石墨烯是一種由碳原子組成的二維材料，為六角形的蜂巢結構。其具備低片電阻、高導熱率、機械性和高電子遷移率等特性，其中在紫外光波段下，單層石墨烯具有良好的穿透率，比起氧化銦錫(ITO)，更適合作為紫外光發光二極體(UVC-LED)的透明導電層。本研究利用低壓化學氣相沉積系統在銅箔上生長石墨烯，並利用轉貼法將石墨烯轉移至UVC-LED基板，透過拉曼光譜圖分析，其ID/IG為0.12、I2D/IG為2.33、FWHM2D為29.7 cm-1，是為高品質的單層石墨烯。
為了進一步提高UVC-LED的發光強度，在石墨烯上鍍上一層極薄鎳層，利用高溫製程的除潤現象使表面形成鎳奈米粒，於UVC-LED上製備出鎳奈米粒/石墨烯複合電極。本研究首先通過調整鎳層厚度、高溫退火製程的溫度及時間，來控制鎳奈米粒的大小並降低鎳奈米粒/石墨烯的電阻率，其最低可達650 Ω-cm。 接著以高真空熱蒸鍍系統製備金屬電極，進行光電特性分析以及熱特性量測。而利用除潤現象製備出的鎳奈米粒/石墨烯，其穿透率在紫外光波段為72 %，相比ITO的低穿透率提升許多。透過電致發光量測，可以發現鎳奈米粒/石墨烯複合電極樣品比起傳統鎳金電極樣品，其發光強度在100 mA下增加20倍。在真空腔體下進行注入電流與晶粒溫度量測，於室溫下注入電流100 mA後，傳統鎳金電極溫度上升35 ℃，而鎳奈米粒/石墨烯複合電極樣品僅上升11 ℃。本研究製備出鎳奈米粒/石墨烯複合電極可作為UVC-LED的電流擴散層，有助於改善大電流下產生的電流擁擠效應，使UVC-LED的發光強度增加，並且實質改善元件散熱的問題。

Graphene is a two-dimensional material composed of carbon atoms in a hexagonal structure. It has the characteristics of low sheet resistance, high thermal conductivity, mechanical properties, and high electron mobility. Among them, monolayer graphene has good properties in the ultraviolet light band. Compared with Indium Tin Oxide (ITO), it is more suitable as a transparent conductive layer for ultraviolet light-emitting diodes. In this study, graphene is grown on copper foil using a low-pressure chemical vapor deposition method. A PMMA-mediated transfer method is used to transfer the graphene to the UVC-LED substrate. Through Raman spectrum analysis, the ID/IG is 0.12, I2D/IG is 2.33, and FWHM2D is 29.7 cm-1. It is a monolayer of very high-quality graphene.
In order to further improve the luminous intensity of UVC-LED, an extremely thin layer of Ni is then plated on the graphene, and the dewetting phenomenon caused by the high-temperature process is used to form Ni nanodots/graphene hybrid electrode on UVC-LED. This study first controls the size of Ni nanodots and reduces the resistivity of Ni nanodots/graphene by optimizing the thickness of the Ni layer, the temperature, and time of the high-temperature annealing process, which can reach a minimum resistivity of 650 Ω-cm. Then, a high vacuum thermal evaporation system is used to prepare metal electrodes, and optoelectrical characteristics analysis and thermal measurement are performed. The Ni nanodots/graphene prepared by utilizing the dewetting phenomenon have a transmittance of 72 % in the ultraviolet light band, which is much higher than the low transmittance of ITO. Electroluminescence investigation shows that the UVC-LED of the Ni nanodots/graphene hybrid electrode sample manufactured using nickel has a luminous intensity that is 20 times greater than that of the standard nickel-gold electrode sample at 100 mA. A vacuum chamber was used to measure the chip temperature. The temperature of the conventional nickel-gold electrode was raised by 35 °C after a 100 mA current injection at room temperature, but the temperature of the Ni nanodots/graphene hybrid electrode sample only increased by 11 °C. In this study, Ni nanodots/graphene hybrid electrode was manufactured as the current diffusion layer of UVC-LED. This helps to reduce the issue of component heat dissipation and improves the current crowding effect caused by high currents.

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