Bidirectional Current Gating in Two-Terminal VO₂/AIN/Si Heterostructure Device Using 976 nm Laser Diode.

Bidirectional current gating was realized in a vanadium dioxide (VO₂) thin film-based two-terminal heterostructure device using a near-infrared laser diode (LD) with a center wavelength of 976 nm. The VO₂ thin film used in the device fabrication was grown through pulsed laser deposition on a Si substrate with an aluminum nitride (AIN) buffer layer. The phase transition temperature of the fabricated VO₂/AIN/Si heterostructure device was ~78 °C, which is higher by ~10 °C than that of the device based on a conventional VO₂ thin film grown on a sapphire (Al₂O₃) substrate. Bidirectional current gating up to 60 mA was realized by directly irradiating the exposed thin film surface with the focused laser beam. The transient responses of the current flowing through the device were investigated for various pulse widths and repetition rates of the focused laser beam. The average switching contrast between off- and on-states was measured as ~9993. The average rise time of the current gating was ~31.5 ms with a much shorter fall time of ~4.0 ms. Our VO₂/AIN/Si heterostructure device could provide a high on-state current and fast response due to a smaller device dimension and higher phase transition temperature compared with previous implementations.