本論文研究中，針對用於短距離光綠波段(520nm)光纖通訊之高速發光二極體做研究及製作。我們採用阻障層有(barrier)矽(Si)掺雜及無摻雜矽之氮化鎵氮化銦鎵多重量子井(MQW)試片來製作元件，由量測結果發現，阻障層具有矽摻雜之試片製作出來的光、電特性都有明顯的增加。(1)光特性方面，在相同電流操作之下(100mA)阻障層具有矽摻雜比沒有矽摻雜之光輸出功率大了兩倍(150μW vs. 75μW)，且光飽和功率也大了三倍(250μW vs. 80μW)，(2)電特性方面，在相同電流操作之下(100mA)阻障層具有矽摻雜比沒有矽摻雜之試片調制速度快了三倍(125MHz vs. 45MHz)。我們把原因歸納為使用阻障層具有掺矽雜試片可(1)減少載子遮蔽效應、(2)增加載子侷限效應、(3) 改善材料特性。另ㄧ方面，我們將試片最上層的P-GaN蝕刻掉來達成電流侷限的結構，由量測結果發現，電流侷限確實可以達到增加調制速度(170 MHz)，離應用在IEEE-1394 250Mbit/s的通訊傳輸協定上已經不遠了。但相反的，因為電流侷限結構使得電流集中注入在P型金屬下方的主動區，因此發光區域面積等效上就變得很小使得輸出光功率不如我們所預期，這是未來需改進的地方。 We demonstrate a high-speed GaN based Light-Emitting-Diode (LED) at a wavelength of around 520nm for the application to plastic optical fiber (POF) communication. By use of the n-type doping in the GaN barrier layers of the InxGa1-xN/GaN based multiple-quantum-well (MQW), superior performance of modulation-speed (120MHz vs. 40MHz) and output-power to the undoped control under the same bias current has been observed. According to the measured electrical-to-optical (E-O) bandwidths and extracted RC-limited bandwidths of both devices, the superior speed performance can be attributed to (1) Higher electron/hole radiative recombination rate in the n-doped MQW than that of undoped MQW. (2) Higher carrier-screening effect (3) improve InxGa1-xN/GaN based multiple-quantum-well (MQW)material quality. On the other hand, we demonstrated high speed GaN LED with current-confined structure which results of modulation-speed has about 160MHz. The current-confined structure can shorten carrier recombination time efficiently, but the output light intensity was decrease seriously. In the future, we will optimize the current-confined area and light emitting area to achieve high speed and high output power LED for IEEE-1394 250 Mbit/s POF applications.
