Theoretical Research Of Site-selective Substitutional Doping With Atomic Precision On Metal Surface By Single-atom Manipulation

As the size of devices decreases to nano or even to atomic scale, both the number and location of individual atoms or defects could affect their functionality and performance. For Si-based quantum devices, the single-ion implantation technique combining with the various single-ion detection schemes has been widely used for the deterministic doping, in which numbers and placements of ions are well controlled. However, owing to ion straggling, the dopant placement accuracy has an inherent limitation of about ten nanometers. On improving the positioning accuracy of the single dopant atom, scanning tunneling microscope(STM)-based hydrogen lithography was developed. This method possesses a near-atomic precision as a result of incorporating single-atom manipulation and hydrogen lithography. As we know, single-atom manipulation by STM was proved to be precise in atomic scale, which benefits from the direct handle of individual atoms at specific site. Hence it owns a potential to position single dopant atom or fabricate nanodevices on atomic precision. It is of great interest to combine single-atom manipulation with single-atom doping.In the present work, we consider stepped Al(111) surface and theoretically explore a single-atom substitutional doping. With the atomic manipulation an individual atom at the step of Al(111) surface is extracted first by the tip, and then single Ag or Au dopant is positioned to the original site. Based on the first-principles simulation, the details of the doping process are given and its reliability is discussed.Chapter 1 provides historical background and new developments of single atom manipulation and single-atom doping. Also provide the motivation of our study.Chapter 2 describes briefly the theoretical foundations and methods used in the study which mainly is first-principles simulation.Chapter 3 describes the doping process in detail, and the principle of the doping process is also provided.The last chapter presents a summary of this thesis and some prospects for thefuture investigations.