Development of velicity selector for metal atom and its application in thermal engineering

为了研究入射原子平动能对薄膜凝聚过程的控制，用Hostettler-Bernstien速度选择器真空沉积方法在(001)NaC l、(001)MgO和玻璃上沉积了Bi2Te3薄膜和BiTe薄膜，通过测量薄膜的热电势和用透射电子显微镜观察，研究了薄膜的晶体结构。薄膜不仅受衬底温度的影响，而且受原子入射速度的影响也很大。用速度选择器在一定的衬底温度下制备薄膜，可以得到良好的热电元件。然而，由于很难用速度选择器在较高的入射频率下进行实验，所以我们无法阐明入射频率对沉积过程的影响。通过分子动力学模拟研究了入射速度、衬底温度和入射频率对Kr原子在Ar衬底上沉积过程中凝聚现象的影响。衬底温度和入射原子的速度影响沉积原子的成核和再蒸发的生长速度。此外，这些因素对模拟过程中沉积薄膜的结构也有影响。在较高的衬底温度下，薄膜的结构被破坏，但在一定的衬底温度、较小的入射速度和较低的入射频率下，晶体在衬底上生长具有特征的各向异性。

To study the control of the thin film condensation process with the translational energy of incident atom, crystalline structures of Bi_2Te_3 films and Bi, Te films, which are deposited on (001) NaCl, (001) MgO and glass by the vacuum deposition method with a Hostettler-Bernstien velocity selector, have been investigated by measurement thermoelectric power of film and the observation by a transmission electron microscopy. Thin films are affected by not only substrate temperature but also velocity of incident atoms greatly. We could obtain good thermoelectric element when we made films at a certain substrate temperature with velocity selector. However we could not clarify the effect of incident frequency on the deposition process, because it is difficult to conduct experiments at the high incident frequency with a velocity selector. Thus a molecular dynamics simulation has been performed to investigate the effects of incident velocity, substrate temperature and frequency of incident on the condensation phenomena in the deposition process of Kr atoms on Ar substrate. Substrate temperature and velocity of incident atom are affect the growth rate of nucleation and reevaporation of deposited atoms. Further those affect the structure of deposited film in the simulation. At high substrate temperature structure of thin film is broken, however at a certain substrate temperature, small incident velocity and low incident frequency, crystals grow with characteristic anisotropy on the substrate.