Reversible transition between bipolar resistive switching and threshold switching in 2D layered III-VI semiconductor GaSe

Recently, two-dimensional (2D) layered materials have emerged as promising candidates for resistive switching (RS) devices. However, challenges in controllable conversion of RS types in such 2D materials still remain. Here, we report the experimental realization of reversible transition between non-volatile bipolar resistive switching (BRS) and volatile threshold switching (TS) in 2D layered III-VI semiconductor gallium selenide (GaSe) nanosheets through appropriately setting the compliance current (Icc). Under a relatively high Icc value of 1 mA, the device shows non-volatile BRS performance with a high ON/OFF ratio of nearly 104, a long retention time of 12 000 s, and a high endurance of 1200 switching cycles. Furthermore, under a relatively low Icc (lower than 10 μA), the volatile TS behaviors can be observed. For the former, the large Icc can generate stable conductive filaments (CFs) of Ga vacancy. Thus, the breakage of the stable CFs needs a high reverse voltage to re-align the Ga vacancy. For the latter, the low Icc generated unstable CFs can be broken by the current induced Joule heat. This study establishes the feasibility of integrating different RS types in 2D layered semiconductor nanosheets and understanding the underlying physical mechanism of different RS types in the 2D platform.