Flexible Complementary Oxide–Semiconductor-Based Circuits Employing n-Channel ZnO and p-Channel SnO Thin-Film Transistors

In this letter, we report flexible fully oxide-based complementary metal-oxide-semiconductor (CMOS) inverters and ring oscillators by the monolithic integration of flexible n-channel zinc oxide (ZnO) and p-channel tin monoxide (SnO) thin-film transistors (TFTs). Inverted-staggered bottom-gated TFTs were fabricated by a low-temperature RF-sputtering technique. The static voltage gain of a flexible oxide-TFT-based CMOS inverter with a geometric aspect ratio of 5 is ~12 at a supplied voltage (V
_DD
) of 12 V. An oscillation frequency of ~18.4 kHz is obtained from a five-stage flexible oxide-TFT-based CMOS voltage control ring oscillator at VDD of 12 V. Degradations of TFTs, inverters, and ring oscillators have been observed when a mechanical tensile strain is applied, whereas the influence of compressive strain is negligible.