【作者】 王得勇；

【导师】 刘杰； 薛其坤；

【作者基本信息】 山东师范大学 ， 光学， 2004， 硕士

【摘要】 本文的工作主要是利用分子束外延技术，扫描隧道显微镜和角分辨光电子能谱研究铝薄膜的电子生长，褪火对铅薄膜的影响，铅薄膜中电子的量子阱态，以及利用STM对原子进行巨量操纵。 在利用两步生长法制备原子量级上平的铝薄膜的研究中，我们首先利用RHEED研究了低温在Si(lll)-7×7上沉积铝薄膜的演化过程，利用STM得到此系统铝薄膜的临界厚度为4ML，通过分析指出薄膜中电子的量子阱态对薄膜的稳定性起很大的作用，利用传输运动和漏斗效应讨论了薄膜生长的动力学途径，利用电子生长模型从能量的角度解释了临界厚度。从生长的过程，我们利用传输运动和漏斗效应解释了薄膜的临界厚度，传输运动和漏斗效应相互竞争使得当覆盖度达到4ML时薄膜形成。从电子生长的角度看，薄膜中电子的量子阱态，界面处的电荷转移，界面诱导的弗里德尔振荡三个因素决定薄膜的稳定性，于是薄膜超过某一厚度后稳定，随后稳定厚度的薄膜以一定的周期振荡，超过此厚度稳定薄膜的厚度为临界厚度，振荡中相对稳定的厚度是幻数厚度。我们实验得到，铝硅系统的临界厚度为4ML，此结果与UPS的结果正好相符。 在Si(lll)-7×7上生长铅的实验中，我们研究了褪火和覆盖度对薄膜稳定性及生长模式的影响。通过研究我们发现，随覆盖度的变化，褪火到室温的铅薄膜稳定性分为三个区域：低于6ML铅，在145K低温不能形成薄膜；6ML-10ML的铅，在145K低温形成铅薄膜，褪火到室温铅薄膜变成岛；覆盖度大于10ML的铅薄膜褪火到室温稳定，不会变成岛。随覆盖度的变化，褪火到室温的铅薄膜的生长模式也分为三个区域：覆盖度小于10ML为SK生长模式；10ML-20ML铅薄膜的模型解释了我们的结果，并改进了电子生长模型。在利用UPS研究薄膜粗糙度对量子阱态峰型的影响的实验中，我们发现：薄膜粗糙，峰型宽；薄膜平整，峰型锐利。 在铅岛上进行原子操纵实验中，我们利用STM及电子生长的动力学机制成功将生长控制在原子层的量级上，将单层或双层的原子排列在我们提前生长的铅岛上。在对原子进行操纵时，体现了电子能量最小和表面自由能最小之间的振荡， 摘要活像以单摆势能与动能之间的转化，我们把这种现象叫做自由能单摆。利用这种原子操纵的办法，我们还可以按自己的意愿将己生长的岛排成我们想要的图案。 总之，我们得到原子量级上平的铝薄膜，并且其临界厚度为4ML;铅在51(111)一7x7上生长的实验中，我们发现温度不同，临界厚度的变化，从而改进了电子生长模型，利用STM和U咫得出:薄膜粗糙度对薄膜中电子量子阱态峰型的影响。原子操纵实验中，我们成功的将巨量的原子排列在铅岛上，实现了原子的巨量操纵。更多还原

【Abstract】 In this dissertation, electron growth of the aluminum film, the evolvement of the lead film when annealed from LT to RT and the electron states in lead film were studied using MBE STM UPS. In addition, manipulate many atoms also was studied by STM.In the experiment of making atomically flat aluminum film using the two step growth, we firstly studied the evolvement of the aluminum film deposited on Si (111) -7 7 surface at LT by RHEED, and get the critical thickness of the aluminum film(4ML). We explain this phenomenon using the electron growth mode from the energy and using transient mobility and downward funneling from the process of film forming. The competition of the transition mobility and the downward funneling make aluminum film form at 4ML. The energy of the electrons in the film is minimum when film is more 4ML according to the electron growth mode, then the critical thickness of the aluminum film in Al/Si system is 4ML. Our results unambiguously explain why QWS could be observed only for the films with 4ML or over 4ML aluminum in this system.In the experiment of depositing lead film on Si (111) - 7 7, we studied the effect of annealing and the coverage to the stability and the growth mode of the film and found that when film get thicker, the stability of the film is different: When thethickness of the film is lower than 6ML, film can not form at LT; 6ML-10ML, film form at LT, but get islands when annealed to RT; more 10ML, film is stable during annealing. In addition, the growth mode of the film annealed to RT is different, thinner than 10ML, film can not form at RT; 10ML-20ML, the growth mode is two layers by two layers; more 20ML, the growth mode is layer by layer mode. We improved electron growth mode and explain this phenomenon. The total energy of the film not only include quantum well states and electron spilling, but also include the contribution of the temperature, when we plus the contribution of the temperature in total energy, the critical thickness of the film will change, then the critical thickness of the lead film we deposit is 6ML at 145K and 10ML at RT. In addition, we studied the roughness of the film is how to effect the peak of the QWS and found that when film is rough, the peak is wide, and when film is flat, the peak is sharp.Free energy cost from surface steps provides the usual driving force for smoothening metallic film on a substrate. For very thin films, quantum size effect (QSE) can become dominant in the evolution of the film geometry, leading to distinctive consequences such as the formation of films only with specific thicknesses. In this experiment we exploit the competition between these two effects to manipulate mass transport involving millions of lead atoms on Si(111)-77 surface and build up pre-designed nanostructures with atomic-layer precision using a scanning tunneling microscope (STM). Like a nanoscale free energy pendulum, the system studied exhibits an intriguing morphological dynamics, swinging between two extreme states favored by each of these effects. Using this method we also can getisland pattern that we want.In summary, we get atomically flat aluminum film and the critical thickness (4ML), in lead film deposited on Si, we improve electron growth mode and get the critical thickness of the lead film at 145K and RT, in addition, using STM and UPS, we get when film is rough, the QWS in photoemission spectroscopy is wide, and when film is flat, sharp. By STM and kinetic pathway, we successfully manipulate mass atoms on lead islands with atomically layer precision.更多还原