Hong Chengyun, Tao Ye, Nie Anmin, Zhang Minhao, Wang Nan, Li Ruiping, Huang Junquan, Huang Yongqing, Ren Xiaomin, Cheng Yingchun, Liu Xiaolong
School of New Energy, North China Electric Power University, Beijing 102206, China.
Center for High Pressure Science, State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China.
ACS Nano. 2020 Dec 22;14(12):16803-16812. doi: 10.1021/acsnano.0c05300. Epub 2020 Nov 18.
As an emerging ultrathin semiconductor material, BiOSe exhibits prominent performances in electronics, optoelectronics, ultrafast optics, However, until now, the in-plane growth of BiOSe thin films is mostly fulfilled on atomically flat mica substrates with interfacial electrostatic forces setting obstacles for BiOSe transfer to fabricate functional van der Waals heterostructures. In this work, controlled growth of inclined BiOSe ultrathin films is realized with apparently reduced interfacial contact areas upon mica flakes. Consequently, the transfer of BiOSe could be facile by overcoming weaker electrostatic interactions. From cross-sectional characterizations at the BiOSe/mica interfaces, it is found that there are no oxide buffer layers in existence for both in-plane and inclined growths, while the un-neutralized charge density is apparently decreased for inclined films. By mechanical pressing, inclined BiOSe could be transferred onto SiO/Si substrates, and back-gated BiOSe field effect transistors are fabricated, outperforming previously reported in-plane BiOSe devices transferred with the assistance of corrosive acids and adhesive polymers. Furthermore, BiOSe/graphene heterostructures are fulfilled by a probe tip to fabricate hybrid phototransistors with pristine interfaces, exhibiting highly efficient photoresponses. The results in this work demonstrate the potential of inclined BiOSe to act as a building block for prospective van der Waals heterostructures.
作为一种新兴的超薄半导体材料，BiOSe在电子学、光电子学、超快光学等领域表现出卓越的性能。然而，到目前为止，BiOSe薄膜的面内生长大多在原子级平整的云母衬底上实现，界面静电力给BiOSe转移以制造功能性范德华异质结构带来了障碍。在这项工作中，实现了倾斜BiOSe超薄薄膜的可控生长，云母片上的界面接触面积明显减小。因此，通过克服较弱的静电相互作用，BiOSe的转移变得容易。从BiOSe/云母界面的横截面表征发现，面内生长和倾斜生长都不存在氧化物缓冲层，而倾斜薄膜的未中和电荷密度明显降低。通过机械按压，倾斜的BiOSe可以转移到SiO/Si衬底上，并制造出背栅BiOSe场效应晶体管，其性能优于先前报道的在腐蚀性酸和粘性聚合物辅助下转移的面内BiOSe器件。此外，通过探针尖端实现了BiOSe/石墨烯异质结构，以制造具有原始界面的混合光电晶体管，表现出高效的光响应。这项工作的结果证明了倾斜BiOSe作为未来范德华异质结构构建块的潜力。
