矽單層在銀薄膜上的表面形貌與能譜分析 STS results and STM images of the silicene superstructrue on the Ag(111)/Si(111) surface

Date
2016
Authors
蘇泰龍
SU, Tai-Lung
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Abstract
在文獻中得知可以在單晶金屬表面上成長矽單層結構,在本實驗中Si(111)-(7×7)表面上成長6 ML的Ag(111)薄膜取代單晶銀塊材,然後在成長矽單層結構在銀薄膜上。首先將矽基板經過Flash與熱退火的步驟製成Si(111)-(7×7),然後降至100 K後鍍上6 ML的銀,溫度回到室溫在加熱退火至570 K,等樣品緩慢降至室溫就完成銀薄膜的製備,接著成長矽單層。   要成長矽單層,基底需要維持在500 K以上,在本實驗選擇將銀薄膜維持在550 K,鍍上1 ML的矽,就完成矽單層的製作。在此溫度製備完成的矽單層,可以用STM觀察到四種矽單層結構,分別是4×4、 、兩種 結構,除了結構上再加上STS結果,比較後發現並無差異。   因為基底並非銀塊材,所以用LEED觀察後發現Ag(1×1)會發生錯位,用STM觀察也得到相同的結果,並發現銀薄膜的錯位對矽單層的STS結果並無影響。   但當銀薄膜的厚度不同,會表現不同的特性,在6 ML的銀薄膜上鍍矽可發現矽單層,但在1 ML的銀薄膜上鍍矽卻沒有矽單層,推測鍍上去的矽與銀發生翻轉而往下埋入成為矽基板的一部分,所以6 ML的銀薄膜確實可用來代替銀塊材。
From previous study, we know that we can grow silicene on the metal surface. In this experiment, we grow 6 ML of Ag (111) on Si (111) - (7 × 7) to substituted single-crystal silver bulk, then grow silicene on the silver film. First, we anneal and flash the silicon substrate to form Si (111) - (7 × 7) structure. then deposited 6 ML silver on Si (111) - (7 × 7) structure at 100 K. We warm the sample up to room temperature. Afterward, we anneal the sample to 570 K. Further, we cool down the sample to room temperature. Finally, we complete the preparation of the silver thin film. To Growing the silicene, we need to heat the silver thin film over 500 K. In this experiment, we keep the silver thin film at 550 K and deposit 1 ML Si on it. When the sample cool down, we finish the production of silicene. We can find 4 different silicene structures by STM. They are 4×4 , and two structure. These 4 structure’s STS result are similar. Because we choose silver thin film replace silver bulk. So we can find Ag(1×1) dislocation by LEED . And we also can find same result by STM. But Ag(1×1) dislocation don’t affect STS result. Different thickness of the silver thin film will show different characteristics. We can find silicene on 6 ML silver thin film, but don’t find silicene on 1 ML silver thin film. So we can use 6 ML silver thin film replace silver bulk.
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矽單層, 銀薄膜, , STM, LEED, silicene, silver thin film, silicon, STM, LEED
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