Selenium-doped black phosphorus for high-responsivity 2D photodetectors

The growth of centimeter-scale selenium (Se)-doped BP crystals with controllable doping contents by mineralizer-assisted gas-phase transformation method were reported. The Se-doped BP crystals were synthesized by mineralizer-assisted gas-phase transformation method. Relatively low-cost precursors including red phosphorus, Sn,SnI₄, and Se were used for the synthesis under mild condition. The high crystallinity of the synthesized bulk crystal was well confirmed from X-ray diffraction (XRD) measurements. The microstructure and chemical composition of the Se-doped BP crystal were thoroughly probed by TEM, selected area electron diffraction (SAED), and energy-dispersive X-ray spectrum (EDS). The synthesized Se-doped BP exhibits reliable electrical characteristics with a high on/off current ratios. Significantly, the success of Se dope in BP introduces great improvement of photoelectrical properties when applied into 2D photodetectors. The responsivity of the BP devices increased remarkably accompanied with EQE improved from 149% to 2993% when the Se dope content increased to 1.6 wt%, which is over 20-fold enhancement than the pristine BP.