Giant Resistance Switching Ratio Exceeding 106 through a Reversible 2D–3D Structural Phase Transition in Nonequilibrium (Pb1– x Sn x )Se Thin Films

Control and switching of electrical resistance in semiconductors are important for high-performance electronic devices. Here, we realize giant resistance switching in nonequilibrium (Pb1–xSnx)Se films through a reversible structural transition between three-dimensional (3D) rock-salt (RS)-type and two-dimensional (2D) GeS-type phases. The solid-solution films were fabricated by reactive solid-phase epitaxy of SnSe/PbSe bilayers followed by rapid thermal quenching. Se-flux annealing of the PbSe template suppressed Pb precipitation, enabling chemically homogeneous, single-phase nonequilibrium RS-type films up to x = 0.58. Increasing the Sn content from x = 0.43 to 0.58 systematically increased the 2D–3D structural transition temperature and enhanced the resistance switching ratio to 4.9 × 106, far exceeding those of representative transition-metal oxide thin films (∼102–104). The giant resistance switching originates from the nearly complete transformation (∼98%) of the conductive 3D phase into the high-resistance 2D phase. These results establish crystal-dimensionality switching as a promising new mechanism for high-performance electronic switching devices.