Atomic-Scale Mapping of Layer-by-Layer Hydrogen Etching and Passivation of SiC(0001) Substrates

详细信息    查看全文

• 作者：Stefan Glass ; Felix Reis ; Maximilian Bauernfeind ; Julian Aulbach ; Markus R. Scholz ; Florian Adler ; Lenart Dudy ; Gang Li ; Ralph Claessen ; Jörg Schäfer
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：May 19, 2016
• 年：2016
• 卷：120
• 期：19
• 页码：10361-10367
• 全文大小：504K
• 年卷期：0
• ISSN：1932-7455

文摘

Preparation of SiC(0001) substrates is of high relevance to graphene growth. Yet, if only a smooth surface could be achieved, heteroepitaxy of many other two-dimensional materials comes into reach. Here we report a novel approach to hydrogen etching of SiC, based on stepwise ultrapure H exposure with slow substrate cooling rates. For the first time, the atomic evolution of the surface structure is witnessed by scanning tunneling microscopy. A detailed picture of the gas phase chemistry emerges, such as a zipper-like material desorption at step edges. The Si–C sheets are removed in layer-by-layer fashion, leading to large terraces with straight rims. The process ultimately results in an atomically smooth surface with complete H-passivation, with no detectable defect states in photoemission. The degree of perfection achieved suggests the use of this substrate as a versatile nanostructure template.