Voltage Bias Effect on Light-Induced Bistable Switching in Two-Terminal Device Based on VO₂ Thin Films

In this manuscript, we experimentally investigate the effect of DC voltage bias on laser-induced bistable switching behavior in a two-terminal device based on vanadium dioxide (VO₂) thin films. To explore this phenomenon, a DC voltage source was connected in series with the device and a resistor to form a closed-loop circuit. The static and transient responses of the circuit current (I) were measured as the optical power (PL) of a ~1.55μm laser beam, incident on the VO₂ film, was varied under different bias voltages (V_S). In the static response, current I exhibited hysteresis with respect to PL, but only within a narrow range of V_S (6 ~ 9 V). Within this range, decreasing V_S shifted the hysteresis loop toward higher PL values and narrowed its width, while increasing V_S had the opposite effect. Outside this voltage range (V_S < 6 V or V_S > 9 V), the hysteresis behavior disappeared. At low V_S, the device showed no switching, and at high V_S, the switching became irreversible rather than bistable. In the transient response, clear laser-induced bistable switching was observed only in a narrower V_S range (8 ~ 9 V), suggesting that dynamic bistability requires more stringent bias conditions compared to static hysteresis.