以單晶氮化鎵基板上同質磊晶成長氮化鋁銦鎵系列發光元件之研究

Abstract

經過大約15年的發展，台灣目前是全世界生產最大量氮化鎵光電元件的國家，但全部都是製作 在晶格不匹配的藍寶石基板上。由於氮化鎵和藍寶石有晶格不匹配及熱膨脹係數不相同的問題，因 此衍生出異質磊晶產生的大量缺陷以及基板彎曲現象，缺陷造成元件性能壽命降低而基板彎曲則讓 後續製程變得困難。再則，氮化鎵基板擁有高導電性、散熱性及劈裂容易等多項優異特性。對製作 高電流密度 (例如雷射及高功率元件)及短波長元件而言，使用同質的氮化鎵基板來大幅度提升元件 的效能和簡化製程是必然的選擇。 日本和歐美已經有多個廠商及研究團體進行氮化鎵基板的研發或小量生產，並在氮化鎵基板上 開始進行元件研究，而我國到目前為止沒有任何研究團隊在氮化鎵基板上進行元件製作的研究。究 其原因，主要是因為國內一直沒有建立自主的氮化鎵基板開發能力，而國外的單晶氮化鎵基板又極 其昂貴(約NT300,000元/片)，而且取得困難。有鑒於此，本團隊在一年半以前開始進行製作氮化鎵 基板的研發，截至目前為止，已經累積了相當重要的研究成果，現已能穩定產出1.5吋直徑的氮化鎵 基板供後續實驗使用，也成功示範出2吋直徑的氮化鎵基板，這些成果均為國內首見。藉由此一國內 其他研發團隊所沒有的獨特優勢，我們所提出的計畫是開始在氮化鎵基板上開發同質磊晶的藍光、 近紫外光和紫外光發光二極體，以及藍光、近紫外光半導體雷射，以期將國內的氮化物研究提升到 一個全新的競爭平台上，並為台灣的光電元件研發貢獻心力。

After about fifteen years development, Taiwan is the largest country of manufacturing GaN based optoelectrical devices over the world now. However, they were all made on sapphire substrate in lattice mismatch. Due to the problems of lattice and thermal expansion mismatch between GaN and sapphire, there are huge dislocation densities and bowing of substrate induced through the hetero-epitaxy, which in turn lower the performance and lifetime of the devices and make manufacturing process hard. Moreover, GaN substrate has several excellent characteristics, such as high electrical- and thermal- conductivity and clear cleaves face. To produce high current density (e.x. laser diodes and high power devices) and shorter wavelength devices, the best choice of improving performance and simplifying manufacturing process is using GaN substrate. There have been many factories and research groups in Japan, Europe, and America began to develop the techniques of manufacturing GaN substrate and produced a small amount. Up to today, there is no research group in Taiwan do the study of devices on GaN substrate. This is resulting from the fact that there is no reasrch group in Taiwan has the ability of making GaN substrate, and the foreign GaN substrate is very expensive ( about NT300,000/piece ) and not easy to obtain.To face this challenge, our research group has been developed the GaN substrate manufacturing techniques and got several important results from one and half year ago. Now, we can produce 1.5 inch diameter GaN substrate stably for following study and show 2 inch diameter GaN substrate successfully. And these results are first obviously in Taiwan. By the unique advantages of our research, we will focus the study on the blue, near ultraviolet and ultraviolet light emitting diodes and blue and near ultraviolet laser diodes homoepitaxially grown on GaN substrates in this project. We hope our study can make contribution to optoelectrical devices in Taiwan.