Surface and interface control in the epitaxial growth of boride thin films

成功地建立了一套独特的超高真空化学气相外延系统，该系统既能防止氧进入渗硼膜，又能对生长进行实时监测。在硅、蓝宝石和氮化镓衬底上外延生长了二硼化锆薄膜。来自衬底的表面分离元素在生长过程中被观察到为不同的表面重构，被发现是导致表面反应的原因。在优化的条件下，生长在蓝宝石衬底上的薄膜在稳定的界面结构的驱动下具有单晶性，而在硅衬底上生长的薄膜由于界面竞争而含有一些错误取向的微晶。

A unique ultrahigh vacuum chemical vapor epitaxy system, which prevents oxygen incorporation into boride films and also has capability of in-situ growth monitoring, was successfully built. The epitaxial growth of zirconium diboride thin films was carried out on silicon, sapphire, and gallium nitride. Surface segregating elements originating from the substrates, which were observed as different surface reconstructions during the growth, were found to be responsible for the reaction at the surface. Single-crystallinity was confirmed for the films grown on sapphire substrates under optimized conditions, driven by a stable interface structure, while the films grown on silicon contained some misoriented crystallites due to competing interfaces.