雷射加熱引發D2 由Ge(100) 晶面熱脫附與表面結構變化

Laser Thermal Desorption of D2 from the Ge(100) Surface Studied by Scanning Tunneling Microscopy

楊舜富(Yang, Shun Fu)

指導教授 ： 林登松

國立清華大學/理學院/物理學系/碩士(2016年)

摘要

本論文中，主要探討以雷射加熱樣品D/Ge(100)表面的一系列的熱反應變化，並且用穿隧電子顯微鏡來研究觀察。在此一系列的變化中，有一熱反應為第一階熱脫附反應，此反應對溫度極為敏感，並可利用此反應對溫度量測做校正。
最初樣品是以室溫成長的D/Ge(100)表面，它是由1×1 ,2×1和 3×1結構所混合組成的。在雷射加熱樣品的過程中，隨著樣品溫度上升表面結構變的有序，並切在不同的溫度區間將由3×1或 2×1結構為表面結構的主體。而當溫度上升至530 K，表面懸鍵明顯增加，其中孤懸鍵 (single dangling bonds) 為對懸鍵 (paired dangling bonds) 的0.15倍。而當溫度超過550 K，表面重構出鍺鏈，甚至組成鍺島。雷射加熱樣品達到530 K及超過550 K的表面熱反應結果讚先前的研究會發現過。
最後利用第一階熱脫附反應來對溫度量測做一個校正的動作，此反應溫度約為530 K，而被校正的量測工具為遠紅外線熱像儀的測量以及簡易物理模型模擬的結果。

關鍵字

溫度 ； 氘 ； 氫 ； 鍺(100) ； 熱脫附 ； 雷射加熱

並列摘要

In this study we used a 532nm DPSS Laser to heat the D/Ge (100) surface induce a series of thermal reactions; these reactions have been investigated by scanning tunneling microscopy (STM). Each of the reactions depend on surface temperature. One of these thermal reaction is the first order thermal desorption. Under the first order reaction, the surface will have a dramatic change upon a small change of temperature. We can use this change to calibrate temperature measurement at the surface layer.
The initial D/Ge (100) surface prepared in room temperature is disordered, consisting mixed local atomic arrangement. During laser heating, as the surface temperature increases, the surface structure became increasingly ordered; the structure is transformed to another structure. Then as surface temperature rises to ~530 K, the density of dangling bonds increases significantly. The single dangling bonds (SDs) is minority species, only 15% of that of the paired dangling bonds (PDs). As the temperature rises over 550K, Ge-strips appear on the surface, even form 2D Ge-islands. The result of laser heating process to 530 K and over 550 K didn’t discover in previous study.
Among of these thermal reactions, we can use D/Ge (100)-(2×1) thermal desorption reaction to calibrate internally the optical temperature measurement. We have found that the IR Imager’s suitable emissivity set point for the Germanium sample is 0.67 and, the error of the non-contact surface temperature measurement is within.

並列關鍵字

temperature ； deuterium ； hydrogen ； germanium(100) ； thermal desorption ； laser heat

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