Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/4248
標題: 電極設計與電流分佈模擬之研究
Design of contact pattern and Simulation of current spreading for GaN-based light-emitting diodes
作者: 謝仲明
Xie, Chong-Ming
關鍵字: GaN
氮化鎵
current spreading
contact pattern
ITO
電流分佈
電極設計
透明導電層
出版社: 精密工程學系所
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摘要: 為提升氮化鎵型發光二極體(GaN-base of Light Emitting Diodes; LEDs)之發光效率與光輸出功率,目前相關研發方向主要朝著低操作電壓與高功率發展,但在高電流注入下產生熱衰竭與光電轉換效率不佳的問題,這時候電流分佈就顯得重要。傳統式的水平式結構電流為橫向傳輸,故其電流擁擠的效應較嚴重,且 p型氮化鎵無法高濃度摻雜,使導電率不佳,電流分佈未達理想,可藉由設計合適之電極圖型與沉積透明導電層於氮化鎵磊晶層表面,將有效的改善電流分佈,目前TCL主要使用氧化銦鎵(ITO)。本論文針對尺寸為10 mil×23 mil之水平結構LEDs其表面電極,設計三種新電極圖型(n電極圍繞35、65、100 %),進行特性模擬與元件製作,並模擬ITO之厚度與片電阻參數,研究電極圖案設計與ITO參數對LEDs之電流分佈與光電特性之影響。 製作傳統電極與新式電極之LEDs特性比較:電性方面,在小電流20 mA注入下,傳統電極設計、n電極圍繞35、65、100 %操作電壓為3.15 V、3.1 V、3.07 V與3.03 V;在-5 V操作電壓下,四者的漏電流均小於1 uA之標準。光特性方面,在150 mA注入下,傳統電極設計、n電極圍繞35、65、100 %之光輸出功率分別為34.0 mW、35.1 mW、34.2 mW與30.5 mW。在熱特性方面,在150 mA注入下,以紅外線熱影像分析傳統電極設計、n電極圍繞35、65、100 %之表面平均溫度分別為63 oC、53 oC、52 oC與45 oC。ITO參數之LEDs特性模擬:ITO厚度在200 nm之特性為相對極大值;ITO之片電阻為越低則特性越佳。
Recently, there are increasing interests in improving the light efficiency and output power of GaN-based light emitting diodes (LEDs), but thermal effect and poor power efficiency are followed at high injection current. At present, improving the current spreading to obtain low driving voltage and high light output power is an important topic for LEDs. Typically, the current spreading is lateral transmission for conventional LEDs, and it exhibits a serious current crowding effect. Under the circumstances, the deposition of a transparent conducting layer (TCL) for Indium Tin Oxide (ITO) and the electrodes with a well-designed pattern are very necessary, especially for improving current spreading. In this study, we have designed new contact patterns (35 %, 65 %, and 100 % n-pad surrounding design) to simulate and fabricate the chip (10 mil 23 mil) on surface of conventional LEDs. The effects of ITO thickness, sheet resistance, and the electrode pattern design on the current spreading and optical-electrical characteristics for LEDs were investigated. The forward voltages (@20 mA) of the contact pattern in conventional design for LEDs and contact patterns in new design 35 %, 65 %, and 100 % n-pad surrounding design LEDs were 3.15 V, 3.10 V, 3.07 V and 3.03 V, respectively. The leakage currents (@-5 V) of these devices were smaller than 1 uA. The output powers (@150 mA) of the contact pattern in conventional design for LEDs and contact patterns in new design 35 %, 65 %, and 100 % n-pad surrounding design LEDs were 34 mW, 35.1 mW, 34.2 mW and 30.5 mW, respectively. The surface temperatures (@150 mA) for the contact pattern in conventional design for LEDs and contact patterns in new design 35 %, 65 %, and 100 % n-pad surrounding design LEDs were 63 oC, 53 oC, 52 oC and 45 oC, respectively. From the simulation of ITO parameters for LEDs, we found that there was a relative maximum value as the thickness of ITO was 200 nm. The LEDs characteristics were improved with the decreasing of sheet resistance.
URI: http://hdl.handle.net/11455/4248
其他識別: U0005-1102201115421500
文章連結: http://www.airitilibrary.com/Publication/alDetailedMesh1?DocID=U0005-1102201115421500
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