發光二極體(Light-Emitting Diode, LED)由於磊晶缺陷、電極佈置等原因，造成發光層局部區域電流密度較高，此現象稱為電流集聚效應(Cureent Crowding Effect)。然而電流密度較高不只造成發光強度增加，也代表溫度升高並形成區域加熱現象(Local Heating)。此外，當溫度提高時電子與電洞在發光層的非輻射結合的機率提高，且全反射效應(Total Internal Reflection)也讓反射回來的能量會被LED各層材料吸收，而這又使得溫度提高。在上述效應交互作用之下，LED產生自體加熱效應(Self Heating)並減少自身壽命甚至損壞封裝材料。因此LED溫度量測顯得更重要。
由於LED的晶粒尺寸很小，難以使用接觸式的溫度量測方式，所以本論文利用非接觸式的溫度量測方式(熱像儀, Infrared Camera)。然而在量測溫度前，需先知道LED每個材料的放射率(Emissivity)，量測的溫度才正確。所以將黑色電汽絕緣膠帶當作黑體校正源，並分別量測LED表面材料之放射率。得到各表面材料放射率後，套用在已封裝完成之LED上，並取得各材料的表面溫度，最後再與順向偏壓法所推測出的接面溫度做比對。

This current crowding effect of light-emitting diode (LED) resulted from the defects in the epilayers or arrangement of electrodes, and caused higher current density in partial region of light emitting layer. Since higher current density not only means higher light output, but also cause temperature rising and cause localized heating. Besides, the increasing non-radiative combination rate of of electrons and holes in emission layer of LED, and the total internal reflection effect also enhanced the temperature rise. Due to the abovementioned effects, the resulting self-heating effect reduces lifetime of LED and even do damage to epilayer materials. Therefore, LED chip temperature measurement becomes more important.
Because of the size of LED chips is very small, is difficult to measure temperature by using contact thermometer. In this thesis, the non-contact thermometer (infrared camera) was used to measure LED chip surface temperature. However, the knowledge of emissivity for each epilayer materials is required to test the real temperature of LED surface epilayer. A black electrical insulation tape was used as a reference black body and referred to measure emissivity of each LED epilayer materials. After emissivity calibrating, the surface temperature of LED chip was tested by applying the emissivity of epilayers. Then, the temperature measured by infarred camera was compared with the temperature calculated by forward voltage method.

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