GaN基藍光發光二極體(Light Emittering Diode, LED)自1990 年代中期由日本日亞化公司的中村修二研究員開發成功後，即成為一熱門研究題材，LED具有體積小、壽命長、操作反應速度快、省電、可靠度高、不易破損、應用範圍廣且無熱輻射與水銀有毒物質污染等優點，其與螢光粉或利用RGB三原色LED組合形成之白色光源，於未來照明市場上極富應用潛力。此一 ”新世代光源”若要取代日光燈管，首先要面對的問題主要在於製作大面積、高效率藍光LED元件與解決傳統藍寶石(Sapphire)基板不導電、導熱不佳缺點等方面。本論文以雷射剝離技術(Laser Lift-off)置換藍寶石基板，選擇性電鍍銅鎳合金之金屬基板，三種不同底部反射鏡的設計製作45 mil大面積、高亮度垂直結構LED，以解決傳統GAN LED元件，散熱不佳、電流分佈不均、發光不均等諸多方面的問題，期望可對新世代LED光源之開發提供助益。

本論文採用選擇性電鍍銅鎳合金技術並使用248 nm 的KrF 準分子雷射，可完整反應解離 2 吋直徑藍寶石基板，成功地將在藍寶石基板上有機金屬化學氣相沈積系統(Metal Organic Chemical　Vapor Deposition, MOCVD)所沈積之GaN 磊晶薄膜置換至電鍍銅鎳基板上，且採用選擇性電鍍，可以直接使用雷射成功的將元件分離，以便後續封裝製程，電特性量測結果顯示，磊晶主動層(Active layer)並未因準分子雷射的照射而造成元件特性破壞，本研究所研製之垂直結構金屬基板LED 之光電特性遠勝於傳統水平結構藍寶石基板元件。實驗結果顯示，於350 mA 工作電流條件下，45 mil Vertical LED 工作電壓相似傳統水平式，光輸出功率甚至可比傳統者增加97%，且元件封裝後的power比傳統水平式LED高出13%。本研究結果顯示使用金屬基板所製得垂直式元件之光電特性遠較傳統橫向結構LED 優異，不僅可降低能源的耗損，於大電流、高功率之工作條件下，其可靠度也將大幅提升。

In the mid-1990s, nitride-based material was first successfully grown on sapphire by Shuji Nakamura of Nichia co. using Metal Organic Chemical vapor deposition (MOCVD) technology. Up to now, lots efforts have been made in the promotion of light extraction and efficiency of blue GaN-based LEDs. Owing to its advantageous of small volume, long life, fast responding time, low power consumption, lasting, better quality of reliability, smaller flexible lighting fixtures, intrinsically safety, and no mercury added, a novel solid-state white lighting source, so called " new generation lighting source " has been proposed using blue GaN-based LEDs and yellow phosphor powder or direct combination of lights emitting from RGB color LEDs.

However, challenging issues of GaN-based LEDs including poor light conversion efficiency and poor thermal conducting caused by the sapphire substrate, and non-scalable light output with respect to the chip size, etc., are still open questions.

This thesis aims to tackle the challenging issues of present GaN-based LEDs. Various methods including replacing the sapphire substrate with an electroplating substrate by laser lift-off technology, designing three kinds of bottom reflectors for vertical LED, the fabricating of 40 mil-high power vertical-structured metallic GaN-based LEDs were proposed. According to the material analysis and optoelectronic characterizations, the measured optoelectronic performances of vertical LED reveal a great improvement as compared to that of conventional lateral-structured LEDs.

As compared to regular-LEDs under an injection current of 350 mA, the working Voltage is similar to conventional LED, and the increase in light EL intensity is about 97% have been obtained. It is expected that the use of LLO in conjunction with Cu/Ni substrate and the improvement of bottom reflector would make possible the fabrication of vertical LED with even larger area, higher power and better efficiency.

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