雷射加熱過程中Sb2在Ge(100)晶面上的擴散現象

Sb2 diffusion on the Ge(100) surface upon laser heating

黃美菁(Mei-ching Huang)

指導教授 ： 林登松

國立清華大學/理學院/物理學系/碩士(2013年)

https://doi.org/10.6843/NTHU.2013.00549

摘要

本研究中，主要探討的是利用波長1064nm的DPSS雷射，加熱表面時的變化。雷射照射Ge(100)表面時的溫度，會隨著雷射光和樣品表面法線向量所夾的角度、以及雷射光是否經過viewport有關。而利用雷射作為加熱源，樣品表面降溫速率非常快，有別於傳統的加熱方式，可減少等待樣品降溫的時間。
選用Sb atom吸附於Ge(100)晶面上作為觀察對象，Sb atom吸附於Ge(100)晶面上分為四種型態，以雷射光照射2.5分鐘兩次，討論成對的Sb2（型態C）於加熱其間的運動。經過第一次的雷射照射2.5分鐘後，可將Sb2的運動型態分為六型七類，約有一半的機率，成對的Sb2傾向分成兩個Sb2，並垂直Ge dimer row的方向運動；其次傾向位置沒有改變。而第二次雷射照射時，由於初始狀態的不同，形成了和第一次照射雷射時的差異。針對垂直Ge dimer row的方向，探討位移統計圖分佈不均的現象。並設計程式模擬分子的運動，了解成對的Sb2於雷射照射時的運動行為。根據不同的初始狀態，計算系統的表面活化能：(a)1.005±0.054eV、(b)0.985±0.053eV；兩個Sb2分子間的吸引力大小約為20.0meV。

關鍵字

雷射加熱 ； 銻 ； 鍺 ； 擴散

並列摘要

In this study, we focused on the changes of the Ge(100) surface when the 1064nm DPSS laser heating the surface. The surface temperature related to the angle that sandwiched by laser light and the surface normal vector of the sample. The temperature was also related to whether the laser light was through the viewport. To use the laser as a heating source, the colling rate of the sample surface was very fast. It can reduce the waiting time for cooling the sample, unlike traditional heating methods.
Selected the Sb atom adsorbed on Ge (100) crystal face as the observation object, it can be divided into four types. Type C is our investigation. After the first 2.5 minutes laser heating, we can divide the molecular motion of Sb2 into six types (seven categories). There is about half of the pair of Sb2 molecules that tend to divide into two Sb2 molecules separately, and it moved perpendicular to the direction of the Ge dimer row. Secondary the position of the pair of Sb2 did not change. And by the second laser heating, the motion was difference with the first due to the different initial state. For the direction perpendicular to Ge dimer row, we explored the uneven distribution about the displacement diagrams. In addition, we wrote the programs to simulate the movement of molecules in order to understand the motion of pair Sb2 when the laser heating. Final, by different initial state, we calculated the activation energy by diffusion which was (a)1.005±0.054eV and (b)0.985±0.053eV. The force of attraction between two Sb2 was 20.0meV.

並列關鍵字

laser ； Sb2 ； Ge(100) ； diffusion

參考文獻

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