本論文共分成二個部分，第一部分利用定順向偏壓法(constant-forward-voltage method)進行高功率GaN-based發光二極體的熱阻量測，以致冷晶片控溫(Thermoelectric controller , TEC)系統進行主動式的控溫，建立發光二極體一階封裝後的熱傳路徑分析，提升量測速度、可靠度及準確度的能力。本研究分析高功率GaN-based發光二極體封裝於不同厚度的銅基板上之熱阻，發現銅基板厚度較薄時，主要熱傳路徑為熱擴散(spreading thermal resistance, Rs)路徑所主導，隨著厚度的增加，熱阻會下降，當厚度達到一定值後，擴散熱阻(Rs)會達到最小值，之後當厚度再增加，熱阻則會上升，此時則為一維熱傳路徑(1-D thermal resistance, Rz)所主導。此外，本論文也探討，除了熱傳導路徑之外，熱對流路徑的對高功率GaN-based發光二極體熱阻量測的影響。在熱阻的量測過程中，我們發現GaN薄膜在電流注入後會產生滯彈應變。GaN-based化合物為壓電材料，滯彈應變的產生會誘導額外的壓電場存在於GaN磊晶薄膜中，進而影響GaN-based LED的光電特性。因此，本論文第二部分為研究滯彈應變的產生及對於GaN-based發光二極體的光電特性的關係。同時，根據文獻指出，滯彈應變的主要原因機制，為材料本身的缺陷所造成，因此，本論文中同時也探討滯彈應變的鬆弛時間(Relaxation time)與外加電場、GaN磊晶薄膜溫度及GaN磊晶薄膜內缺陷密度之間的關係，獲得關於GaN磊晶薄膜缺陷密度的資訊。 This study discusses that the thermal resistance measurement of GaN-based LED and the effect by the presence of anelastic strain resulted in the GaN epi-layers. In the Chapter 3, the thermal resistance of the first-level Cu dissipation substrate (RCu) with different Cu substrate thickness is investigated. Using the “constant-forward-voltage” method, the thermal resistances of the first-level Cu dissipation substrates (RCu) were measured against different Cu substrate thickness. The thermal resistance (RCu) of the Cu substrate is composed of the z-direction thermal resistance (Rz) and the two-dimensional horizontal spreading resistance (Rs). After the initial increase in RCu, the RCu would increase and be dominated by the Rz increase with the Cu substrate thickness. Intriguingly, a minimum RCu value occurs at the Cu substrate thickness of about 1 mm. Chapter 4 discusses the presence of anelastic strain in the GaN epi-layers. Owing to the piezoelectric field properties of the GaN-based compounds, optical and electric properties are proved to be greatly influenced by the piezoelectric field induced in the GaN-based LED. Chapter 5 study the detail factors of anelastic strain relaxation and attempt to understand the defects by monitoring the electrical and optical properties of GaN-based LED.
