篇題：Selective area growth of InAs nanowires from SiO2/Si(1 1 1) templates direct-written by focused helium ion beam technology
文章出處：Journal of Crystal Growth vol. 484, pp. 56-63, 2018.
作者：Che-Wei Yang, Wei-Chieh Chen, Chieh Chou, and Hao-Hsiung Lin
任職單位及部門：台灣大學電子工程學研究所、光電工程學研究所、電機工程學系
We report on the selective area growth of InAs nanowires on patterned SiO2/Si (1 1 1) nano-holes, prepared by focused helium ion beam technology. We used a single spot mode, in which the focused helium ion beam was fixed on a single point with a He+-ion dosage, ranging from 1.5 pC to 8 pC, to drill the nanoholes. The smallest hole diameter achieved is ~8 nm. We found that low He+-ion dosage is able to facilitate the nucleation of (1 1 1)B InAs on the highly mismatched Si, leading to the vertical growth of InAs nanowires (NWs). High He-ion dosage, on the contrary, severely damaged Si surface, resulting in tilted and stripe-like NWs. In addition to titled NW grown from (1 1 1)A InAs domain, a new titled growth direction due to defect induced twinning was observed. Cross-sectional TEM images of vertical NWs show mixed wurtizite (WZ) and zincblende (ZB) phases, while WZ phase dominants. The stacking faults resulting from the phase change is proportional to NW diameter, suggesting that the critical diameter of phase turning is larger than 110 nm, the maximum diameter of our NWs. Period of misfit dislocation at the InAs/Si interface of vertical NW is also found larger than the theoretical value when the diameter of heterointerface is smaller than 50 nm, indicating that the small contact area is able to accommodate the large lattice and thermal mismatch between InAs and Si.
文章摘要：
我們報告了利用聚焦氦離子束技術製備圖案化 SiO2/Si (1 1 1) 納米孔模板，並於其上進行 InAs 納米線的選擇性區域生長。我們使用單點模式，將氦離子束固定聚焦在單點上，He+ 離子劑量範圍從 1.5 pC 到 8 pC，以鑽出納米孔。實現的最小孔徑為~8 nm。我們發現低 He+ 離子劑量能夠促進 (1 1 1)B InAs 在高度失配的 Si 上成核，從而導致 InAs 納米線 (NW) 的垂直生長。相反，高 He+ 離子劑量會嚴重損壞 Si 表面，導致傾斜和條紋狀 NW。除了從 (1 1 1)A InAs 域生長的傾斜NW 之外，還觀察到由於缺陷引起的孿晶導致的新傾斜生長方向。垂直 NW 的橫截面 TEM 圖像顯示混合纖鋅礦 (WZ) 和閃鋅礦 (ZB) 相，而 WZ 相占主導地位。由相變引起的堆疊層錯與 NW 直徑成正比，表明相轉變的臨界直徑大於 110 nm，即我們 NW 的最大直徑。當異質接面直徑小於 50 nm 時，垂直 NW 的 InAs/Si 界面的錯配位錯週期也大於理論值，表明小接觸面積能夠適應 InAs 和Si之間的大晶格失配和熱失配。