利用氫化物氣相磊晶法在雲母基板上成長氮化鎵之研究

Abstract

本實驗利用氫化物氣相磊晶法，藉由凡德瓦爾力將氮化鎵成長在雲母基板上，並嘗試找到氮化鎵最好品質以及最佳的發光特性。目前光電產業在氮化鎵磊晶上有相當成熟的技術，由於現今科技對於可撓式光電產品有所需求，若我們能將氮化鎵磊晶技術成功轉移到可撓式的基板上，對於市場需求會有很大的進展，目前成長氮化鎵的基板除了氮化鎵本身還有碳化矽、藍寶石，以及矽基板，然而以上這些基板都無法達到可撓式的需求，所以我們希望透過雲母可彎曲的特性，在其上做氮化鎵的異質磊晶，進而發展成可撓式的發光元件，因此我們選用雲母當基板去成長氮化鎵。 本實驗主要分成高溫製程以及低溫製程，高溫的部分以二階段成長加入熱退火的步驟，改善氮化鎵與基板黏滯性的問題，並且取得最佳品質以及發光特性的氮化鎵；而為了改善在高溫製程時，氮化鎵呈現灰黑表面的情況，我們改變製程方式，利用電子束蒸鍍機與氫化物氣相磊晶機台在雲母基板上成長氮化鎵，並成功製備出低溫氮化鎵。 在這裡，我們透過氫化物氣相磊晶機台（HVPE）以快速的生長速率成長氮化鎵，並利用X射線搖擺曲線與螢光激發光譜探討在不同溫度下以及加入不同條件的緩衝層後的氮化鎵的品質以及發光特性。

In this experiment, we have fabricated GaN epitaxial film on muscovite mica via van der Waals force by Hydride Vapor Phase Epitaxy (HVPE). A technique that permits high-quality crystalline grown on a flexible substrate directly may be critical for developing flexible electronic devices. Accordingly, we use muscovite mica as flexible substrate for heteroepitaxial growth. Despite the large lattice mismatch between GaN and muscovite mica, we have successfully grown GaN epitaxial film on mica substrate via van der Waals bonding. However, the poor adhesion between GaN epitaxial layer and mica substrate is attributed to the disparity of their thermal expansion coefficient. Hence, we introduce a two-step growth and additional annealing step for GaN epitaxial layer to improve the adhesion and thus to enhance the quality. Though we have found the optimized condition in this part, we still have problem with opaque GaN epitaxial film. Therefore, we change the growth mechanism into low-temperature fabrication and modulate the thickness of capping layer to find the best condition for high quality transparent GaN film. Here we fabricate GaN films grown on mica by hydride vapor phase epitaxy (HVPE) in a rapid growth rate. The X-ray rocking curve (XRC) and photoluminescence (PL) results will be shown. The comparison of the quality of GaN epitaxial film at both high- and low- temperature fabrication process will be discussed.