以氫化物氣相磊晶成長非極性氮化鎵基板之研究

Abstract

在本論文中，我們已成功使用氫化物氣相磊晶法成長出厚度為225um的非極性氮化鎵基板，成長方式可分為三步驟，分別是成長氮化鎵厚膜於模板上、雷射剝離得到獨立式氮化鎵基板、再成長氮化鎵厚膜於氮化鎵獨立式基板上。從低溫光激螢光量測可發現隨著非極性氮化鎵基板厚度的增加，NBE的發光強度會增強，但是BSFs的發光強度會變弱，在厚度約225um的非極性氮化鎵基板的量測中，NBE的發光強度甚至比BSFs的發光強度還強。此外，雖然沒有使用黃光製程，但種非極性氮化鎵基板的成長機制，非常類似在m方向開直線圖樣的ELOG成長方式；而這種ELOG的成長方式容易形成孔洞，這些孔洞可以幫助釋放應力，使基板不容易破裂。目前我們已成功成長出厚度為225um的非極性氮化鎵基板，未來，我們相信可以成長出更厚且品質更佳的非極性氮化鎵基板。

In this research, we obtained the non-polar GaN substrate with a thickness of 225um successfully by hydride vapor phase epitaxy(HVPE) using a three-step method which included growing a GaN thick film on the template grown by metalorganic chemical vapor deposition(MOCVD), obtaining the GaN freestanding after laser lift-off, regrowing the GaN thick film on the GaN freestanding. Low temperature photoluminescence of the thick films suggested that the strong near-band-edge(NBE) emission was increasing and the emission of basal stacking faults(BSF) was decreasing as the thickness of the grown films was increased. It was found that the intensity of the near-band-edge emission was stronger than the emission of basal stacking faults when the non-polar GaN substrate was with a thickness of 225um. Particularly, the growth machine of the non-polar GaN substrate was similar to an epitaxially laterally overgrown GaN(ELOG), however, there were not any photolithography processes during the growth process of the GaN substrate. It was easy to form voids which were useful to release stresses. Presently, we can achieve the non-polar GaN substrate with a thickness of 225um. We make sure that the maximum thickness of the non-polar GaN substrate will increase and the quality of the non-polar GaN substrate will be better in the future.