鎳催化劑對於氮化鎵奈米線的成長與特性之研究

Abstract

本實驗使用催化劑輔助的方法藉由自組式水平氫化物氣相磊晶直接將氮化鎵奈米線合成於矽基板上，其前驅物氯化鎵和反應氣體氨氣是藉由純氮氣或氫氮混合氣體來載流。於成長奈米線前我們會先將矽基板浸泡至稀釋後的氫氟酸以去除其氧化層，接著使用電子槍蒸鍍沉積鎳金屬來當催化劑。最後藉由X光繞射儀、掃描式電子顯微鏡、穿透式電子顯微鏡和光激螢光等技術來分析其結構與光性。 我們成功地藉由催化劑輔助的方法成長出高密度的氮化鎵奈米線且其為VSS成長機制。文中我們針對其五三比、成長溫度、載流氣體流量等做討論，發現於低五三比、高溫和低載氣流量下，可有效的使深寬比提高。在光性分析方面，於880度時所生成的氮化鎵奈米線發光帶被紅光發光所主導，這是由於點缺陷所造成的。文中我們藉由調整成長溫度和載流氣體的流量來降低缺陷，並成功的消除紅光發光帶。

In this thesis, we report GaN nanowires (NWs) are directly synthesized on Si (111) through a home-made horizontal HVPE reactor at near-atmospheric pressure. The Si substrates were dipped in a 5% hydrofluoric acid (HF) solution for 10 minutes to remove native oxide. To assist the growth, the 10 nm nickel thin film was deposited on Si substrate as a catalyst using E-gun system. The precursor gas gallium chloride (GaCl) and high-purity ammonia gas are used as the reactant sources for Ga and N atom, respectively. The nitrogen (N2) and hydrogen (H2) were used as a carrier gas throughout the growth process. The structure and optical properties of GaN NWs investigated by XRD, SEM, TEM, and PL will be shown. We demonstrate the growth of GaN NWs on Si from nickel in HVPE. The growth takes place via VSS mechanism. The effects of V/III ratio, growth temperature and carrier gas flow rate are discussed, where all of them are critical in growing GaN NWs. The optimized growth parameters are suggested. The PL were measured at 10K for the NWs grown at different conditions. We propose the growth parameters where the single crystalline GaN NWs can be grown with nice morphology and good blue lighting emission. The control of NWs morphology and lighting property of GaN NWs opens up a pathway for future applications of small lighting transistors.