本論文主要利用電子束蒸鍍技術來蒸鍍氧化鋅鋁摻雜釔(AZO:Y2O3 ; AZO:Y)之透明導電薄膜，有別於過去常用的濺鍍法(Sputtering)來成長氧化鋅(ZnO)薄膜系列，文中首先對於AZO:Y透明導電薄膜進行光電特性之量測分析以及其在P型氮化鎵(p-GaN)上之歐姆接觸特性研究，最後，將此薄膜成長於氮化鎵藍色發光二極體上與傳統透明導電薄膜-氧化銦錫(ITO)作比較，探討兩者應用於氮化鎵藍色發光二極體上之光電特性的差異。
由實驗可知，在成長溫度350℃下，蒸鍍AZO:Y薄膜於玻璃基板上，未經熱處理即有最低的電阻率6.95×10-4Ω-cm，遷移率(mobility)為45.1cm2/V-s及載子濃度(carrier concentration)為-1.99×1020 cm-3，而在可見光波段，光穿透率皆高於90%。將此AZO:Y薄膜直接成長在P型氮化鎵上做為透明電極，與傳統ITO透明電極做比較，不需任何熱處理，ITO薄膜及AZO:Y薄膜與P型氮化鎵皆可以有良好的歐姆接觸，其特徵接觸電阻(ρc)分別為2.95×10-2Ω-cm2與3.36×10-2Ω-cm2，經熱處理後，AZO:Y薄膜與P型氮化鎵間之歐姆接觸特性比ITO薄膜具有更好的熱穩定性，即在高溫熱處理下，AZO:Y薄膜與P型氮化鎵仍有良好不變的歐姆接觸特性。
比較不同溫度熱處理後之不同透明導電膜(AZO:Y及ITO)應用在氮化鎵藍色發光二極體上。在20mA 注入時，AZO:Y TCL LED不受高溫熱處理影響，其順向導通電壓(Vf)在熱處理前後皆約為3.3V；而ITO TCL LED 隨著熱處理溫度升高，Vf逐漸變大，未經熱處理時有著最低Vf為3.27V。因此，AZO:Y透明導電薄膜應用於氮化鎵藍色發光二極體上之元件特性有良好的熱穩定性。
比較最佳製程條件(未經熱處理)下，不同透明導電薄膜(AZO:Y及ITO)應用在氮化鎵藍色發光二極體上之光特性，AZO:Y TCL LED之光輸出功率為5.49mW比ITO TCL LED之光輸出功率4.93mW增加約11.4%，其光輸出功率增加的原因可歸因於AZO:Y 薄膜有較高之光穿透率。
經本研究可知，AZO:Y與ITO薄膜應用於氮化鎵發光二極體上之電特性有相同好的表現，而AZO:Y TCL LED具有良好之熱穩定性，再者，AZO:Y薄膜又具有比ITO薄膜之高光穿透率及折射係數，因此，AZO:Y薄膜極具有替代ITO薄膜應用在氮化鎵發光二極體(GaN-based LED)上之潛力與可能性。

In this study, the conductive transparent AZO:Y2O3 (AZO:Y) thin films were deposited by electron-beam evaporator. The resistivity of the as deposited AZO:Y film by sputter is more than 1.00×10-2Ω-cm. However, the resistivity of AZO:Y thin films deposited at 350oC without any thermal annealing could be lowered to 6.95×10-4Ω-cm and had optical transmittance more than 90% in visible regions.
We had demonstrated the electrical properties and the optoelectrical characteristics of AZO:Y and ITO transparent contact layers (TCL) onto p-GaN and LEDs, respectively with different thermal annealing temperatures. The AZO:Y/p-GaN and ITO/p-GaNcontacts exhibited a Ohmic electrical characteristic without thermal annealing. The specific contact resistance of as-dopsited AZO:Y and ITO contact on p-GaN were 3.36×10-2 and 2.95×10-2 Ω-cm2, respectively. The specific contact resistance of AZO:Y/p-GaN was almost the same as the same as deposited AZO:Y/p-GaN after thermal annealing in 500~800 oC for 1 min in N2 ambient. The AZO:Y thin films contact onto p-GaN shows the better thermal stability than the ITO/p-GaN.
The forward voltage(Vf) at 20mA of the LEDs with AZO:Y TCL with annealing temperatures of as-deposit, 500, 600, 700 and 800 were 3.3V, 3.31V, 3.32V, 3.31V, 3.29V, respectively. And the output power of LED with AZO:Y TCL decreased with increasing the annealing temperature.
The LED with ITO TCL were processed to compare with the LED with AZO:Y TCL. The Vf (output power) at 20mA of the AZO:Y and ITO TCL LEDs were 3.30V(5.49mW) and 3.27V(4.93mW), respectively. The Vf of the LED with AZO:Y TCL was almost the same as the LED with ITO TCL under 20mA current injection. However, the light output power of the LED with AZO:Y TCL is 11.4% higher than the LED with ITO TCL under 20mA current injection. The improvement of the output power of LED with AZO:Y could be from the fact that the light transmittance of AZO:Y thin film is higher than which of ITO thin film.
It is highly probable and promising that the AZO:Y thin film deposited by electron-beam evaporator could be a replacement to ITO thin film for transparent electrode application on GaN-based light-emitting diode.

[1] Xu Zi-qiang, Deng Hong, Li Yan, Cheng Hang, Materials Science in Semiconductor Processing 9, 132–135 (2006)
[2] J. G. Lu, S. Fujita,_ T. Kawaharamura, H. Nishinaka, Y. Kamada, T. Ohshima, Z. Z. Ye, Y. J. Zeng, Y. Z. Zhang, L. P. Zhu, H. P. He, B. H. Zhao, J. Appl. Phys. 101, 083705 (2007)
[3] Kai-Ming Uanga, Shui-Jinn Wang , Shiue-Lung Chen, Tron-Min Chen, Bor-Wen Liou, Thin Solid Films 515, 2501–2506 (2006)
[4] June O Song, Kyoung-Kook Kim, Seong-Ju Park, and Tae-Yeon Seong, Appl. Phys. Lett. 83, 3 (2003)
[5] Chun-Ju Tun, Jinn-Kong Sheu, Bao-Jen Pong, Min-Lum Lee, Ming-Yu Lee, Cheng-Kang Hsieh, Ching-Chung Hu,and Gou-Chung Chi, IEEE Photonics Technol. Lett. 18, 1 (2006)
[6] 呂彥興, “氧化鋅鎵薄膜成長在氮化鎵發光二極體上之應用”,國立成功大學光電與工程研究所，碩士論文（2007）
[7] X. A. Cao, S. J. Pearton, A. P. Zhang, G. T. Dang, F. Ren, R. J. Shul, L. Zhang, R.Hickman, and J. M. Van Hove, Appl. Phys. Lett. 75, 2569 （1999）
[8] 施敏, 半導體元件物理與製作技術, p.96
[9] Dieter K. Schroder, Semiconductor material and device characterization, p.146
[10] 彭立琪, “氧化鋅鋁摻雜釔之透明導電薄膜材料特性與其應用在氮化鎵藍色發光二極體之研究”,國立成功大學光電與工程研究所，碩士論文（2007）.
[11] E. Fred Schubert, Light-emitting diodes, second edition, p.92, p.133~p.138