透過氫化物氣相磊晶法探討利用多變化 金屬合金催化劑成長氮化鎵奈米線

Abstract

本實驗利用氫化物氣相磊晶，藉由金屬催化的方式成長氮化鎵奈米線於矽基板(Si (111))上，探討奈米線成長機制以及奈米線與金屬催化劑的關係，並研究磊晶參數對藉由金屬催化成長之氮化鎵形貌的影響。首先將矽基板浸泡於H2O:HF=10:1的溶液10分鐘以去除其自生氧化層，再利用電子束蒸鍍於矽基板上分別沉積金、金鎳合金、金銀合金以及金錳合金作為催化金屬，最後送入氫化物氣相磊晶機台成長氮化鎵奈米線。 在探討奈米線成長機制以及奈米線與金屬催化劑的關係中，發現利用金、金鎳合金、金銀合金以及金錳合金作為催化金屬下，所統計出的氮化鎵奈米線成長方向皆為[101 ̅0]，這也代表我們可以利用多變化的合金金屬來達到性質相同的氮化鎵奈米線，以提供製程上更多的選擇。成長過程中，催化金屬－金、金鎳合金、金銀合金以及金錳合金都能保有完整的液滴形狀，以利分析催化金屬的相關特性。 在研究磊晶參數對藉由金屬催化成長之氮化鎵形貌的影響中，調變溫度、氨氣與氯化氫氣體流量比(Ⅴ/Ⅲ比)，觀察其對成長趨勢的變化，並且發現產生之形貌與金屬催化成長機制有關，磊晶參數之調變改變沉積至矽基板之反應氣體濃度，進而影響金屬催化成長過程中，軸向成長與徑向成長之速度，瞭解磊晶參數之影響趨勢後，我們已經可以穩定地於矽基板上製備氮化鎵奈米線。

We use metal-catalyzed method to grow GaN nanowires on Si(111) substrate by hydride vapor phase epitaxy (HVPE). The buffered hydrofluoric acid is used to etch the native oxide on Si(111) substrates. Au, Au-Ni, Au-Ag and Au-Mn alloy films are deposited on the Si(111) substrates using electron beam evaporation. GaN nanowires are then grown on the Si(111) substrate using HVPE. The growth mechanism of nanowires and the epitaxy between nanowires and substrate are investigated. In addition, the growth at different temperatures, Ⅴ/Ⅲ ratios and the amounts of carrier gas flow are discussed.

We find that the Au-Ni alloy catalyzed and Au-Mn alloy catalyzed nanowires are observed the interface between catalyst and GaN crystal structure apparently, which are grown via VLS and VSS mechanisms. However, the Au catalyzed and Au-Ag alloy catalyzed nanowires are unstable during the growth process that is contribute to the unapparent interface, which are grown via VLS mechanisms. The orientation of GaN nanowires via different catalysts are grown all along [101 ̅0] on Si(111) substrate. The PL were measured at 300K for the nanowires 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. We discuss the growth and process parameters, which influence the concentration of the deposited reactants, and the growth mechanisms of the nanowires. We suggest the process parameters for stably producing GaN nanowires on Si(111) substrate.