臺灣博碩士論文加值系統

本論文以雙電子槍蒸鍍系統製備p-GaN的藍光反射式歐姆電極AgPt(6 at%)、AgPt(4 at%)、AgPt(2 at%)、Pt(2 nm)/Ag(150 nm)、AgRh(2 at%)及AgRu(2 at%)等六組試片，探討不同合金成分以及爐管退火(FA)與快速退火(RTA)兩種退火方式對於藍光反射式歐姆電極光電特性與熱穩定性的影響。探討內容包含歐姆電極的藍光反射率、金屬薄膜片電阻與特徵接觸電阻，以及各性質之熱穩定性。並使用掃描式電子顯微鏡觀察試片表面樣貌，分析不同合金成分的特性差異及抑制退火後Ag薄膜凝聚(agglomeration)的效果。我們發現AgPt(2 at%)、Pt(2 nm)/Ag(150 nm)皆無法抑制Ag的凝縮，AgPt(4 at%)及AgPt(6 at%)能抑制薄膜的高溫退火凝聚。而AgRh(2 at%)與AgRu(2 at%)合金薄膜經500 ℃退火後表面未發現明顯破孔；但AgRu(2 at%)經爐管退火再於400 ℃時效1小時後有些許破孔產生，因此造成反射率下降。其他試片經爐管退火或快速退火，且經400 ℃時效退火1小時後反射率變化不大。六組試片的金屬薄膜片電阻都小於1 Ω/□，且具熱穩定性。在特徵接觸電阻上，AgPt合金於退火後的特徵接觸電阻會隨著Pt成份的增加而下降，但在Pt添加的量大於4 at%時，AgPt再經時效時Ag會產生側向擴散，引發電極漏電現象；而AgRh(2 at%)與AgRu(2 at%)的特徵接觸電阻數值皆具良好熱穩定性。整體來說，AgRu(2 at%)表現最佳，經大氣環境500 ℃快速退火1分鐘後，可以於460 nm藍光具93%的光反射率，金屬薄膜片電阻約為0.2Ω/□，特徵接觸電阻約為7.4× 10-4 Ω-cm2且具良好熱穩定性。另外也可以看出在Ag與少量貴金屬(Pt, Ru, Rh)形成合金時，貴金屬元素本身功函數的大小不是影響特徵接觸電阻值大小的主要原因。

In this study, all the samples AgPt(6 at%), AgPt(4 at%), AgPt(2 at%), Pt(2 nm)/Ag(150 nm), AgRh(2 at%) and AgRu(2 at%) were deposited on the p-GaN by dual E-gun evaporation system. The samples were annealed at 500℃ by two different annealing conditions, furnace annealing(FA) in air ambient for 10 min, and rapid thermal annealing(RTA) in air ambient for 1 min. Thermal stability test were performed by annealing at 400℃in air ambient for 60 min. Optoelectricproperties and thermal stability of p-GaN/AgPt, p-GaN/AgRu and p-GaN/AgRh reflective ohmic contacts were investigated by SEM analysis, reflectance at 460 nm, sheet resistance of metal film , and specific contact resistance.The result show annealed AgPt(6 at%), AgPt(4 at%),AgRh(2 at%) and AgRu(2 at%) could suppress the agglomeration of Ag film.In AgPt(6 at%) and AgPt(4 at%),Ag would produce lateral diffusion causing electrode leakage phenomenon when aging at 400 ℃ for one hour. Comprehensive consideration above-mentioned properties,AgRu (2 at%) alloys thin films are excellent.After anneal 1min in air at 500 ℃, the AgRu(2 at%) reflectors produce low specific contact resistance(7.4 × 10-4 Ω-cm2), high reflectivity(93% at 460nm),good sheet resistance of the metal thin film(0.2 Ω/□), and good thermal stability. Otherwise, we could also find that the work function of the magnitude of the noble metal element itself could't be the main cause of the magnitude of the specific contact resistance ,when small amount of Ag and a noble metal (Pt, Ru, Rh) alloy is formed.

摘要 I
致謝 II
目錄 III
表格目錄 IV
圖片目錄 V
第一章 緒論
1-1 前言 1
1-2 基本理論 3
1-3 文獻回顧 8
1-4 研究動機與目的 11
第二章 實驗
2-1 試片設計 13
2-2 實驗方法 14
第三章 結果與討論
3-1 SEM影像分析 18
3-2 退火對各試片光反射率及其熱穩定性的影響 19
3-3 退火對金屬薄膜片電阻及其熱穩定性的影響 21
3-4 CTLM量測結果與分析 22
第四章 結論 25
參考文獻 27
表格 表1 ~ 表5
圖片 圖1 ~ 圖53

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