因為驅動電流增加使發光波長往藍光偏移的量,小到足以忽略。此表示本發明實施例的發光二極體的發光體可有效排除QCSE效應。在發光二極體的主動層結構中,成長溫度T1的奈米碟提供藍光發射頻帶、T2奈米碟提供黃光頻帶,而T3奈米碟提供較少的紅光頻帶與黃光頻帶混合。隨著驅動電流增加,無論藍光、黃光頻帶都顯示可以忽略波長的偏移量。由這電激發光圖譜可看出,藍光頻帶與黃光頻帶的混合造成如圖1b所示的白光效果。而相當小的波長偏移表示,InGaN奈米碟發光體的極化效應可以忽略,使得奈米柱陣列發光二極體的色溫,不受驅動電流的影響,如圖1d所示。在藍光頻帶的1.3 nm與黃光頻帶的2.4 nm小偏移量,可能是由於InGaN與GaN間微小的自發極性不匹配(spontaneous polarization mismatch)所致。2a shows an InGaN/GaN nanocolumn array white light emitting diode according to the above embodiment of the present invention, which has an electroluminescence spectrum with a driving current of 1 mA to 25 mA. As shown in the figure, at the driving current of 20 mA, the two main illuminating peaks are located at 448 nm in the blue band and 569 nm in the yellow band. As shown in the figure, the amount of the emission wavelength shifted to the blue light due to the increase in the drive current is small enough to be ignored. This indicates that the illuminant of the light-emitting diode of the embodiment of the present invention can effectively exclude the QCSE effect. In the active layer structure of the light-emitting diode, the nano-disc with the growth temperature T1 provides a blue-light emission band, the T2 nano-disc provides a yellow-light band, and the T3 nano-disc provides a mixture of less red and yellow bands. As the drive current increases, both the blue and yellow bands show an offset that ignores the wavelength. It can be seen from this electroluminescence spectrum that the mixing of the blue band and the yellow band causes a white light effect as shown in Fig. 1b. The relatively small wavelength shift indicates that the polarization effect of the InGaN nano-disc illuminator is negligible, so that the color temperature of the nano-column array illuminating diode is not affected by the driving current, as shown in Fig. 1d. The small offset of 2.4 nm in the blue band and 2.4 nm in the yellow band may be due to a small spontaneous polarization mismatch between InGaN and GaN.
如前所述,在高驅動電流時的效率降低,是現今發展發光二極體的主要障礙。造成效率降低的原因,在學術界引起廣泛討論,並提出一些可能的機制,例如歐格非輻射復合(Auger nonradiative recombination)、載子溢流(carrier overflow)、極性場(polarization fields)、線差排(threading dislocation)等等。而本發明實施例所提供之厚的無應力InGaN/GaN奈米柱異質接合結構可成功克服效率降低的問題。As mentioned earlier, the reduction in efficiency at high drive currents is a major obstacle to the development of light-emitting diodes today. The reasons for the decrease in efficiency have caused extensive discussion in the academic world and proposed some possible mechanisms, such as Auger nonradiative recombination, carrier overflow, polarization fields, and line differences. Threading dislocation and so on. However, the thick stress-free InGaN/GaN nano-column heterojunction structure provided by the embodiments of the present invention can successfully overcome the problem of reduced efficiency.
圖2b顯示在圖2a之兩波峰(448、569 nm)與整體之驅動電流與電激發光強度的關係圖。無論是藍光頻帶(448 nm)或黃光頻帶(569 nm),當驅動電流增加,其電激發光的強度也隨著線性增加,且斜率固定。因此,可證明整體發光二極體所發出的白光,不會受到驅動電流增加而改變。另外,整體發光二極體的電激發光圖譜顯示出發光強度並未衰減。Figure 2b shows the relationship between the two peaks (448, 569 nm) and the overall drive current and the intensity of the electrical excitation light in Figure 2a. Whether it is the blue light band (448 nm) or the yellow light band (569 nm), as the drive current increases, the intensity of the electrical excitation light increases linearly with a fixed slope. Therefore, it can be confirmed that the white light emitted by the entire light-emitting diode is not changed by the increase of the drive current. In addition, the electroluminescence spectrum of the overall light-emitting diode showed that the luminous intensity was not attenuated.
注意圖中的驅動電流只測試到25 mA(電流密度約為53 A/cm2),本實施例的發光二極體其實際驅動電流與電流密度還可遠大於此。為了測量在效率降低前的最大電流密度,本發明另一實施例提供單根奈米柱發光二極體,並測量其光電特性。Note that the driving current in the figure is only tested to 25 mA (current density is about 53 A/cm 2 ), and the actual driving current and current density of the light-emitting diode of this embodiment can be much larger than this. In order to measure the maximum current density before the efficiency is lowered, another embodiment of the present invention provides a single nano-pillar light-emitting diode and measures its photoelectric characteristics.
圖3a顯示根據本發明一實施例之單根InGaN/GaN奈米柱發光二極體在室溫下的電流—電壓(I-V)曲線。如圖,在-10V的時候並沒有漏電流發生。而圖中的插圖顯示該單根奈米柱發光二極體的場發射掃描式電子顯微鏡(FE-SEM)圖譜,以及構造示意圖。如圖,刻度標示(scale bar)為500 nm、單根奈米柱發光二極體的長度約2 μm,其包含直徑90 nm、厚度40nm的單一InGaN奈米碟4。I-V曲線顯示出良好的二極體特性。並且,所製備的單根奈米柱發光二極體沒有漏電流,適合用來測量通過其自身的實際電流密度值。3a shows a current-voltage (I-V) curve for a single InGaN/GaN nanopillar light emitting diode at room temperature, in accordance with an embodiment of the present invention. As shown in the figure, no leakage current occurs at -10V. The inset of the figure shows a field emission scanning electron microscope (FE-SEM) pattern of the single nano column light-emitting diode, and a schematic diagram of the structure. As shown in the figure, the scale bar is 500 nm, and the length of the single-nano column light-emitting diode is about 2 μm, which includes a single InGaN nanodisk 4 having a diameter of 90 nm and a thickness of 40 nm. The I-V curve shows good diode characteristics. Moreover, the prepared single-nano column light-emitting diode has no leakage current and is suitable for measuring the actual current density value through itself.
圖3b顯示根據本發明一些實施例之單根InGaN/GaN奈米柱發光二極體的電激發光圖譜,其中每個發光二極體僅具有單個InGaN奈米碟。如圖譜所示,從單一InGaN奈米碟發出的光皆為單色光,具有窄的光譜頻寬,大約25 nm。顯微鏡圖像(未顯示)顯示,在500 nA的驅動電流下,這些單根奈米柱發光二極體所呈現之具有繞射限制(diffraction-limited)之點光源分別為紫光、藍光、青綠光、綠光、黃光。圖3c顯示圖3a的單根InGaN/GaN奈米柱發光二極體,當驅動電流由100 nA增加至500 nA時,發光波峰維持在475 nm。另外,插圖顯示電激發光強度以及相對外部量子效率(external quantum efficiency,EQE)與驅動電流密度的關係。相對EQE的值是以一固定的集光裝置,在直流電的模式,由電激發光強度除以驅動電流獲得。如插圖所示,當驅動電流的密度增加,相對EQE也會增加。而傳統的發光二極體,相同的EQE增加趨勢,只維持在電流密度小於10 A/cm2。在本實施例,奈米柱的直徑為90 nm,藉此可換算出電流密度值。如插圖所示,本發明實施例的發光二極體,當驅動電流密度達到8000 A/cm2時,EQE效率仍然沒有衰減的跡象。相較於習知的InGaN發光二極體,其驅動電流密度僅約10 A/cm2時,對於某些具有較厚InGaN主動層的發光二極體,其驅動電流密度也只有200 A/cm2。本實施例發光二極體的高驅動電流密度,可歸因於厚達40 nm且無應力的奈米碟結構所致。Figure 3b shows an electroluminescent map of a single InGaN/GaN nanopillar light emitting diode in accordance with some embodiments of the invention, wherein each light emitting diode has only a single InGaN nanodisk. As shown in the figure, the light emitted from a single InGaN nanodisk is monochromatic with a narrow spectral bandwidth of approximately 25 nm. Microscope images (not shown) show that at 500 nA drive current, the single-nano-column LEDs exhibit diffraction-limited point sources of violet, blue, and cyan , green light, yellow light. Figure 3c shows the single InGaN/GaN nanopillar light-emitting diode of Figure 3a with a luminescence peak maintained at 475 nm as the drive current is increased from 100 nA to 500 nA. In addition, the inset shows the relationship between the intensity of the electroluminescence and the relative external quantum efficiency (EQE) and the drive current density. The relative EQE value is obtained by dividing the electric excitation light intensity by the drive current in a direct current mode in a direct current mode. As shown in the illustration, as the density of the drive current increases, the relative EQE also increases. In the case of conventional light-emitting diodes, the same EQE increases, maintaining only a current density of less than 10 A/cm 2 . In this embodiment, the diameter of the nanocolumn is 90 nm, whereby the current density value can be converted. As shown in the inset, in the light-emitting diode of the embodiment of the present invention, when the driving current density reaches 8000 A/cm 2 , the EQE efficiency still shows no sign of attenuation. Compared with the conventional InGaN light-emitting diodes, when the driving current density is only about 10 A/cm 2 , the driving current density is only 200 A/cm for some light-emitting diodes having a thick InGaN active layer. 2 . The high driving current density of the light-emitting diode of this embodiment can be attributed to a nano-disc structure with a thickness of up to 40 nm and no stress.
在一些顯示器的應用,例如背光系統,必須將發光二極體發出的光偏振化,以改善系統效率。對於非極性的m-平面InGaN發光二極體,有文獻指出其在in-plane方向可發出非等方向性(anisotropy)的光,因此有機會被應用於液晶顯示器的背光系統;另外,傳統的極性c-平面InGaN發光二極體卻缺乏此特性。然而,本發明實施例的發光二極體,其極性奈米柱所發出的光,可以是高度偏振化的。圖4a顯示如圖3a的單根InGaN/GaN奈米柱發光二極體,在驅動電流500 nA時的偏振(polarized)電激發光圖譜。圖中曲線A為偏振方向與GaN奈米柱軸方向平行的電激發光強度(電場EEL//c)、曲線B為偏振方向與GaN奈米柱軸方向垂直的電激發光強度(電場EEL⊥c),其中奈米柱軸方向即為六方烏采結構(wurtzite crystal structure)的極性c軸方向。另外,定義偏振比(polarization ratio) ρ為ρ = (I//− I⊥)/( I//+ I⊥),其中I//與I⊥分別為平行與垂直c軸方向的電激發光強度。在計算後獲得偏振比ρ為-0.85。另外,圖4a的插圖顯示100倍放大的顯微鏡圖像。In some display applications, such as backlighting systems, the light emitted by the light-emitting diode must be polarized to improve system efficiency. For non-polar m-plane InGaN light-emitting diodes, it is pointed out that it can emit anisotropy light in the in-plane direction, so there is a chance to be applied to the backlight system of liquid crystal displays; in addition, the conventional Polar c-plane InGaN light-emitting diodes lack this property. However, in the light-emitting diode of the embodiment of the invention, the light emitted by the polar nano-pillar may be highly polarized. Figure 4a shows a polarized electroluminescent pattern of a single InGaN/GaN nanopillar light-emitting diode as in Figure 3a at a drive current of 500 nA. In the figure, curve A is the electric excitation light intensity (electric field E EL //c) whose polarization direction is parallel to the GaN nanocolumn axis direction, and curve B is the electric excitation light intensity (electric field E) whose polarization direction is perpendicular to the GaN nanocolumn axis direction. EL ⊥ c), wherein the direction of the column axis of the nanometer is the polar c-axis direction of the wurtzite crystal structure. In addition, the polarization ratio ρ is defined as ρ = (I // − I ⊥ ) / ( I // + I ⊥ ), where I // and I 为 are the parallel excitation and vertical c-axis directions respectively. strength. The polarization ratio ρ obtained after the calculation was -0.85. In addition, the inset of Figure 4a shows a microscope image of 100x magnification.
圖4b顯示如圖3a的單根InGaN/GaN奈米柱發光二極體,利用極座標表示電激發光強度之二維空間分佈與奈米柱幾何的相對關係。之前所測量的偏振比ρ為-0.85表示單根奈米柱發光二極體發出的光是高度偏振化的,可於圖4b獲得證實。不同於習知極性奈米柱或奈米線(nanowire),本發明實施例的發光二極體可發出高度非等方向性的光,而負偏振比-0.85表示偏振方向是垂直於奈米柱長軸方向。一先前的研究指出,寬度小於100 nm的單根GaN奈米柱內的光限制效應(optical confinement effect)是造成光偏振化的原因。如果根據此理論,偏振比將會是發光波長與奈米柱直徑的函數。但相反地,本發明的實驗結果顯示,偏振光是來自設置於GaN奈米柱中間的InGaN奈米碟結構。另外,負的偏振比顯示,偏振光與發光波長以及InGaN奈米碟的直徑的依存關係微弱。這些特性將有助於任何需要偏振光的應用上。Figure 4b shows a single InGaN/GaN nanopillar light-emitting diode as shown in Figure 3a, using polar coordinates to indicate the relative relationship between the two-dimensional spatial distribution of the electrical excitation light intensity and the geometry of the nanocolumn. The previously measured polarization ratio ρ of -0.85 indicates that the light emitted by the single nanocolumn light-emitting diode is highly polarized and can be confirmed in Figure 4b. Unlike conventional polar nanopillars or nanowires, the light-emitting diodes of the embodiments of the present invention can emit light of a non-isotropic direction, while the negative polarization ratio of -0.85 indicates that the polarization direction is perpendicular to the nanocolumn. Long axis direction. A previous study pointed out that the optical confinement effect in a single GaN nanocolumn with a width of less than 100 nm is responsible for the polarization of light. According to this theory, the polarization ratio will be a function of the wavelength of the luminescence and the diameter of the nanocolumn. Conversely, the experimental results of the present invention show that the polarized light is from an InGaN nanodisk structure disposed in the middle of a GaN nanocolumn. In addition, the negative polarization ratio shows that the dependence of the polarized light on the emission wavelength and the diameter of the InGaN nanodisk is weak. These features will help any application that requires polarized light.
總之,本發明實施例提供的奈米柱陣列發光二極體與單根奈米柱發光二極體,以不同習知技術之厚的、無應力的InGaN奈米碟發光體,克服了現今發光二極體,特別是白光發光二極體的發展限制,例如,在「綠黃光能隙」以及高驅動電流時的效率降低。此外,本發明實施例的發光二極體之製作不需要特殊的奈米製造技術,且具有於半導體基板上大量製造的能力。此外,本發明實施例的InGaN奈米碟之數量、厚度與結構可依照需要設計,有利於所應用發光或顯示裝置的最佳化。In summary, the nano-column array light-emitting diode and the single-nano column light-emitting diode provided by the embodiments of the present invention overcome the current luminescence by using thick, stress-free InGaN nano-disc illuminators of different conventional techniques. The development of diodes, especially white light-emitting diodes, is limited, for example, in "green-gloss energy gaps" and high drive currents. In addition, the fabrication of the light-emitting diode of the embodiment of the present invention does not require special nano-fabrication technology, and has the ability to be mass-produced on a semiconductor substrate. In addition, the number, thickness and structure of the InGaN nanodisks of the embodiments of the present invention can be designed as needed to facilitate optimization of the applied illumination or display device.
製作白光Making white light InGaN/GaNInGaN/GaN 奈米柱陣列發光二極體範例Nano column array light-emitting diode example
本實施例是利用前述的電漿輔助分子束磊晶方法(PAMBE),在一3吋、N型、電阻率0.001至0.005 Ωcm的矽(111)基板上,沿者六方烏采(wurtzite)結構的c軸成長垂直自我排列的N型GaN奈米柱陣列、InGaN奈米盤、P型GaN奈米柱陣列。其中,與成長三族–氮化物(group III–nitride)薄膜時所用的三族分子束與氮氣通量比相較之下,本實施例使用更高的氮氣比例(nitrogen-rich,高氮含量)。本實施例利用一購自DCA儀器公司,型號DCA-60的PAMBE系統,其裝設有一大的射頻氮氣電漿源。射頻功率設為500W、氮氣流量設為每分鐘3立方公分(3 sccm)。由即時的反射式高能量電子繞射(reflection high energy electron diffraction, RHEED)觀察到所成長的奈米柱為六方烏采單結晶結構,奈米柱沿著c軸方向成長。另外,奈米柱的in-plane(垂直面)結晶軸符合下列磊晶關係:<2 0>∥[ 10]Si; <1 00>∥[11 ]Si。在成長InGaN奈米碟之前,先在前述矽基板上,以770˚C、鎵分子束平衡壓(BEPGa)9×10-8torr的條件,成長摻雜有矽、厚度約1 μm的N型GaN奈米柱陣列於矽基板上。之後,再於N型GaN奈米柱上成長InGaN奈米碟。每個奈米碟的發光波長是由磊晶溫度(T)以及三族的分子束通量所決定。如圖1a的發光二極體,三種不同厚度奈米碟的磊晶溫度分別為T1的750˚C、T2的700˚C、T3的690˚C。另外,成長T1奈米碟的鎵分子束平衡壓為7.5×10−8torr、銦分子束平衡壓2.6 × 10−8torr、InGaN/GaN的厚度比大約為25 nm/25 nm;成長T2奈米碟的鎵分子束平衡壓為6.2×10−8 torr、銦分子束平衡壓3.3×10−8torr、InGaN/GaN的厚度比大約為10 nm/25 nm;成長T3奈米碟的鎵分子束平衡壓為5.7×10−8torr、銦分子束平衡壓3.7×10−8torr、InGaN/GaN的厚度比大約為15 nm/25 nm。如圖1a所示,其中奈米碟T1、T2、T3的厚度介於10至25 nm,而GaN阻擋層7的厚度固定在25 nm。之後,以690˚C的條件,成長摻雜有鎂、厚度約1 μm的P型GaN奈米柱陣列於奈米碟上,其中,在磊晶時,逐漸提高Ga/N的通量比,使側向磊晶形成P型GaN奈米柱,藉此形成「準連續(quasi-continuous)」的P型GaN薄膜。This embodiment utilizes the aforementioned plasma assisted molecular beam epitaxy method (PAMBE) on a 吋(111) substrate of a 3吋, N type, resistivity of 0.001 to 0.005 Ωcm, along the hexagonal wurtzite structure. The c-axis grows vertically and self-aligned N-type GaN nanocolumn arrays, InGaN nanodisks, and P-type GaN nanopillar arrays. Among them, compared with the three-group molecular beam and nitrogen flux ratio used in growing a group III-nitride film, this example uses a higher nitrogen ratio (nitrogen-rich, high nitrogen content). ). This embodiment utilizes a PAMBE system from DCA Instruments, Model DCA-60, which is equipped with a large RF nitrogen plasma source. The RF power was set to 500 W and the nitrogen flow rate was set to 3 cubic centimeters per minute (3 sccm). It is observed by the reflection high energy electron diffraction (RHEED) that the grown nano column is a hexagonal unilateral crystal structure, and the nano column grows along the c-axis direction. In addition, the in-plane (vertical plane) crystal axis of the nano-pillar conforms to the following epitaxial relationship: <2 0>∥[ 10] Si ; <1 00>∥[11 ] Si . Before growing the InGaN nanodisk, the N-doped substrate has a thickness of about 1 μm and a thickness of about 1 μm on the ruthenium substrate at 770 ̊C and gallium molecular beam equilibrium pressure (BEP Ga ) of 9×10 -8 torr. The GaN nanopillar array is arrayed on a ruthenium substrate. Thereafter, an InGaN nanodisk was grown on an N-type GaN nanocolumn. The wavelength of light emitted by each nanodisk is determined by the epitaxial temperature (T) and the molecular flux of the three groups. As shown in the light-emitting diode of Fig. 1a, the epitaxial temperatures of three different thickness nanodisks are 750 ̊C for T1, 700 ̊C for T2, and 690 ̊C for T3. In addition, the equilibrium molecular pressure of the gallium molecular beam of the grown T1 nanodisk is 7.5×10 −8 torr, the equilibrium voltage of the indium molecular beam is 2.6 × 10 −8 torr, and the thickness ratio of InGaN/GaN is about 25 nm/25 nm; The gallium molecular beam equilibrium pressure of the rice dish is 6.2×10 −8 torr, the indium molecular beam equilibrium pressure is 3.3×10 −8 torr, and the thickness ratio of InGaN/GaN is about 10 nm/25 nm; the gallium molecule of the grown T3 nanodisk The bundle equilibrium pressure is 5.7×10 −8 torr, the indium molecular beam equilibrium pressure is 3.7×10 −8 torr, and the thickness ratio of InGaN/GaN is approximately 15 nm/25 nm. As shown in FIG. 1a, wherein the thickness of the nano-discs T1, T2, T3 is between 10 and 25 nm, and the thickness of the GaN barrier layer 7 is fixed at 25 nm. Thereafter, a P-type GaN nanocolumn array doped with magnesium and having a thickness of about 1 μm is grown on a nanodisk at a temperature of 690 ̊C, wherein the flux ratio of Ga/N is gradually increased during epitaxy. A P-type GaN nanocolumn is formed by lateral epitaxy, thereby forming a "quasi-continuous" P-type GaN thin film.
為形成一發光二極體,本實施例先以感應式耦合電漿法(inductively coupled plasma, ICP)形成一260×280 μm2的平台,有效電流通過區域約為47,100 μm2。接著在上述平台上以二氧化矽為蝕刻遮罩,蝕刻形成一區域以在其上成長GaN奈米柱與奈米盤。接著,在10−7torr真空下,以蒸鍍方法形成分別與矽基板以及P型GaN奈米柱陣列歐姆接觸的鈦/金電極與鎳/金電極,厚度分別是60 nm/40 nm以及15 nm/35nm。鎳/金電極的厚度薄到足以使光線穿透。In order to form a light-emitting diode, the embodiment first forms a platform of 260×280 μm 2 by inductively coupled plasma (ICP), and the effective current passing region is about 47,100 μm 2 . Next, on the above platform, cerium oxide is used as an etch mask, and an area is formed by etching to grow a GaN nanocolumn and a nanodisk thereon. Next, under the vacuum of 10 −7 torr, the titanium/gold electrode and the nickel/gold electrode were respectively formed in ohmic contact with the tantalum substrate and the P-type GaN nanocol array, and the thicknesses were 60 nm/40 nm and 15 respectively. Nm/35nm. The thickness of the nickel/gold electrode is thin enough to allow light to penetrate.
所製備白光發光二極體的電流電壓曲線,是以Keithley 2400電源電錶在室溫下測量。而電激發光光譜與光激發螢光光譜(photoluminescence,PL)的測量,是以光學分光系統結合一探針量測系統(probing station)作為測量設備。在室溫下以10倍物鏡(Mitutoyo, 折射率NA = 0.28)放大,並結合裝設有液態氮冷卻之電荷耦合元件(CCD)感測晶片的光譜儀(HR460, Jobin-Yvon)量測電激發光光譜。該光譜儀以一NIST可追溯至美國國家標準與技術局之鎢鹵光源(Ocean Optics, HL-2000-CAL)進行校正。The current-voltage curves of the prepared white light-emitting diodes were measured at room temperature with a Keithley 2400 power meter. The measurement of electroluminescence spectrum and photoluminescence (PL) is based on an optical spectroscopic system combined with a probe measuring station as a measuring device. Amplify at room temperature with a 10x objective (Mitutoyo, refractive index NA = 0.28) and measure the electrical excitation with a spectrometer (HR460, Jobin-Yvon) equipped with a liquid nitrogen cooled charge coupled device (CCD) sensing wafer. Light spectrum. The spectrometer is calibrated with a NIST traceable tungsten halogen source (Ocean Optics, HL-2000-CAL) from the National Institute of Standards and Technology.
製作單根InGaN/GaN奈米柱發光二極體範例Making a single InGaN/GaN nanopillar LED sample
本實施例以前述PAMBE方法製作單根奈米柱發光二極體。首先,在3吋、N型矽(111)基板上,以770˚C的條件,成長摻雜有矽、厚度約1.2 μm的N型GaN奈米柱於矽基板上。之後,以705˚C、鎵分子束平衡壓為3.5×10−8torr、銦分子束平衡壓2.6×10−8torr的條件,於N型GaN奈米柱上成長40 nm厚的InGaN奈米碟。最後,再以685˚C的條件,成長厚度約800 nm的P型GaN奈米柱於InGaN奈米碟上方。In this embodiment, a single nano column light-emitting diode is fabricated by the aforementioned PAMBE method. First, an N-type GaN nano column doped with germanium and having a thickness of about 1.2 μm was grown on a germanium substrate on a 3 吋, N-type germanium (111) substrate under conditions of 770 ̊C. After that, 40 nm thick InGaN nm was grown on the N-type GaN nanocolumn with 705 ̊C, gallium molecular beam equilibrium pressure of 3.5×10 −8 torr, and indium molecular beam equilibrium pressure of 2.6×10 −8 torr. dish. Finally, a P-type GaN nanocolumn with a thickness of about 800 nm was grown over the InGaN nanodisk at 685 ̊C.
在PAMBE磊晶程序結束後,將所製備的單根奈米柱發光二極體浸沒於1wt%的氫氟酸水溶液30秒,以移除在奈米柱表面上的自生氧化層。接著,將單根奈米柱發光二極體以超音波床震洗模式,使之懸浮於異丙醇溶液,之後,將單根奈米柱發光二極體設置於一表面覆蓋有約500 nm氧化層的矽基板上。兩接觸電極的圖案(pattern)是以標準光學微影製程與掀離法(photolithography and lift off)製作。兩接觸電極皆為鈦/金,厚度皆為20 nm/35 nm;其製作方法是在腔體內壓力約10−7torr的範圍下,以電子束蒸鍍製作。在蒸鍍程序後,所製備的單根奈米柱發光二極體,在真空腔體壓力10−9torr的條件,以600˚C進行退火處理20秒。After the end of the PAMBE epitaxial process, the prepared single nanocolumn light-emitting diode was immersed in a 1 wt% aqueous solution of hydrofluoric acid for 30 seconds to remove the autogenous oxide layer on the surface of the nanocolumn. Next, a single nano column light-emitting diode is suspended in an isopropanol solution in an ultrasonic bed shock-washing mode, and then a single nano-column light-emitting diode is disposed on a surface covered with about 500 nm. The oxide layer is on the germanium substrate. The pattern of the two contact electrodes is made by standard photolithography and lift off. Both contact electrodes are made of titanium/gold and have a thickness of 20 nm/35 nm. The fabrication method is made by electron beam evaporation in the range of about 10 −7 torr in the chamber. After the evaporation process, the prepared single-nano column light-emitting diode was annealed at 600 ̊C for 20 seconds under vacuum chamber pressure of 10 −9 torr.
本領域熟悉技藝人士可根據本發明所揭露實施例,作各種修飾、替換或變更,其皆應屬於本發明的範圍。例如,雖然圖1a例示一種水平式發光二極體,但其也可以是其他種形式,例如垂直式發光二極體。其他基板也可能取代矽基板。接觸電極可以其他材質製成,具有其他結構或外觀,及/或形成於其他位置等。形成於矽基板上方的發光二極體結構,可被轉移至另一基板,例如金屬基板、塑膠基板、印刷電路板、透明基板,或因應各種需要的其他基板上。此外,本領域已知的技術方法,也許可被用來替換實施例製造方法中的一或多個步驟。P型基板或可取代N型基板,且P型與N型氮化鎵奈米柱陣列3/5的位置可互換。於本說明書,「氮化鎵(GaN)」與「氮化銦鎵(InGaN)」可意指「氮化鎵基(GaN-based)」與「氮化銦鎵基(InGaN-based)」;其成分可略為調整或改變。例如,以氮化鋁銦鎵(AlInGaN)取代氮化銦鎵(InGaN),以氮化鋁鎵(AlGaN)取代氮化鎵(GaN)。A person skilled in the art can make various modifications, substitutions or alterations in accordance with the embodiments of the present invention, which are within the scope of the invention. For example, although FIG. 1a illustrates a horizontal light emitting diode, it may be of other forms, such as a vertical light emitting diode. Other substrates may also replace the germanium substrate. The contact electrodes can be made of other materials, have other structures or appearances, and/or be formed at other locations. The light emitting diode structure formed over the germanium substrate can be transferred to another substrate such as a metal substrate, a plastic substrate, a printed circuit board, a transparent substrate, or other substrate in response to various needs. Moreover, technical methods known in the art may be used to replace one or more of the steps in the fabrication methods of the embodiments. The P-type substrate may be substituted for the N-type substrate, and the positions of the P-type and N-type gallium nitride nano-pillar arrays 3/5 may be interchanged. In this specification, "GaN" and "InGaN" may mean "GaN-based" and "InGaN-based"; Its composition may be slightly adjusted or changed. For example, indium gallium nitride (InGaN) is replaced by aluminum indium gallium nitride (AlInGaN), and gallium nitride (GaN) is replaced by aluminum gallium nitride (AlGaN).
圖5a顯示根據本發明另一實施例的垂直式發光二極體。如圖,垂直式發光二極體主要具有一基板1、一第一電極2、一第一型摻雜奈米柱陣列3、複數個主動發光區域4、一第二型摻雜奈米柱陣列5,以及一第二電極6。Figure 5a shows a vertical light emitting diode in accordance with another embodiment of the present invention. As shown in the figure, the vertical light emitting diode mainly has a substrate 1, a first electrode 2, a first type doped nano column array 3, a plurality of active light emitting regions 4, and a second type doped nano column array. 5, and a second electrode 6.
此為較佳地例示而非限制式例示,基板1是N型摻雜矽基板;第一電極2是一複合、多層結構電極,例如鈦/金(Ti/Au)電極;第一型摻雜奈米柱陣列3是N型氮化鎵奈米柱陣列;每個主動發光區域4包含一或多個氮化銦鎵奈米碟;第二型摻雜奈米柱陣列5是P型氮化鎵奈米柱陣列;第二電極6是一透明電極,例如氧化銦錫(indium tin oxide,ITO)電極。This is a preferred illustration, not a limitation, in which the substrate 1 is an N-type doped germanium substrate; the first electrode 2 is a composite, multilayer structure electrode such as a titanium/gold (Ti/Au) electrode; The nano-pillar array 3 is an N-type gallium nitride nano-pillar array; each active light-emitting region 4 includes one or more indium gallium nitride nanodisks; and the second-type doped nano-pillar array 5 is a P-type nitride The gallium nano-pillar array; the second electrode 6 is a transparent electrode such as an indium tin oxide (ITO) electrode.
在本較佳實施例,第一電極2與第一型摻雜奈米柱陣列3分別位於基板1的兩相對表面上。N型摻雜奈米柱陣列3由複數個N型奈米柱構成,並透過基板1與第一電極2歐姆接觸。一或多個氮化銦鎵(InGaN)奈米碟4位於每個N型氮化鎵奈米柱3上方。P型摻雜奈米柱陣列5由複數個P型奈米柱構成,且位於氮化銦鎵(InGaN)奈米碟4上方,其中一個P型氮化鎵奈米柱對應一個N型氮化鎵奈米柱。第二電極6,例如氧化銦錫電極6位於P型氮化鎵奈米柱陣列5上方並與之歐姆接觸。In the preferred embodiment, the first electrode 2 and the first type doped nano column array 3 are respectively located on opposite surfaces of the substrate 1. The N-type doped nano column array 3 is composed of a plurality of N-type nano columns and is in ohmic contact with the first electrode 2 through the substrate 1. One or more indium gallium nitride (InGaN) nanodiscs 4 are positioned above each of the N-type gallium nitride nanopillars 3. The P-type doped nano-pillar array 5 is composed of a plurality of P-type nano columns and is located above the indium gallium nitride (InGaN) nano-disc 4, wherein one P-type gallium nitride nano-pillar corresponds to an N-type nitride. Gallium nano column. A second electrode 6, such as an indium tin oxide electrode 6, is positioned over and in ohmic contact with the P-type gallium nitride nanocolumn array 5.
較佳地,第二電極6是經由圖案化(patterned)形成且由透明材質製成,或者因厚度足夠薄而具有所需透明度。每一P型奈米柱5及/或每一N型奈米柱3各具有兩端,其中靠近第二電極6的一端可較另一端寬,或者說具有較大橫截面積,如圖5b所示。此結構有助於避免漏電流。如有需要控制發光區域或為了其他目的,第一電極1也可被圖案化。注意本說明書中的「及/或」意指「及」或「或」。Preferably, the second electrode 6 is formed via patterning and made of a transparent material, or has a desired transparency because the thickness is sufficiently thin. Each of the P-type nanopillars 5 and/or each of the N-type nano-pillars 3 has two ends, wherein one end adjacent to the second electrode 6 may be wider than the other end, or has a larger cross-sectional area, as shown in FIG. 5b. Shown. This structure helps to avoid leakage currents. The first electrode 1 can also be patterned if necessary to control the illumination area or for other purposes. Note that "and/or" in this manual means "and" or "or".
如前所述,可經由控制奈米碟發光體的數量與發光波長,得到發光二極體所需的發光顏色,或者說發光波長。而每個奈米碟的發光波長,可由磊晶成長溫度T及/或成分間分子束通量比值,例如In/Ga的分子束通量比值決定。As described above, the illuminating color, or illuminating wavelength, required for the illuminating diode can be obtained by controlling the number of nano-disc illuminants and the illuminating wavelength. The wavelength of the light emitted by each nanodisk can be determined by the epitaxial growth temperature T and/or the molecular beam flux ratio between components, such as the molecular beam flux ratio of In/Ga.
如前述圖1c與圖3b,本發明發光二極體的發光顏色可涵蓋整個可見光譜。在圖5a與圖5b的實施例中,每個發光二極體包含三個T1氮化銦鎵(InGaN)奈米碟、一個T2氮化銦鎵奈米碟,以及一個T3氮化銦鎵奈米碟,且它們的磊晶成長溫度為T1>T2>T3。另外,在每兩個InGaN奈米碟4之間,設置一GaN阻擋層7。藉由上述結構,發光二極體可發出白光。As shown in Figures 1c and 3b above, the luminescent color of the light-emitting diode of the present invention can encompass the entire visible spectrum. In the embodiment of Figures 5a and 5b, each of the light-emitting diodes comprises three T1 indium gallium nitride (InGaN) nanodisks, one T2 indium gallium nitride nanodisk, and one T3 indium gallium nitride. Rice dishes, and their epitaxial growth temperature is T1>T2>T3. Further, between each two InGaN nanodisks 4, a GaN barrier layer 7 is provided. With the above structure, the light emitting diode can emit white light.
每個InGaN奈米碟的厚度可介於10 nm至25 nm(或40 nm)之間,但也可能大於或小於這個範圍。基板1的材質可選自下列群組其中之ㄧ:碳化矽(silicon carbide)、半導體、塑膠、金屬、玻璃,或前述材料的各種組合。此外,圖5a與圖5b的修飾、替換或變更至少與本文其他實施例所述相同。Each InGaN nanodisk may have a thickness between 10 nm and 25 nm (or 40 nm), but may also be larger or smaller than this range. The material of the substrate 1 may be selected from the group consisting of: silicon carbide, semiconductor, plastic, metal, glass, or various combinations of the foregoing. Moreover, the modifications, substitutions, or alterations of Figures 5a and 5b are at least as described in the other embodiments herein.
圖6a至圖6f顯示根據本發明另一實施例的製造方法,用於製造如圖5a或5b的發光二極體。Figures 6a through 6f show a fabrication method for fabricating a light-emitting diode as in Figure 5a or 5b, in accordance with another embodiment of the present invention.
參見圖6a,首先提供一基板1。基板1可包含,但不限於,矽基板、碳化矽基板、半導體基板,或其他導電材質所製基板。於本實施例,基板1為N型重摻雜矽基板(111),其電阻值約0.001 Ωm至0.005 Ωm。可以習知正常清潔程序清潔基板1。另外,可將基板1浸沒於一蝕刻緩衝液(buffered oxide etching solution,BOE)如氫氟酸(hydrofluoric acid,HF)或氟化銨(ammonium fluoride,NH4F)水溶液中,以移除基板1表面的自生氧化層。Referring to Figure 6a, a substrate 1 is first provided. The substrate 1 may include, but is not limited to, a germanium substrate, a tantalum carbide substrate, a semiconductor substrate, or a substrate made of other conductive materials. In the present embodiment, the substrate 1 is an N-type heavily doped germanium substrate (111) having a resistance value of about 0.001 Ωm to 0.005 Ωm. The substrate 1 can be cleaned by a normal cleaning procedure. In addition, the substrate 1 can be immersed in a buffered oxide etching solution (BOE) such as hydrofluoric acid (HF) or ammonium fluoride (NH 4 F) aqueous solution to remove the substrate 1 The surface of the autogenous oxide layer.
參見圖6b,接著,可利用蒸鍍(evaporation)的方法,例如熱蒸鍍(thermal evaporation)、電子束蒸鍍(electron-beam evaporation)、濺鍍(sputtering),或其他本領域已知的方法,形成一第一電極2,例如一鈦/金電極2於基板1的底面上。Referring to Figure 6b, an evaporation process, such as thermal evaporation, electron-beam evaporation, sputtering, or other methods known in the art, may be utilized. A first electrode 2, such as a titanium/gold electrode 2, is formed on the bottom surface of the substrate 1.
參見圖6c,接著,形成一電激發光(micro-electroluminescence,EL)結構於基板1的上表面。電激發光結構可包含一第一型摻雜奈米柱陣列3、複數個主動發光層區4,以及一第二型摻雜奈米柱陣列5;其形成方法是利用一磊晶程序,例如前述的電漿輔助分子束磊晶方法(PAMBE)。於本實施例,第一型摻雜奈米柱陣列3是N型氮化鎵奈米柱陣列;每個主動發光區域4包含一或多個氮化銦鎵(InGaN)奈米碟;第二型摻雜奈米柱陣列5是P型氮化鎵奈米柱陣列。Referring to FIG. 6c, a micro-electroluminescence (EL) structure is formed on the upper surface of the substrate 1. The electroluminescent structure may comprise a first type doped nano column array 3, a plurality of active light emitting layer regions 4, and a second type doped nano column array 5; the forming method is formed by using an epitaxial process, for example The aforementioned plasma assisted molecular beam epitaxy method (PAMBE). In this embodiment, the first type doped nano-pillar array 3 is an N-type gallium nitride nano-pillar array; each active light-emitting region 4 includes one or more indium gallium nitride (InGaN) nano-discs; The type doped nano column array 5 is a P-type gallium nitride nano column array.
以下例示一個可發白光的電激發光結構的製造方法。利用前述的電漿輔助分子束磊晶方法(PAMBE),在一3吋、N型、電阻率0.001至0.005 Ωcm的矽(111)基板上,沿著六方烏采(wurtzite)結構的c軸,成長垂直自我排列的N型GaN奈米柱陣列、InGaN奈米盤、P型GaN奈米柱陣列。其中,與成長三族–氮化物(group III–nitride)薄膜時所用的三族分子束與氮氣通量比相較之下,本實施例使用更高的氮氣比例(nitrogen-rich,高氮含量)。PAMBE系統裝設有一大的射頻氮氣電漿源。射頻功率設為500W、氮氣流量設為每分鐘3立方公分(3 sccm)。由即時的反射式高能量電子繞射(reflection high energy electron diffraction, RHEED)觀察到所成長的奈米柱為六方烏采單結晶結構,奈米柱沿著c軸方向成長。另外,奈米柱的in-plane(垂直面)結晶軸符合下列磊晶關係:<2 0>∥[ 10]Si; <1 00>∥[11 ]Si。在成長InGaN奈米碟之前,先在前述矽基板上,以770˚C、鎵分子束平衡壓(BEPGa)9×10-8torr的條件,成長摻雜有矽、厚度約1 μm的N型GaN奈米柱陣列於矽基板上。之後,再於N型GaN奈米柱上成長InGaN奈米碟。每個奈米碟的發光波長是由磊晶溫度(T)以及三族的分子束通量所決定。如圖5a與5b的發光二極體,三種不同厚度奈米碟的磊晶溫度分別為T1的750˚C、T2的700˚C、T3的690˚C。另外,成長T1奈米碟的鎵分子束平衡壓為7.5×10−8torr、銦分子束平衡壓2.6 × 10−8torr、InGaN/GaN的厚度比大約為25 nm/25 nm;成長T2奈米碟的鎵分子束平衡壓為6.2×10−8torr、銦分子束平衡壓3.3×10−8torr、InGaN/GaN的厚度比大約為10 nm/25 nm;成長T3奈米碟的鎵分子束平衡壓為5.7×10−8torr、銦分子束平衡壓3.7×10−8torr、InGaN/GaN的厚度比大約為15 nm/25 nm。如圖5a與圖5b所示,其中奈米碟T1、T2、T3的厚度介於10至25 nm,而GaN阻擋層7的厚度固定在25 nm。之後,以690˚C的條件,成長摻雜有鎂、厚度約1 μm的P型GaN奈米柱陣列於奈米碟上,如需要形成圖5b的結構,在磊晶時,逐漸提高Ga/N的通量比,使側向磊晶形成P型GaN奈米柱,藉此形成「準連續(quasi-continuous)」的P型GaN薄膜。A method of fabricating a white light-emitting electroluminescent structure is exemplified below. Using the aforementioned plasma assisted molecular beam epitaxy method (PAMBE), on a 吋(111) substrate of 3 吋, N type, resistivity 0.001 to 0.005 Ωcm, along the c-axis of the hexagonal wurtzite structure, An N-type GaN nanocolumn array, an InGaN nanodisk, and a P-type GaN nanocolumn array are grown vertically. Among them, compared with the three-group molecular beam and nitrogen flux ratio used in growing a group III-nitride film, this example uses a higher nitrogen ratio (nitrogen-rich, high nitrogen content). ). The PAMBE system is equipped with a large RF nitrogen plasma source. The RF power was set to 500 W and the nitrogen flow rate was set to 3 cubic centimeters per minute (3 sccm). It is observed by the reflection high energy electron diffraction (RHEED) that the grown nano column is a hexagonal unilateral crystal structure, and the nano column grows along the c-axis direction. In addition, the in-plane (vertical plane) crystal axis of the nano-pillar conforms to the following epitaxial relationship: <2 0>∥[ 10] Si ; <1 00>∥[11 ] Si . Before growing the InGaN nanodisk, the N-doped substrate has a thickness of about 1 μm and a thickness of about 1 μm on the ruthenium substrate at 770 ̊C and gallium molecular beam equilibrium pressure (BEP Ga ) of 9×10 -8 torr. The GaN nanopillar array is arrayed on a ruthenium substrate. Thereafter, an InGaN nanodisk was grown on an N-type GaN nanocolumn. The wavelength of light emitted by each nanodisk is determined by the epitaxial temperature (T) and the molecular flux of the three groups. As shown in the light-emitting diodes of Figures 5a and 5b, the epitaxial temperatures of three different thickness nanodisks are 750 ̊C for T1, 700 ̊C for T2, and 690 ̊C for T3. In addition, the equilibrium molecular pressure of the gallium molecular beam of the grown T1 nanodisk is 7.5×10 −8 torr, the equilibrium voltage of the indium molecular beam is 2.6 × 10 −8 torr, and the thickness ratio of InGaN/GaN is about 25 nm/25 nm; The gallium molecular beam equilibrium pressure of the rice dish is 6.2×10 −8 torr, the indium molecular beam equilibrium pressure is 3.3×10 −8 torr, and the thickness ratio of InGaN/GaN is about 10 nm/25 nm; the gallium molecule of the grown T3 nanodisk The bundle equilibrium pressure is 5.7×10 −8 torr, the indium molecular beam equilibrium pressure is 3.7×10 −8 torr, and the thickness ratio of InGaN/GaN is approximately 15 nm/25 nm. As shown in Fig. 5a and Fig. 5b, wherein the thickness of the nanodisks T1, T2, T3 is between 10 and 25 nm, and the thickness of the GaN barrier layer 7 is fixed at 25 nm. Thereafter, a P-type GaN nano-pillar array doped with magnesium and having a thickness of about 1 μm is grown on a nanodisk at a temperature of 690 ̊C. If it is necessary to form the structure of FIG. 5b, Ga/ is gradually increased during epitaxy. The flux ratio of N causes lateral epitaxy to form a P-type GaN nanocolumn, thereby forming a "quasi-continuous" P-type GaN thin film.
另外,如有需要,可利用旋塗玻璃法(spin on glass)使減少或消除奈米柱之間的間隙。此法所用材料可包含一液態介電材料(liquid dielectric material)或一氧化物基(oxide-based)材料。In addition, if necessary, spin on glass can be used to reduce or eliminate the gap between the columns. The material used in this method may comprise a liquid dielectric material or an oxide-based material.
參見圖6d,形成具有定義開口8a的光阻層8於第二型摻雜奈米柱陣列5上。此步驟可以習知方法形成,例如光微影製程(photolithography)或電子束微影製程完成。例如,可先塗佈一光阻層於第二型摻雜奈米柱陣列5上,接著以光源照射,使轉移一圖案至光阻層,以定義開口8a。請注意其他似光罩材料,例如陽極氧化鋁(anodic aluminum oxide)基板,也可取代前述的光阻層8。Referring to Fig. 6d, a photoresist layer 8 having a defined opening 8a is formed on the second type doped nanopillar array 5. This step can be formed by conventional methods, such as photolithography or electron beam lithography. For example, a photoresist layer may be applied to the second type doped nano-pillar array 5, and then irradiated with a light source to transfer a pattern to the photoresist layer to define the opening 8a. Please note that other reticle materials, such as an anodic aluminum oxide substrate, may also be substituted for the photoresist layer 8 described above.
參見圖6e,可利用前述的蒸鍍方法,在開口8a位置形成第二電極6於第二型摻雜奈米柱陣列5上。Referring to Fig. 6e, the second electrode 6 may be formed on the second type doped nano-pillar array 5 at the position of the opening 8a by the aforementioned evaporation method.
參見圖6f,如有需要,可形成另一光阻層(未圖示)或光罩層於第二電極6上方,再利用一適當方法,例如蝕刻法,較佳為感應式耦合電漿(inductively coupled plasma)蝕刻法,移除未使用的奈米柱陣列。為了節省成本,可省略此步驟。Referring to FIG. 6f, another photoresist layer (not shown) or a mask layer may be formed over the second electrode 6 if necessary, and then an appropriate method such as etching, preferably inductively coupled plasma is used. Inductively coupled plasma) etching to remove unused nanopillar arrays. To save costs, you can omit this step.
圖6a至圖6f實施例的各步驟順序也許可變更。例如,可先利用一光罩或光阻層定義電激發光結構3/4/5/7的成長區域,如此可省略圖6f的步驟。例如,可先形成電激發光結構3/4/5/7後,再形成第一電極2。The order of the steps of the embodiment of Figures 6a to 6f may be varied. For example, a reticle or photoresist layer can be used to define the growth region of the electroluminescent structure 3/4/5/7, so that the steps of Figure 6f can be omitted. For example, the first electrode 2 may be formed after the electroluminescence structure 3/4/5/7 is formed first.
本發明垂直式發光二極體的特性,相同於前述水平式發光二極體,故省略其描述。垂直式發光二極體的製程較為簡單,可節省成本。The characteristics of the vertical light-emitting diode of the present invention are the same as those of the above-described horizontal light-emitting diode, and the description thereof is omitted. The process of the vertical light-emitting diode is relatively simple and can save costs.
以上所述僅為本發明之較佳實施例而已,並非用以限定本發明之申請專利範圍;凡其他未脫離發明所揭示之精神下所完成之等效改變或修飾,均應包含在下述之申請專利範圍內。The above is only the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention; all other equivalent changes or modifications which are not departing from the spirit of the invention should be included in the following Within the scope of the patent application.
1...N型矽基板/基板1. . . N-type substrate/substrate
2...(鈦/金電極)/第一電極2. . . (titanium/gold electrode) / first electrode
3...N型GaN奈米柱陣列/N型GaN奈米柱/第一型摻雜奈米柱陣列3. . . N-type GaN nano column array / N type GaN nano column / first type doped nano column array
4...InGaN奈米碟/主動發光區域4. . . InGaN nanodisk / active light emitting area
5...P型GaN奈米柱陣列/P型GaN奈米柱/第二型摻雜奈米柱陣列5. . . P-type GaN nano column array / P type GaN nano column / second type doped nano column array
6...(鎳/金電極)/第二電極6. . . (nickel/gold electrode) / second electrode
7...GaN阻擋層7. . . GaN barrier layer
8...光阻層/光罩8. . . Photoresist layer / mask
8a...開口8a. . . Opening
T1-T3...(InGaN)奈米碟T1-T3. . . (InGaN) nano-disc
圖1a顯示根據本發明一實施例之白光發光二極體的立體圖;
圖1b顯示圖1a的發光二極體,被施加20 mA的驅動電流時發出白光的照片,而圖下方顯示在各種驅動電流時的電激發光(micro-electroluminescence,EL)之放大10倍的顯微照片;
圖1c顯示圖1a的發光二極體,被施加20 mA的驅動電流時之電激發光之放大100倍的顯微照片,該發光二極體可發出全波段的可見光;
圖1d顯示圖1a的發光二極體之國際照明委員會(CIE 1931)xy色度圖,其中驅動電流從5 mA到25 mA。
圖2a顯示根據本發明實施例的InGaN/GaN奈米柱陣列白光發光二極體,其驅動電流為1 mA至25 mA的電激發光圖譜。
圖2b顯示在圖2a之兩波峰(448、569 nm)與整體之驅動電流與電激發光強度的關係圖。
圖3a顯示根據本發明一實施例之單根InGaN/GaN奈米柱發光二極體的電流—電壓曲線。
圖3b顯示根據本發明一些實施例之單根InGaN/GaN奈米柱發光二極體的電激發光圖譜,其中每個發光二極體具有一InGaN奈米碟。
圖3c顯示圖3a的單根InGaN/GaN奈米柱發光二極體,當驅動電流由100 nA增加至500 nA時,發光主波長維持在475 nm。
圖4a顯示圖3a的單根InGaN/GaN奈米柱發光二極體,在驅動電流500 nA時的偏振(polarized)電激發光圖譜。
圖4b顯示圖3a的單根InGaN/GaN奈米柱發光二極體,利用極座標表示電激發光強度之二維空間分佈與奈米柱幾何的相對關係。
圖5a與圖5b顯示根據本發明兩實施例用於發白光的發光二極體示意圖。
圖6a至圖6f顯示根據本發明另一實施例用於製作如圖5a或圖5b發光二極體的方法。1a shows a perspective view of a white light emitting diode according to an embodiment of the invention;
Fig. 1b shows a photo of the light-emitting diode of Fig. 1a, which emits white light when a driving current of 20 mA is applied, and the micro-electroluminescence (EL) of the driving current is amplified 10 times. Microphotograph
Figure 1c shows a photomicrograph of the LED of Figure 1a, magnified 100 times the electrical excitation light when a driving current of 20 mA is applied, which emits full-band visible light;
Figure 1d shows the International Commission on Illumination (CIE 1931) xy chromaticity diagram of the light-emitting diode of Figure 1a with drive currents from 5 mA to 25 mA.
2a shows an InGaN/GaN nanopillar array white light emitting diode with an electric excitation spectrum of 1 mA to 25 mA, in accordance with an embodiment of the present invention.
Figure 2b shows the relationship between the two peaks (448, 569 nm) and the overall drive current and the intensity of the electrical excitation light in Figure 2a.
Figure 3a shows a current-voltage curve for a single InGaN/GaN nanopillar light emitting diode in accordance with an embodiment of the present invention.
Figure 3b shows an electroluminescent map of a single InGaN/GaN nanopillar light emitting diode in accordance with some embodiments of the invention, wherein each light emitting diode has an InGaN nanodisk.
Figure 3c shows the single InGaN/GaN nanopillar light-emitting diode of Figure 3a. When the drive current is increased from 100 nA to 500 nA, the dominant wavelength of illumination is maintained at 475 nm.
Figure 4a shows a polarized electroluminescent pattern of a single InGaN/GaN nanopillar light emitting diode of Figure 3a at a drive current of 500 nA.
Figure 4b shows the single InGaN/GaN nanopillar light-emitting diode of Figure 3a, using polar coordinates to indicate the relative relationship between the two-dimensional spatial distribution of the electrical excitation light intensity and the geometry of the nanocolumn.
Figures 5a and 5b show schematic views of a light-emitting diode for emitting white light in accordance with two embodiments of the present invention.
Figures 6a through 6f show a method for fabricating a light emitting diode as in Figure 5a or Figure 5b in accordance with another embodiment of the present invention.
1...N型矽基板/基板1. . . N-type substrate/substrate
2...(鈦/金電極)/第一電極2. . . (titanium/gold electrode) / first electrode
3...N型GaN奈米柱陣列/N型GaN奈米柱/第一型摻雜奈米柱陣列3. . . N-type GaN nano column array / N type GaN nano column / first type doped nano column array
4...InGaN奈米碟/主動發光區域4. . . InGaN nanodisk / active light emitting area
5...P型GaN奈米柱陣列/P型GaN奈米柱/第二型摻雜奈米柱陣列5. . . P-type GaN nano column array / P type GaN nano column / second type doped nano column array
6...(鎳/金電極)/第二電極6. . . (nickel/gold electrode) / second electrode
7...GaN阻擋層7. . . GaN barrier layer
T1-T3...(InGaN)奈米碟T1-T3. . . (InGaN) nano-disc
Claims (22)
一基板;
一第一電極,設置於該基板下方;
一N型氮化鎵奈米柱陣列,具有複數個N型氮化鎵奈米柱位於該基板上,且與該第一電極歐姆接觸;
一或多個氮化銦鎵奈米碟,設置於每個N型氮化鎵奈米柱上;
一P型氮化鎵奈米柱陣列,具有複數個P型氮化鎵奈米柱,其中每個該P型氮化鎵奈米柱對應一個該N型氮化鎵奈米柱,且被設置於每個所對應之N型氮化鎵奈米柱上方的該氮化銦鎵奈米碟的上方;以及
一第二電極,與該P型氮化鎵奈米柱陣列歐姆接觸;
藉此,每一該N型氮化鎵奈米柱與其對應的該一或多個氮化銦鎵奈米碟以及對應的該P型氮化鎵奈米柱構成一個別發光二極體,其可在未使用磷光劑條件下發出白光。A light emitting diode comprising:
a substrate;
a first electrode disposed under the substrate;
An N-type gallium nitride nano-pillar array having a plurality of N-type gallium nitride nano-pillars on the substrate and in ohmic contact with the first electrode;
One or more indium gallium nitride nanodisks are disposed on each of the N-type gallium nitride nano columns;
a P-type gallium nitride nano-pillar array having a plurality of P-type gallium nitride nano-pillars, wherein each of the P-type gallium nitride nano-pillars corresponds to one of the N-type gallium nitride nano-pillars, and is set Above the indium gallium nitride nanodisk above each corresponding N-type gallium nitride nanocolumn; and a second electrode in ohmic contact with the P-type gallium nitride nanocolumn array;
Thereby, each of the N-type gallium nitride nano-pillars and the corresponding one or more indium gallium nitride nano-discs and the corresponding P-type gallium nitride nano-pillars form a different light-emitting diode, White light can be emitted without the use of a phosphor.
提供一導電基板;
形成一第一電極於該基板下表面;
形成一N型氮化鎵奈米柱陣列於該基板上表面,該N型氮化鎵奈米柱陣列具有複數個N型氮化鎵奈米柱與該第一電極歐姆接觸;
形成一或多個氮化銦鎵奈米碟於每個N型氮化鎵奈米柱上;
形成一P型氮化鎵奈米柱陣列,其具有複數個P型氮化鎵奈米柱,其中每個P型氮化鎵奈米柱對應一個N型氮化鎵奈米柱,且被形成於每個所對應之N型氮化鎵奈米柱上方的該氮化銦鎵奈米碟的上方;以及
形成一第二電極,與該P型氮化鎵奈米柱陣列歐姆接觸;
其中透過控制該一或多個氮化銦鎵奈米碟的數量與厚度,該發光二極體可發出白光。A method for manufacturing a light-emitting diode, comprising:
Providing a conductive substrate;
Forming a first electrode on a lower surface of the substrate;
Forming an N-type gallium nitride nano-pillar array on the upper surface of the substrate, the N-type gallium nitride nano-pillar array having a plurality of N-type gallium nitride nano-pillars in ohmic contact with the first electrode;
Forming one or more indium gallium nitride nanodisks on each of the N-type gallium nitride nano columns;
Forming a P-type gallium nitride nano column array having a plurality of P-type gallium nitride nano columns, wherein each P-type gallium nitride nano column corresponds to an N-type gallium nitride nano column and is formed Above the indium gallium nitride nanodisk above each corresponding N-type gallium nitride nanocolumn; and forming a second electrode in ohmic contact with the P-type gallium nitride nanocolumn array;
The light emitting diode emits white light by controlling the number and thickness of the one or more indium gallium nitride nanodisks.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US13/335,199 US8669128B2 (en) | 2010-07-29 | 2011-12-22 | Method of producing III-nitride light-emitting diode |
Publications (2)
Publication Number | Publication Date |
---|---|
TW201327915A true TW201327915A (en) | 2013-07-01 |
TWI497764B TWI497764B (en) | 2015-08-21 |
Family
ID=49225246
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
TW101104230A TWI497764B (en) | 2011-12-22 | 2012-02-09 | Iii-nitride light-emitting diode and method of producing the same |
Country Status (1)
Country | Link |
---|---|
TW (1) | TWI497764B (en) |
-
2012
- 2012-02-09 TW TW101104230A patent/TWI497764B/en active
Also Published As
Publication number | Publication date |
---|---|
TWI497764B (en) | 2015-08-21 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
TWI541992B (en) | Light-emitting diode display and method of producing the same | |
TWI430473B (en) | Iii-nitride light-emitting diode and method of producing the same | |
US8835903B2 (en) | Light-emitting diode display and method of producing the same | |
Jia et al. | Recent progress in GaN‐based light‐emitting diodes | |
TWI300995B (en) | Light emitting diode of a nanorod array structure having a nitride-based multi quantum well | |
JP2009515340A (en) | Optical device featuring a textured semiconductor layer | |
JP2008277714A (en) | METHOD FOR MANUFACTURING GaN-BASED SEMICONDUCTOR LIGHT EMITTING DIODE | |
Kikuchi et al. | Growth and characterization of InGaN/GaN nanocolumn LED | |
US8669128B2 (en) | Method of producing III-nitride light-emitting diode | |
Velpula et al. | Full-Color III-Nitride Nanowire Light-Emitting Diodes. | |
CN106876544A (en) | A kind of spontaneous White-light LED chip structure of GaN base unstressed configuration powder and preparation method thereof | |
JP5115925B2 (en) | Microcrystalline nitride semiconductor optical / electronic devices with controlled crystal orientation and facets | |
KR20060121432A (en) | Rod type light emitting structure and method for forming the same | |
TWI497764B (en) | Iii-nitride light-emitting diode and method of producing the same | |
KR101644156B1 (en) | Light emitting device having active region of quantum well structure | |
KR20080030042A (en) | Light emitting diode of a nanorod array structure having a nitride-baseed multi quantum well | |
JP5240881B2 (en) | Microcrystalline nitride semiconductor optical / electronic devices with controlled crystal orientation and facets | |
Kim et al. | Enhanced light output power of GaN-based light emitting diodes with overcut sideholes formed by wet etching | |
RU2548610C2 (en) | WHITE GLOW LED AND LED HETEROSTRUCTURE BUILT AROUND SOLID-STATE SOLID GaPAsN SOLUTIONS OF GaP AND Si SUBSTRATES | |
US20230079101A1 (en) | Micrometer scale light-emitting diodes | |
Zhang et al. | Electroluminescence from ZnO nanorod/unetched GaN LED wafers under forward and reverse biases | |
TWI485880B (en) | Light-emitting diode chip and manufacturing method thereof | |
Lee et al. | Characterization of the InGaN/GaN multi-quantum-wells light-emitting diode grown on patterned sapphire substrate with wide electroluminescence spectrum | |
KR20150117744A (en) | manufacturing method of white LED using nanorod and white LED thereby | |
Willander et al. | Intrinsic white-light emission from zinc oxide nanorods heterojunctions on large-area substrates |