鎳在銀/矽(111)-(√3 × √3 )表面上聚集分布和熱力衍化的研究

The condensation, distribution, and the phase transformation of Ni on Ag/Si(111)-(√3×√3) surfaces

張國偉

指導教授 ： 傅祖怡

國立臺灣師範大學/理學院/物理學系/碩士(2011年)

摘要

蒸鍍鎳原子於銀/矽(111)-(√3×√3)表面上，變化其鍍量和溫度，並藉由STM觀測鎳原子的聚集分布和熱力衍化。固定溫度於室溫改變鍍量，鎳原子會形成鎳原子團，若鍍量大於0.2 ML，部分鎳原子團會合併形成鎳島，且鎳原子團與鎳島均隨鍍量上升而逐漸變大。
固定鍍量改變溫度，含鎳原子團在300℃以下會逐漸向銀島邊緣聚集，且於300℃逐漸形成外型為幾何形的Ni2Si-δ(2×1)島，並於200~300℃有往塊材擴散的行為，由銀島交界處鑽入裡層，使得表面鎳鍍量下降，於400℃銀原子開始退吸附，使原先被銀覆蓋住的鎳矽化合物變成NiSi2再度露出表面。
升溫至600、700℃時，銀原子已經完全退吸附，而鎳原子仍在矽(111)表面上，其表面形貌主要為，矽(111)-(7×7)、原子團、鎳矽1×1-RC和NiSi2(B)(鍍量超過1.4 ML才會出現)，並藉由STS得知，鎳矽1×1-RC的電性頗為類似N型半導體，而NiSi2(B)類似於金屬電性。

關鍵字

鎳 ； 矽 ； 銀 ； 銀/矽-(√3 × √3 )

並列摘要

The condensation, distribution, and the phase transformation of Ni on Ag/Si(111)-(√3×√3) surfaces were investigated by STM. When the temperature was fixed at room temperature(RT) and the coverage of Ni deposition was controlled, we found the Ni clusters and Ni islands formed. When the coverage of Ni was smaller than 0.2 manolayer(ML), only Ni clusters were formed. As the coverage was increasing, the size of Ni clusters and islands was increasing.
When the coverage of Ni deposition was fixed and the annealing temperature was controlled, the structure transformation of Ni-included clusters and islands was found. When the temperature was below 300℃, clusters condensated on the step edge of Ag/Si(111)-(√3×√3) substrates. The Ni2Si-δ(2×1) islands with geometric shape formed after 300℃annealing. When the temperature ranged from 200℃ to 300℃, Ni diffused into the inner layer from boundary of Ag/Si(111)-(√3×√3). The phenomenon leaded to Ni coverage on the surface decreasing. Ni silicide transforms to NiSi2 at 400℃; meanwhile, desorption of partial Ag atoms results in NiSi2 appearing on the surface again.
Ni-included structures still appeared on the Si(111) surface after all Ag atoms had desorbed at 600℃. The surface topography included Si(111)-(7×7), Ni-included clusters, 1×1-ring cluster(RC) silicide, and NiSi2(B) which was found at Ni coverage over 1.4 ML. Electric properties of 1×1-RC silicide is very similar to N type semiconductors, and electric properties of NiSi2(B) is similar to conductors by STS.

並列關鍵字

Ni ； Si ； Ag ； Ag/Si-(√3 × √3 )

參考文獻

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