Abstract:

Two-dimensional (2D) materials are atomically flat and can be stacked into van der Waals heterostructures, as well as contain abundant physical phenomena and excellent electrical properties. The study of phase transition behavior of 2D materials has been the frontier of condensed matter physics and materials science. In our study, the stage-controlled phase transition induced by thermal-driven metal diffusion in black phosphorus (BP) is realized for the first time. Through thermal annealing treatment of the BP-In interface, the phase transition phenomenon from BP pure phase to BP/InP mixed phase and then to InP pure phase is observed. Combined with the characterization techniques of transmission electron microscopy and Raman spectroscopy, the mechanism responsible for phase transition is deeply analyzed, revealing that the thermal-driven metal diffusion behavior in BP-In is the main inducement of phase transition. The two key threshold temperatures (initiation of phase transition and transformation of pure phase) during the stepwise phase transition are obtained by manipulating the two degrees of freedom (temperature and time) which affect the energy supply in the thermal driving, where are 300 and 350 °C , respectively. This study provides more possibilities for expanding the applications of BP-based electronic and optoelectronic devices. 

Key words: black phosphorus(BP), metal diffusion, phase transition, transmission electron microscopy, Raman spectrum