雖然目前大多數微型發光二極體顯示器，使用藍綠光微型發光二極體搭配量子點螢光粉生成紅色，但使用紅光能過達到更廣的色域、更高的穩定性、獨立控制以及感應器的需求。在本論文中，我們透過側壁處理的製程方法，以提升微型發光二極體的特性。採用多種側壁處理方法，結合不同沉積技術的機台，以及多樣的材料以提高側壁的反射率。透過各種量測機台，電致發光和積分球上的相關光電性(光輸出功率、外部量子效率、光電轉換效率)，評估微型發光二極體的特性。
由於微型發光二極體尺寸極小，受感應耦合電漿蝕刻後，側壁損傷對性能產生顯著影響。因此在此論文中提出側壁處理的重要性。對紅光磷化鋁鎵銦的微型發光二極體，我們提出使用不同秒數的檸檬酸(0、30、60、90、120 秒)進行側壁處理。結果顯示，經過60秒檸檬酸處理後，微型發光二極體的光輸出功率提升了31.08%，外部量子效率提升了5.4%。在前述研究基礎上，我們進一步提出側壁處理後立即進行側壁鈍化的方法。透過檸檬酸浸泡後，再浸泡硫化銨1小時以達到鈍化效果。鈍化後，微型發光二極體的外部量子效率提升了4%。同時，我們觀察元件在常溫和高溫高濕(60°C/90%)下的老化特性。老化結果，元件分別經過檸檬酸及硫化銨處理的光輸出僅降解4.41%，相較於未處理的光輸出降解，更少於下降的10.14%。
同時聚焦在鈍化材料的研究，分別以三種不同結構形式的鈍化層成長後對微型發光二極體的特性探討。結果顯示，使用原子層沉積系統沉積125個迴圈的氧化鋁與電子槍蒸鍍系統沉積的分佈式布拉格反射層的組合擁有最佳的特性優化，外部量子效率提升了7.71%，光輸出功率提升了43.27%。
另外，考慮到微型發光二極體的製作流程前，磊晶片本身結構可能直接影響其發光效率。因此，我們分析了含有磷化鎵/磷化鋁銦鎵基底下在不同對數組合的多重量子阱。結果顯示，3對多重量子阱的磊晶結構組合在亮度上提升了34.95%，外部量子效率提高了5.34%。
由於顯示器面板的顏色組合當中另有藍光的微型發光二極體為最常見，因此我們也針對藍光的微型發光二極體進行了側壁處理並探討其特性優化。針對尺寸為5m的藍光微型發光二極體浸泡四甲基氫氧化銨，觀察其對氮化鎵基底的藍光微型發光二極體特性的影響。結果顯示，浸泡後的外部量子效率提升了0.76%。
未來，微型發光二極體將更貼近日常生活。除了改善前製程以提升元件特性外，後續組裝至顯示器端的研究也值得深入思考。這項研究的相關技術將對未來各種新型電子產品，甚至車載應用，帶來顯著的優勢。

Red Micro LEDs are crucial for various applications and demands in display technology, particularly for high-performance displays and specific use cases. Here are the key reasons for the demand for red Micro LEDs, such as wider color gamut, greater stability, independent driving and control, and sensors. In this study, our research aims to enhance the performance of micro light-emitting diodes (micro-LEDs) through innovative sidewall treatments and processing methods. We employed various sidewall treatment methods combined with different deposition techniques and diverse materials to improve the reflectivity of the sidewalls. The performance of micro-LEDs was evaluated using various measurement setups, including Chip on Wafer Electroluminescence (COW-EL) on the wafer and electrical characteristics (Light Output Power (LOP), External Quantum Efficiency (EQE) and Wall-plug efficiency (WPE)) in an integrating sphere.
According to multiple studies, due to the extremely small size of micro-LEDs, sidewall damage caused by inductively coupled plasma (ICP) etching significantly affects performance. Therefore, sidewall treatment is necessary. For red aluminium gallium indium phosphide (AlGaInP) micro-LEDs, we proposed sidewall treatments using citric acid for different durations (0, 30, 60, 90 and 120 seconds) to observe the most effective improvement in performance. Results showed that micro-LEDs treated with CA for 60 seconds had a 31.08% increase in LOP and a 5.4% increase in EQE. Building on this research, we further proposed immediate sidewall passivation after sidewall treatment. After soaking in CA, the samples were soaked in (NH4)2Sx for 1 hour to achieve passivation. After passivation, the EQE of micro-LEDs increased by 4%. We also observed the aging characteristics of the devices at room temperature and under high temperature and high humidity (60°C, 90%). The aging results showed that the light output of devices treated with citric acid and (NH4)2Sx degraded by only 4.41%, compared to the untreated devices, which degraded by 10.14%.
Focusing on the passivation materials, we aimed to observe which combination of passivation layers most effectively enhanced the performance of red AlGaInP micro-LEDs. Results showed that the combination of ALD-deposited 125 loops of Al2O3 and E-Gun-deposited DBR improved the EQE by 7.71% and LOP by 43.27%.
In addition, considering the material structure of the wafer directly influences the brightness of micro-LEDs before the fabrication process, we analyzed multiple quantum wells (MQWs) with different pairs of Well / Barrier. The experiment studied the effect of 3, 7, and 15 pairs of MQWs on the performance of AlGaInP micro-LEDs. Results showed that the micro-LEDs with 3 pairs of MQWs improved brightness by 34.95% and EQE by 5.34%.
Since display panels mostly use RGB colors to form a pixel, with blue light having a significant advantage in emission efficiency, we also performed sidewall treatment on blue micro-LEDs. With the increasing demand for ultra-small micro-LEDs in portable display devices, we conducted sidewall treatment with TMAH on 5m-sized LEDs to observe its impact on the characteristics of blue micro-LEDs on GaN substrates. Results showed that the treated blue micro-LEDs had a 0.76% increase in EQE.

In the future, micro-LEDs will become more integrated into daily life. In addition to improving pre-processing to enhance device characteristics, further research on post-assembly into display devices is also worthy of consideration. The related technologies from this study will bring significant advantages to various new electronic products and even automotive applications.

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