發光二極體一階封裝散熱銅基板熱阻量測與氮化鎵薄膜的應變滯彈現象研究; Study of thermal resistance measurement of first-level Cu substrate and the anelastic behavior in GaN-based LED

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Title:	發光二極體一階封裝散熱銅基板熱阻量測與氮化鎵薄膜的應變滯彈現象研究;Study of thermal resistance measurement of first-level Cu substrate and the anelastic behavior in GaN-based LED
Authors:	楊鈞珽;Yang,Chun-ting
Contributors:	化學工程與材料工程學系
Keywords:	發光二極體;LED封裝;熱阻量測;壓電效應;滯彈效應;Light-emitting diode;LED package;thermal resistance measruement;piezoelectric effect;anelastic effect
Date:	2013-08-16
Issue Date:	2013-10-08 15:07:18 (UTC+8)
Publisher:	國立中央大學
Abstract:	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.
Appears in Collections:	[National Central University Department of Chemical & Materials Engineering] Electronic Thesis & Dissertation

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