在本論文中，我們利用光學鍍膜的方式來改善藍光發光二極體的發光強度，又分成在發光二極體的正面及背面兩方面作討論，在元件正面是以蒸鍍的方式鍍上一層抗反射層，而在背面是鍍上反射鏡，以達到我們增加發光二極體發光強度的目的。 在發光二極體的正面，由於氮化鎵的折射率(約2.4)和空氣的折射率(1)差異相差很大，所以光經過折射率差異大的介質時，光穿透的比例將會減少，因此我們用二氧化矽、氮化矽、三氧化二鋁等材料作保護及抗氧化，並根據理論上薄膜干涉的計算及模擬，找出建設性干涉的膜厚，以提昇發光二極體的發光強度，並對沒有鍍抗反射層的發光二極體作光強度上的比較。 在發光二極體的背面，為了避免有光從元件的背面耗損，因此鍍上金、銀、鋁作背面金屬反射鏡，以及用二氧化矽及二氧化鈦折射率的差異，鍍成多層膜的高反射鏡(經理論計算反射率可高達99%以上)，並對鍍上金屬膜、多層膜的高反射鏡及一般製程的發光二極體作光強度及輸出功率的比較。 In this dissertation, we try to improve light extraction of blue/green light emitting diodes (LEDs) by means of optical coatings. For the purpose of extracting light inside LEDs, we focus on two topics, topside of LEDs with antireflective layers and bottom side of LEDs with reflectors. On topside of LEDs, the difference of refractive index between GaN (about 2.4) and air (1) is large, so the percentage of transmission is lowered. SiO2, Al2O3, SiNX is coated on the topside of InxGa1-xN/GaN LEDs as passivation and/or antireflective layer. According to the theory of interference, it can be suggest that the thickness of thin film with constructive interference will achieve the purpose of improving emissive intensity. And the intensity of LEDs coated with passivation and/or antireflective layer compared with that of non-coated LEDs will be discussed. For the purpose of preventing optical absorption at interface between the backside of LED and lead frame, the bottom side of substrate is coated with Au, Ag, Al, respectively, as metal reflectors. In addition, periodic stacked multiple layers of TiO2 and SiO2 are used as high reflector (above 99% form theoretical calculation) due to the large difference of refractive index between them. The comparison of luminous intensity (output power) between LEDs coated with metal or dielectric reflectors and non-coated LEDs will be discussed in this article.
