Fig. 2

Electrical characteristics and photoresponse of the Fe_0.021Sn_0.979S₂ monolayer. a Transfer and b output characteristics of Fe_0.021Sn_0.979S₂. The inset shows an optical image of one typical device and the AFM image of the corresponding sample used for fabricating the device. c Time-dependent I _sd of the transistor based on Fe_0.021Sn_0.979S₂ during the light (638 nm, 2.63 μW) switching on/off under a positive source–drain voltage, V _sd, from 1 to 3 V. d Photoresponsivity (R) as a function of light power (P) with a V _sd of 3 V