量子侷限史塔克效應(quantum confined-Stark effect, QCSE)，會使得LED的發光效率下降。在本論文，為了減少多重量子井內的殘餘應力，我們製作了三種不同的應力釋放結構之發光二極體。利用電致發光(electroluminescence, EL)來測量其發光波長來判別其應力之大小。發光波長的藍移與其量子侷限史塔克效應是有相關的，樣本 A(應力釋放層結構為n型氮化鎵/未參雜氮化銦鎵 短周期超晶格)， 樣本 B (應力釋放層結構為,低溫成長 n型氮化鎵) 以及樣本 C (應力釋放層結構為P型氮化鎵/P型氮化銦鎵 短周期超晶格)屏蔽效應之藍移量分別為 0.39 奈米,0.32奈米以及0.54 奈米。LED B之外部量子效率是三者中最大的，在注入電流 20毫安培之下，其值為10.3 毫瓦。然而，樣本B之插座效率下滑(wall plug efficiency droop)因其較高的接面溫度表現最差。並且我們可以發現接面溫度是由其串聯電阻所主導，而其較高的串聯阻值則是與設計之應力釋放層有關。

Quantum confine Stark effect (QCSE) would reduce the efficiency of LEDs. To reduce the residual strain in the MQWs of LEDs, we fabricate three different strain-released LEDs. We use the electroluminescence (EL) to measure the emission wavelength and determine the strain of LEDs. It is well known that the QCSE is relative to the blueshift of emission wavelength. The blueshift of screening effect for LED A (Strain-released layer, n-GaN/u-InGaN SPS), LED B (Strain-released layer, LT n-GaN) and LED C (Strain-released layer, p-GaN/p-InGaN SPS) are 0.39 nm, 0.32 nm and 0.54 nm, respectively. External quantum efficiency of LED B is the largest, 10.3 mw with injection current 20 mA. However, the wall plug efficiency (WPE) droop of LED B is the smallest, which is attributed to its high junction temperature. Thus, the factor dominates in junction temperature is series resistance. Furthermore, the high series resistance would be attributed to the strain-released structure of LEDs.

chapter1
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