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標題: 具金屬基板氮化鎵發光二極體之研製
Fabrication of Metal-Substrate GaN-Based Light-Emitting Diodes
作者: 林文禹
Lin, Wen-Yu
關鍵字: GaN;氮化鎵;light-emitting diode (LED;laser lift-off;precision electroplating;發光二極體;雷射剝離技術;精密電鍍技術
出版社: 材料工程學研究所
本論文主要在研製垂直導通型氮化鎵藍光發光二極體,並探討此元件之特性。我們使用雷射剝離技術來剝離氮化鎵磊晶片的藍寶石基板,搭配精密電鍍技術,將剝離下來的氮化鎵薄膜轉移到金屬銅基板上,製作p型在下的氮化鎵/鏡面/銅結構發光二極體元件。將這種大面積垂直導通型之氮化鎵/鏡面/銅的發光二極體與傳統氮化鎵/藍寶石基板結構比較起來,其在20 mA之正向電壓分別為2.87及2.76 V,而在350 mA則分別為4.5及4.4 V,顯示出其操作電壓相差不大,意味串聯電阻並不會因為垂直導通的元件設計而變大。至於其在‐5 V反向偏壓時之漏電流則分別為33.8及77.6 nA,這顯示出藉由這樣的製程設計之可行性。另外,在20 mA時氮化鎵/鏡面/銅顯示比氮化鎵/藍寶石基板發光二極體高出2.7倍的發光強度,而輸出功率也隨著注入的電流至500 mA仍持續線性增加,並高於傳統結構有2倍之多,其中,傳統的氮化鎵/藍寶石基板結構發光二極體呈現先達到飽和的狀態,在並經由不同電流注入之激發光譜圖,得到大面積垂直導通型氮化鎵/鏡面/銅基板結構的發光二極體於大電流操作下,仍維持波長持續藍移之現象,顯示其在大電流操作下的穩定性,這也顯示經由置換銅基板結構後的氮化鎵發光二極體將有較佳的散熱效應,此即歸因於銅基板有良好的熱傳導係數。

A vertical conducting GaN/mirror/Cu LED fabricated using the laser lift-off and electroplating techniques is demonstrated. The selective p-GaN top area was first electroplated by a thick copper film, and then a UV laser was employed to separate the GaN thin film from the sapphire substrate. The forward voltages (@ 20 mA) of the original GaN/sapphire and p-side-down GaN/mirror/Cu LED samples were 2.76 and 2.87 V, respectively. These results indicated that the series resistance of the GaN/mirror/Cu LEDs does not arise greatly with the present vertical conducting structure. The leakage currents (@ -5 V) of the original GaN/sapphire and p-side-down GaN/mirror/Cu LED samples were 77.6 and 33.8 nA, respectively. This suggests that the present device structure will not result in additional leakage current in the GaN/mirror/Cu LED device. The luminance intensity of the vertical conducting p-side-down GaN/mirror/Cu LED presented about 2.7 times in magnitude as compared with that of the original GaN/sapphire LED (@ 20 mA). The light output power for the GaN/mirror/Cu LED was about twofold stronger (@ 500 mA). A more stable peak wavelength shift under high current injection was also observed. These results indicated that large-area copper substrate LEDs have better thermal management and good heat sink.
Appears in Collections:材料科學與工程學系

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