nn6b08704_si_001.pdf (1.74 MB)
Two-Dimensional SnS: A Phosphorene Analogue with Strong In-Plane Electronic Anisotropy
journal contributionposted on 2017-01-20, 00:00 authored by Zhen Tian, Chenglei Guo, Mingxing Zhao, Ranran Li, Jiamin Xue
We study the anisotropic electronic properties of two-dimensional (2D) SnS, an analogue of phosphorene, grown by physical vapor transport. With transmission electron microscopy and polarized Raman spectroscopy, we identify the zigzag and armchair directions of the as-grown 2D crystals. The 2D SnS field-effect transistors with a cross-Hall-bar structure are fabricated. They show heavily hole-doped (∼1019 cm–3) conductivity with strong in-plane anisotropy. At room temperature, the mobility along the zigzag direction exceeds 20 cm2 V–1 s–1, which can be up to 1.7 times that in the armchair direction. This strong anisotropy is then explained by the effective mass ratio along the two directions and agrees well with previous theoretical predictions. Temperature-dependent carrier density determined the acceptor energy level to be ∼45 meV above the valence band maximum. This value matches a calculated defect level of 42 meV for Sn vacancies, indicating that Sn deficiency is the main cause of the p-type conductivity.
1.7 timesin-plane anisotropyzigzag directionPhosphorene AnalogueSn deficiency2 D SnS field-effect transistors42 meVas-grown 2 D crystalsRaman spectroscopyp-type conductivityTwo-Dimensional SnScmcross-Hall-bar structuremass ratioSn vacanciesdefect levelTemperature-dependent carrier densitytransmission electron microscopyvalence bandacceptor energy levelvapor transportarmchair directionsarmchair directionStrong In-Plane Electronic Anisotropyroom temperature