发布日期:2019-11-14 17:21|浏览量:   来源:  


主讲人:严清峰副教授 (清华大学)



讲座内容简介:Few-layer phosphorene has shown a plethora of exciting properties and applications, which can be exfoliated from orthorhombic black phosphorus (BP) single crystals. Here, we report the synthesis of orthorhombic BP single crystals through chemical vapor transport (CVT) reaction based on the red phosphorus/tin/iodine (RP/Sn/I2) system. An unencapsulated field-effect transistor (FET) based on a 6 nm thick BP nanoflake exfoliated from the as-grown BP single crystal exhibited an impressive hole mobility (?p) of 1744 cm2V-1s-1and an admirable on/off current switching ratio (Ion/Ioff) of ~104. These results proved the high quality of the BP crystals synthesized by the CVT reaction method. Furthermore, we revealed that the BP nucleation and growth proceeded from the crystalline monoclinic violet or Hittorf’s phosphorus, which was accurately confirmed via a series of structural and optical experimental identifications and supported by quantum chemical studies. We thus proposed a step-by-step phase-induced nucleation and growth mechanism for the growth of BP single crystals by using CVT reaction in RP/Sn/I2 system. Tellurium (Te)-doped BP bulk single crystals were also synthesized based on CVT method. Uniform Te doping up to 0.5% atomic ratio was realized. We demonstrated the application of few-layer phosphorene in directing the self-assembly of asymmetric polystyrene-block-polymethylmethacrylate (PS-b-PMMA) block copolymer thin film and made a systematic cytotoxicity study of layered BP for potential biomedical applications.



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