采用KrF准分子激光辐照4H-SiC制备石墨烯层,从4H-SiC晶面取向对石墨烯生长质量影响的角度开展研究工作,分析激光能量密度、脉冲数及晶面取向对石墨烯质量的影响。当激光能量密度为1.06 J/cm 2,脉冲数为8000时,4H-SiC样品极性Si(0001)面和非极性a(11?20)面上生长的石墨烯质量均达到最好。石墨烯与4H-SiC衬底极性Si(0001)面之间存在缓冲层,为石墨烯的生长提供了模板,得到的石墨烯更为有序,缺陷态更少;而非极性a(11?20)面上生成的石墨烯与衬底之间未生成缓冲层,生长的石墨烯层较为无序,对激光参数的变化更为敏感。

In this paper, a KrF excimer laser is used to decompose 4H-SiC substrates to prepare graphene layers. The research is focused on the influence of the crystal orientation of 4H-SiC on the quality of the graphene produced. The effects of laser energy density, pulse number, and crystal orientation on graphene quality are analyzed. With a laser energy density of 1.06 J/cm 2 and a pulse number of 8000 shots, the graphene obtained on the polar Si-plane (0001) and on the non-polar a-plane (11?20) of the 4H-SiC sample are both of the best quality. We find that a buffer layer that provides a template for the growth of graphene is formed between Si-plane (0001) and 4H-SiC substrate. The graphene obtained from the buffer layer is consequently more ordered and has fewer defects. In contrast, there is no buffer layer between the photo-generated graphene on a-plane (11?20) and 4H-SiC substrate, which results in the generated graphene being disordered and more sensitive to the laser parameters.