半導體電激發光致冷元件之降溫極限的探討

Abstract

在本論文中，我們以自洽模型來計算電激發光二極體的冷卻功率，我們探討了在逆偏壓下以載子將能量帶離元件來達到冷卻功率的可能性、雷射輔助發光對正偏壓下的電激發光二極體的冷卻功率的影響，以及可容許電極接面阻抗的最大值；我們也引入了功率守恆方程式來研究電激發光二極體的降溫極限。 我們發現逆偏的操作模式和雷射輔助激發並不適合用來提升元件的冷卻功率。這是因為在逆偏操作模式下的電流值太低；而以雷射輔助激發只有在嚴苛的條件下才有些許的冷卻功率提升。在只考慮熱輻射的理想狀態下，我們發現以GaAs為主動層材料的電激發光二極體，於室溫300 K的環境下其所能達到的最低溫度為112 K，優於以In0.53Ga0.47P為主動材料時的最低溫210 K。

In this thesis, we performed a self-consistent calculation to study the cooling performance of electroluminescent (EL) refrigerators. We investigated the cooling feasibility of an EL cooler under a reverse bias, the influence of the laser pumping on the EL refrigeration, and the limiting contact resistance of an EL cooler. Furthermore, by including the power conservation into our calculation, we can evaluate the ultimate cooling temperature of the semiconductor EL cooler. We showed that neither operating a semiconductor EL cooler at a reverse bias nor applying laser pumping are good methods to improve the cooling capability. This in mainly due to the small current density at the reverse bias and extremely high laser intensity is required to obtain an observable improvement of cooling power. Under the ideal condition that only the thermal radiation is considered, the lowest temperature semiconductor EL coolers with a GaAs active layer can achieve is 112 K. This is better than the lowest temperature 210 K achieved by EL coolers whose active layer is made of In0.53Ga0.47P.