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Effects of Diamond-Like Carbon Multilayers on Characteristics of Thin-Film GaN LEDs
DLC;Thin film GaN;Electroplating;Laser lift-off
|Issue Date: ||2013-11-18 11:39:58 (UTC+8)|
|摘要: ||論文主要將高導熱之類鑽碳薄膜應用於薄膜型氮化鎵發光二極體(Thin-film GaN LED)，藉由精密電鍍技術(Electroplating)製作一具有金屬銅基板之薄膜氮化鎵發光二極體，搭配反射率達92 %之鎳/銀(Ni/Ag)鏡面及雷射剝離技術(Laser lift-off, LLO)，目的為製作一高亮度與高散熱特性之薄膜氮化鎵發光二極體。本論文導入類鑽碳膜層主要是降低元件之熱阻，進而使元件整體溫度降低。因此於大電流操作下，發光二極體具有良好的光輸出功率與電光轉換效率。|
電性方面，在小電流20 mA注入下，有類鑽碳膜與無類鑽碳膜之薄膜氮化鎵發光二極體其操作電壓分別為2.82 V與2.84 V；當大電流350 mA注入下，有類鑽碳膜與無類鑽碳膜之薄膜氮化鎵發光二極體其操作電壓分別為3.56 V與3.64 V。在-5 V操作電壓下，兩者的漏電流均小於1 µA之標準。光特性方面，在大電流700 mA注入下，有類鑽碳膜與無類鑽碳膜之薄膜氮化鎵發光二極體其光輸出功率分別為500.5 mW與487.7 mW；電光轉換效率分別為20.1 %與17.4 %。在熱特性方面，以紅外線熱影像分析晶片表面溫度，在大電流1400 mA注入下，分別為有類鑽碳膜146.86 ℃及無類鑽碳膜206.02 ℃；以暫態熱阻量測分析儀測得各元件之整體熱阻值為有類鑽碳膜21.3 K/W及無類鑽碳膜26.3 K/W。
In this study, a n-side up vertical-type thin-film GaN light emitting diodes (LEDs) with high thermal conductivity diamond-like carbon (DLC) film and Ni/Ag mirror have been fabricated by laser lift-off (LLO) and electroplating technique. This thesis introduces the DLC layer to reduce the junction temperature of LEDs, therefore decreasing the thermal resistance. Thus, the n-side up thin film LEDs presents good light power output and electro-optical conversion efficiency under high current operation.
In terms of electrical property, injecting a small current of 20 mA into the thin film GaN LEDs with and without DLC layer, the operating voltages were 2.82 V and 2.84 V, respectively. While injecting a higher current of 350 mA into the thin film GaN LEDs with and without DLC layer, the operating voltages were 3.56 V and 3.64 V, respectively. The leakage currents (@-5 V) of these devices were less than 1 µA. In terms of optical property, during the injection as high current as 700 mA, the output power of the thin film GaN LEDs with and without DLC film were 500.5 mW and 487.7 mW and the optical conversion efficiency were 20.1% and 17.4%, respectively. IR and T3ster system measurements can obtain the characteristic of thermal conductivity. In terms of thermal property, applying IR thermograph to analyze the surface temperature of the microchip. Under the injection as much higher current as 1400 mA, the surface temperature with and without DLC were 146.86 ℃ and 206.02 ℃, and the thermal resistances were 21.3 K/W and 26.3 K/W, respectively. From the above data, they suggest that the DLC can play a good thermal dissipation layer and effectively reduces the surface temperature of LEDs and thermal resistance.
|Appears in Collections:||[依資料類型分類] 碩博士論文|
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