Synthesis of violet phosphorus with large lateral sizes to facilitate nano-device fabrications

Violet phosphorus has been proven to be the most stable phosphorus allotrope and has attracted much attention recently. The growth of violet phosphorus with large lateral sizes is crucial to obtain good quality violet phosphorene for nanodevice fabrication. Herein, a large number of violet phosphorus plates have been produced from molten lead using an optimized method to achieve red bronze luster. The crystal structure of the as-produced violet phosphorus was determined by single-crystal X-ray diffraction to be monoclinic with the space group P2/n (13) (CSD-2160375), identical to the one from the chemical vapor transport method (CSD-1935087). The as-produced violet phosphorus plates were found to have lateral sizes of 1.30 ± 0.41 mm². The violet phosphorus plates were easily exfoliated and directly transferred to silicon substrates to facilitate building of a back-gate field-effect transistor. A hole mobility of 2.308 cm² V^-1 s^-1 was obtained from a violet phosphorus nanosheet with a thickness of 52 nm under ambient conditions. The absolute responsivity of 130 mA W^-1 with a fast response time of 27 ms was also obtained under the irradiation of a 530 nm laser.