改善氮化鎵發光二極體(GaN Light-Emitting Diode)的電流分佈，來得到高發光效率的元件一直是近來年研究的重要議題之一，在使用藍寶石基板(Sapphire)作為發光二極體元件的基板時，因為藍寶石基板並不導電，所以使得p型與n型電極必須位於同一面，使得電流從p型電極橫向流至n型電極時，容易產生電流擁擠效應。並且在p型電極下方主動區電子電洞複合所發出的光子，會因為位於其上方的p型電極為不透光的材質所以被遮蔽或者是反射後被半導體材料所吸收，因此造成光輸出功率的損失。
在實驗中製作並比較不同結構的元件，並量測發光二極體的I-V，L-I曲線，在結構上為了改善電流擁擠效應設計了不同的光罩圖形，使得p型到n型電極的電流，流經的路徑長度一致，來增加電流的均勻性，並且使用ITO(Indium tin oxide)做為透明導電層，而為了要使流經電極下方的電流能夠被有效的利用，在電極下方鍍製二氧化矽做為電流阻擋層來改善電極下方的光被遮蔽或者吸收的問題。
使用新設計的電極在有ITO的情況下輸出光功率提升了兩倍(ITO與p型電極面積比為6.84倍)，而加上電流阻擋層後在相同操作電流下，發光二極體輸出光功率提升了7.5%( p型電極與高台面積比為0.11倍)。

Improving non-uniform current spreading of GaN light emitting diodes (LED) to obtain high light-output efficiency is one of the most important issues in the LED industry. Because sapphire is an insulating substrate, both the p-type and n-type contacts are usually located on the same side of the chip. As a result, the current flows laterally according to the voltage and resistance distribution and tends to crowd around electrodes if no special design is made. In addition, the light generated in the active region beneath the opaque p-pad metal contact is blocked. It reduces the extraction efficiency of the LED.
In this research, we made various devices of different processes and structures. The resulted LED’s I-V and L-I curves were measured and compared. We designed a new mask pattern and developed ITO process to obtain a uniform current spreading, and used silicon dioxide as a current-blocking layer(CBL) under the p-pad to increase the light-output power.
The resulted L–I curves exhibit two times increase in the output power for LED with ITO layer and 7.5% increase for LED with CBL structure over the conventional diodes at the same bias current, while the associated area ratios in the mask design are 6.84(ITO/p-pad) and 0.11(p-pad/mesa), respectively.

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