Joint Study on Hydrogen-Mediated Epitaxy

我们最近发现的氢介导外延现象，即通过氢原子终止衬底来改善生长在硅衬底上的薄膜的外延，不仅引起了关于氢与表面相互作用的基础科学的极大关注，而且还涉及到促进异质外延和形成原子突变界面的可能性。本研究的目的是为了在原子尺度上阐明氢诱导外延的机理，为半导体、金属和陶瓷等材料的新发展，以及利用原子氢引发的自组织制备量子纳米结构提供基础数据。值得特别指出的新发现如下：(1)当氢中介外延用于制备Gedelta掺杂的硅结构时，氢的存在抑制了Ge原子的表面偏析，从而改善了界面突变性。(2)当氢中介外延用于在硅衬底上生长Ge薄膜时，在Ge生长过程中动态地提供原子氢作为表面活性剂，促进了Ge的逐层生长。在氢原子引发的2D金属/Si表面相自组织为3D金属团簇的过程中，In/Si等系统中的衬底Si原子的重构结构被氢气终止冻结，表明可能发生了原子-氢致衬底Si原子的自组织，这些结果为更好地理解氢中介外延的机理奠定了基础。

Our recently discovered phenomena of "hydrogen-mediated epitaxy", in which the epitaxy of a film growing on a Silicon substrate is improved by terminating the substrate by hydrogen atoms, have received considerable attention in connection not only with fundamental science on interaction of hydrogen with surfaces, but also with the possibilities of both the promotion of heteroepitaxy and the formation of atomically abrupt interface. The purpose of this research project is to obtain fundamental data for elucidation of the mechanism of hydrogen-mediated epitaxy on atomic scale, novel development of materials such as semiconductors, metals and ceramics, and fabrication of quantum nano-structures with use of self-organization triggered by atomic hydrogen. The new findings worthy of special mention are as follows.(1)When hydrogen-mediated epitaxy was applied to fabricate a Gedelta -doped structure in Si, the surface segregation of Ge atoms was suppressed in the presence of hydrogen, resulting in improvement of the interface abruptness.(2)When hydrogen-mediated epitaxy was applied to Ge thin film growth on Si substrates dynamically supplied atomic hydrogen during Ge growth acted as a surfactant, which promoted layer-by-layer growth. Hydrogen atoms desorbed from the growth front after adsorption for some residence time, indicating a dynamical effect of hydrogen-surfactant.(3)In the self-organization of 2D metal/Si surface phase into 3D metal clusters triggered by atomic hydrogen, the reconstructed structures of substrate Si atoms were frozen by hydrogen-termination for In/Si and other systems, indicating the possible occurrence of atomic-hydrogen-induced self-organization of substrate Si atoms.These results cause the key of better understanding of mechanism of hydrogen-mediated epitaxy.