posted on 2021-03-26, 16:38authored byYihong She, Zhen Wu, Shengdong You, Quan Du, Xiaohong Chu, Lijuan Niu, Changchun Ding, Kenan Zhang, Lijie Zhang, Shaoming Huang
Two-dimensional
(2D) heterojunctions have attracted great attention
due to their excellent optoelectronic properties. Until now, precisely
controlling the nucleation density and stacking area of 2D heterojunctions
has been of critical importance but still a huge challenge. It hampers
the progress of controlled growth of 2D heterojunctions for optoelectronic
devices because the potential relation between numerous growth parameters
and nucleation density is always poorly understood. Herein, by cooperatively
controlling three parameters (substrate temperature, gas flow rate,
and precursor concentration) in modified vapor deposition growth,
the nucleation density and stacking area of WS2/Bi2Se3 vertical heterojunctions were successfully
modulated. High-quality WS2/Bi2Se3 vertical heterojunctions with various stacking areas were effectively
grown from single and multiple nucleation sites. Moreover, the potential
nucleation mechanism and efficient charge transfer of WS2/Bi2Se3 vertical heterojunctions were systematically
studied by utilizing the density functional theory and photoluminescence
spectra. This modified vapor deposition strategy and the proposed
mechanism are helpful in controlling the nucleation density and stacking
area of other heterojunctions, which plays a key role in the preparation
of electronic and optoelectronic nanodevices.