Electrical oscillation generation with current-induced resistivity switching in VO₂ micro-channel devices

Figures & data

Figure 1. Optical microscope image of a D₂₀ VO₂ micro-channel device. (b) The change in VO₂ resistivity for increasing and decreasing temperatures.

Figure 2. I–V curves for devices D₁₀ (a) and D₂₀ (b) under VC mode of operation at increasing (•) or decreasing (▲) device voltage. The insets show the corresponding I–V curves at increasing or decreasing total voltage in the circuit. Measurements were performed with fixed R_ext  = 4.0 kΩ and T_S  = 64 °C for both devices. Points V_th1 and V_th2 are the threshold voltages corresponding to the forward and the reverse IMT, respectively.

Figure 3. I-V curves for devices D₁₀ (a) and D₂₀ (b) under CC mode of operation at increasing (•) or decreasing (▲) device current. Measurements were performed with fixed R_ext  = 4.0 kΩ and T_S  = 64 °C. Points V_th1 and V_th2 are the threshold voltages corresponding to the forward and the reverse IMT, respectively.

Figure 4. Electrical oscillation waveforms obtained under CC mode of operation for devices D₁₀ (a) and D₂₀ (b). Measurements were obtained at fixed I_SP = 0.8 mA, R_ext  = 1.5 kΩ and T_S  = 64 °C.

Figure 5. Electrical oscillation waveform obtained under CC mode of operation for a D₁₀ device without any external series resistance. The measurement was carried out at fixed I_SP  = 0.6 mA and T_S  = 60 °C.

Figure 6. Electrical oscillation waveforms obtained under CC mode of operation for a D₁₀ device at fixed I_SP = 1 mA, R_ext = 1.5 kΩ and T_S = 60 °C. (a) no laser illumination and (b) illuminated by a laser with P_o ≈ 455 W/cm². (c) Measured oscillation frequencies and (d) peak-to-peak amplitude voltage for a D₁₀ device at different laser power densities. The dashed straight lines in (c) and (d) are guides to the eye.

Figure 7. Nonlinear square fittings of the exponential part of the voltage build-up in the VO₂ micro-channel for one oscillation cycle for: (a) device D₁₀: I_SP  = 1 mA and I_SP  = 0.6 mA with fixed T_S  = 60 °C and R_ext  = 1.5 kΩ. The inset shows the schematic of the physical equivalent circuit for the VO₂ micro-channel devices. (b) Device D₁₀: R_ext  = 0 Ω and R_ext  = 1.5 kΩ with fixed I_SP  = 0.6 mA and T_S  = 60 °C.

Figure 8. (a) Equivalent circuit model for the VO₂ micro-channel devices. (b) Simulated and experimental waveforms for a D₁₀ device with I_SP  = 0.6 mA, R_ext = 0 Ω, and T_s = 60 °C.