Thin‐film circuits on plastic capable of high‐frequency signal generation have important applications in large‐area, flexible hybrid systems, enabling efficient wireless transmission of power and information. We explore oscillator circuits using zinc‐oxide thin‐film transistors (ZnO TFTs) deposited by the conformal, layer‐by‐layer growth technique of plasma‐enhanced atomic layer deposition. TFTs on three substrates—glass, 50‐µm‐thick freestanding polyimide, and 3.5‐µm‐thick spin‐cast polyimide—are evaluated to identify the best candidate for high‐frequency flexible oscillators. We find that TFTs on ultrathin plastic can endure bending to smaller radii than TFTs on commercial 50‐µm‐thick freestanding polyimide, and their superior dimensional stability furthermore allows for smaller gate resistances and device capacitances. Oscillators on ultrathin plastic with minimized parasitics achieve oscillation frequencies as high as 17 MHz, well above the cutoff frequency fT. Lastly, we observe a bending radius dependence of oscillation frequency for flexible TFT oscillators and examine how mitigating device parasitics benefits the oscillator frequency versus power consumption tradeoff.

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In this study, we examine the possibility of electrode-barrier interactions in modifying the electrical characteristics and current switching behavior of a trilayer junction with silver sulfide as the barrier layer. A series of Al–Ag2S–Ag crossbar junction is fabricated by thermal evaporation technique varying the thickness (30–110Å) of the sulfide layer. Current-voltage characteristics of the junctions are studied as a function of barrier layer thickness, which can suggest any role that electrode-barrier interaction may have in tuning their electrical behavior. To fully understand the performance of the barrier layer, structure and physical properties of Ag2S films are independently investigated. The microstructure of Ag2S films strongly depends on the deposition conditions that, in turn, affect their electrical and optical characteristics. The polarization of the lattice prevalent in Ag2S is shown to affect the charge carrier conduction in their films and dominates their electrical behavior and that of the junctions.

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