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 WS 2 /Bi 2 Se 3 vertical heterojunctions were successfully modulated. High-quality WS 2 /Bi 2 Se 3 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 WS 2 /Bi 2 Se 3 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.
The poor air stability hinders the practical application of most 2D materials. P‐type 2D ZnTe has drawn widespread attention, thanks to its wide direct bandgap and outstanding environmental stability. However, the controllable synthesis of ultrathin 2D ZnTe remains a huge challenge due to the intrinsic unlayered crystal structure. Here, p‐type 2D ultrathin ZnTe flakes are controllably synthesized by using space‐confined physical vapor deposition. In situ temperature‐dependent Raman and electronical measurements show the thermal stability up to 420 K and outstanding air stability even under humidity of 95%. The ZnTe flakes‐based photodetector demonstrates the broadband response varying from the visible to near infrared region, responsivity of 18.3 A W‐1 and detectivity (D*) of 2.89 × 109 Jones under 405 nm illumination, implying promising potential application in electronics and optoelectronics worked in harsh environment.
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