具氧化侷限結構之微米尺寸發光二極體之研究

Abstract

由於氮化鎵材料的發光元件地廣泛應用，像是智慧型眼鏡、微投影機、智慧手錶、電視等領域，因此過去幾十年來氮化鎵相關的材料吸引了學術界和業界的目光。雖然照明效率已經可以達到超過300流明/瓦，但在高電流密度下及高溫下所造成的效率下降(efficiency droop)的問題還是令人沮喪。 我們提出一種具有良好的電流侷限的結構，本論文旨在探討效率下降(efficiency droop)現象與製作具氧化侷限結構之微米尺寸發光二極體，在完成之後，我們以連續波的方式對元件的光電特性進行量測，包括 LIV特性及近場的實驗結果，不同孔徑大小的InGaN/GaN based μLEDs被製作出來，5μm孔徑的元件可以達到高達101 kA/cm2的電流密度操作，我們進一步使用S-model去進行droop現象對不同孔徑大小的元件進行分析與討論。

在分析中，結果顯示出在micron scale下製作的μLEDs有比較好的電流擴散與比較小的temperture droop。而且最大電流操作密度隨著孔徑變小而提高，相信此結果對於GaN-based的光電元件發展上會有進一步的貢獻，例如垂直共振腔面射型雷射與 μLED array在顯示器上面的應用。

Due to the widespread applications of GaN-based material, such as smart glass, pico projector, smart watch, TV etc., the GaN-based material has attracted much attention of academia and industry. Although the luminous efficiency has been achieved higher than 300 lm/W, the efficiency droops appear disappointedly in excellent light emitting diodes under high injection level or at high temperature. We have designed a kind of structure which shows great current confinement. The thesis is focus on the droop phenomenon and fabrication of oxide confined micro scale light emitting diodes. The diode performance such as L-I-V curve, near field images are also shown in this thesis. Different size InGaN/GaN based micro-LEDs (μLEDs) are fabricated. An extremely high injection level above 101 kA/cm2 is achieved for 5 μm-diameter LED.And we further use S-model to anylysis droop phenomenon with different aperture size. In the analysis, result exhibited the distinct performances of tens micron μLEDs are attributed to uniformcurrent spreading and low junction temperature.However, the maximum endured current density still increases as the size of μLEDs reducing . It might be a tremendous contribution to the development of GaN-based optoelectronics,such as VCSEL and μLED array in display application.