Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/47581
標題: Epitaxial Growth and Device Fabrication of ZnO-Based Optoelectronic Semiconductors
氧化鋅系列磊晶材料及光電元件之整合研究-總計畫
作者: 武東星
姬梁文
林得裕
林佳鋒
關鍵字: ZnO
氧化鋅
光電工程
MOCVD
Heterostructure
LED
UV Detector
Solid-State Lighting
有機金屬化學氣相磊晶
異質結構
發光二極體
UV 檢光器
固態照明
基礎研究
摘要: In the field of solid-state lighting, white light-emitting diode (LED) is one of the verypromising and globally perspective products. It has the strengths of small volume, non-heatradiation, low electricity expending, long life and better reaction speed rate….etc. Based on thetrend to energy-saving and environmental protection, most of the countries from the Europe,America and Japan have decided to choose white-light LEDs as the new illumination lighting in 21th century. Once the solid-state lighting replacing all the light sources in indoors and outdoors, thelighting power can be reduced to half of the current value. It is very worthy to study the foundationresearch and the application of solid-state lighting using LEDs.Currently the most popular white-light pumping sources are GaN, SiC and ZnO. Among them,the GaN and ZnO are belong to the direct band-gap semiconductors while SiC is the indirectband-gap semiconductor. Today GaN technology leads and widely uses to make white-light LEDs.The high luminous efficiency and low manufacture cost are two basic issues if one would realize allsolid-state lighting. ZnO constitutes an ideal material for these issues, mainly because excesselectrons and holes form tightly-bound excitons, which leads to very efficient near-band-gaprecombination at room temperature and even higher. Other advantages of ZnO as an emitter,especially with respect to its chief rival, GaN, are the availability of large-area ZnO substrates, thepossibility of low temperature epitaxial growth, and excellent radiation hardness. Previous studieshave pointed out that the efficiencies of white-light LEDs can exceed 100 lm/W using ZnO or AlNcompound materials combined the calcium phosphates. In the present stage, replacement of thelighting sources by any alternative products must reach this luminous efficiency (>100 lm/W).Intrinsic ZnO film is always an n-type semiconductor material. In order to obtain p-type ZnOfilm, it must be through doping process. P-type ZnO epilayer is hardly to achieve because there areintrinsic defects existing in the ZnO. Therefore the first problem at present is how to gethigh-quality p-type ZnO epilayer and fabricate the ZnO-based p-n junction structure. Accordingly,we have organized a research team, in which four professors who majors in material growth, opticalmeasurement and simulation, semiconductor process and optical device process respectively willdevote them in studying the key technology of ZnO-based LED. Therefore we have proposed a3-year integrated proposal named 」Epitaxial Growth and Device Fabrication of ZnO-basedOptoelectronic Semiconductor」.MOCVD method is very suitable for various semiconductor growths and with the high speeddegree grows up the good ZnO thin film. We will modify the Veeco D180 system and study the n and p-type ZnO epitaxial growth on various substrate materials (such as conductive ZnO, sapphireand SiC). In order to improve the luminescence efficiency at ZnO-based light emitting, the structuredesign of multiple-quantum-well (MQW) and the carrier conferment in MQW are the key points.Different MQW structure, including different well (CdZnO alloy) and barrier (MgZnO) materialscompositions, well width and doping conditions, will be investigated in this stage. The target of thisthree-year project is to develop an optimum UV-A (320-400 nm) white LED achieving aluminescence efficiency >100 lm/W. The UV-B (280-320 nm) photodetector will also be fabricatedto achieve a responsivity >0.3 A/W. The improvements in the optical and electrical properties areexpected to enhance the long-term reliability of the ZnO-based LED devices for future advancedsolid-state-lighting industry.
在光電照明這個領域中,白光發光二極體是十分被看好且受全球矚目的新興產品。因為它具有體積小、無熱輻射、耗電量低、壽命長和反應速度佳等優點,歐美和日本等國基於節約能源與環境保護的共識,皆決定選擇白光發光二極體作為二十一世紀照明的新光源,以國家的力量投入大量的資金與研究人力,積極開發具實用性的新光源。目前台灣所使用的能源大都仰賴進口,十分值得全力投入此一領域之基礎與應用研究。目前最常用來製作白光發光二極體激發光源的材料有氮化鎵(GaN)、碳化矽(SiC)、氧化鋅(ZnO)、其中GaN 與ZnO 是屬於直接能隙半導體材料,SiC 是屬於間接能隙半導體材料,因此GaN 是目前技術領先且最被廣泛應用於製作發光二極體之材料。高效率發光和低製造成本是實現固態照明的兩個關鍵問題,相較於氮化鎵它具有載子束縛能高、材料取得容易、生長溫度低、價格低廉、容易加工製程元件等優點,研究報告指出以ZnO 或AlN 材料開發出波長在254 nm 的UV-LED,並搭配磷酸鈣系螢化物質,其所發出的白光將可超過100 lm/W,要以白光發光二極體全面取代現階段照明光源,必須達到此一發光效率。本質的ZnO 塊材通常是一種n 型半導體材料,由於ZnO 材料中存在著較多的本質施體缺陷,對於摻雜產生高度自補償作用,難以實現p 型轉變,所以穩定的p 型ZnO 一直無法被成功的製作出來,因此限制了ZnO 光電元件的開發應用。因此目前首先需要解決的問題是,如何得到高品質p 型ZnO 磊晶薄膜的成長,以及ZnO p-n 結構等關鍵問題。有鑑於此,我們整合包含磊晶材料成長、光電元件製程、元件設計與光電量測等不同領域的四位教授來研發高效率氧化鋅二極體的關鍵技術,本研發計畫整合包括ZnO 材料之MOCVD 磊晶、發光二極體元件製程與結構設計、紫外光偵檢器等元件之研製,使得ZnO 相關材料能廣泛應用於固態照明、光電顯示、光電檢測等領域。並藉由四個子計畫研究團隊的三年投入,研製提高效率之雙異質與多重量子井結構之氧化鋅發光二極體,包含不同位能井(CdZnO alloy)與位障層(MgZnO)材料、寬度、?雜方式,對發光特性的影響,我們的目標是希望達到在UV-A (320-400 nm)波段之白光二極體效率大於100 lm/W,並開發UV B (280-320nm)波段的發光二極體,光偵檢器的暗電流(在5 伏特下驅動)小於1 nA,光響應值大於0.3A/W,期望整合四個子計畫之研發成果,改善ZnO 磊晶膜之光電特性,提高ZnO 光電元件之可靠度,為我國固態照明產業開闢新猷。
URI: http://hdl.handle.net/11455/47581
其他識別: NSC95-2221-E005-130-MY3
文章連結: http://grbsearch.stpi.narl.org.tw/GRB/result.jsp?id=1581149&plan_no=NSC95-2221-E005-130-MY3&plan_year=97&projkey=PB9706-0437&target=plan&highStr=*&check=0&pnchDesc=%E6%B0%A7%E5%8C%96%E9%8B%85%E7%B3%BB%E5%88%97%E7%A3%8A%E6%99%B6%E6%9D%90%E6%96%99%E5%8F%8A%E5%85%89%E9%9B%BB%E5%85%83%E4%BB%B6%E4%B9%8B%E6%95%B4%E5%90%88%E7%A0%94%E7%A9%B6-%E7%B8%BD%E8%A8%88%E7%95%AB
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