新穎高亮度發光二極體結構成長與製作(II)

Abstract

節能減碳是目前全球矚目的議題，綠色產品方興未艾。白光發光二極體由於具有節 省能源、環保、高壽命與堅固耐用等優點，因此目前中、美、日、韓歐洲等國家均透 過國家型計畫，投入大量資金及人員全力積極發展相關技術與應用。自從高品質的氮 化鎵(GaN) 被Shuji Nakamura 成功的以有機金屬化學氣相沈積法(MOCVD) 成長之 後，引起學界及業界極大的興趣並投入大量的研發。三族-氮化物系列及其合金材料為 直接能隙，而且光譜涵蓋由紅外光到紫外光的範圍(Eg,InN = 0.7 eV， Eg,GaN = 3.4 eV，Eg,AlN = 6.2 eV)，對各種光電領域的應用，如發光二極體(LED) 或是太陽能電 池(solar cell) 等有著極大的潛力。白光發光二極體在固態照明的應用上尚未完全普 及，最主要的因素有下列幾點：(1)售價太高、(2)效率太低、(3)散熱問題及(4)標準化及 穩定度問題。價格與效率息息相關，有鑑於此，我們將於兩年計畫中提出可以提升內 部量子效益及外部量子效益的方法。內部量子效益將透過量子井/位能障結構設計及採 用無極性材料來達成，外部量子效益將透過奈米柱緩衝層及倒金字塔結構來達成，預計 可藉此提升70%~80%的外部量子效益，及達到60%~70%內部量子效益。

For a more energy-efficient and CO2-reducing era, the eye-catching "Green Products" are coming and still-growing. Eco-friendly white-light LED has shown great promise and benefits for energy-saving, improved durability. The LED-related techniques and applications are fully supported by the countries around the world including China, the United States, Japan, Korea and European Union. Starting with the major breakthroughs in GaN-based materials and devices of Shuji Nakamura et al., more groups worldwide join this new facet of nitride semiconductor research. Today, white modules are not available to all. To be commercialized, some pressing problems hindering further advances in solid state lighting includes: (1) high cost, (2) low quantum efficiency, (3) poor heat dissipation of sapphire substrate and (4) non-standardized process. We will propose the ways for increasing internal quantum efficiency (IQE) and external quantum efficiency (EQE). in this proposal by using novel barrier/well structures, non-polar material, nano-rod and micro pyramid structures. We estimated that it may promote the external quantum efficiency about 70%~80%, and achieves internal quantum efficiency about 60%~70%.