Low-Temperature Processed Complementary Inverter With Tin-Based Transparent Oxide Semiconductors

Transparent oxide semiconductors are promising materials due to their various benefits, such as high mobility and cost-efficient production. However, oxide semiconductors fabricated using the sputtering method require an additional postannealing process at a high temperature, which hinders their fabrication on plastic substrates and application to flexible devices. In addition, one of the critical drawbacks of oxide semiconductors is the shortage of p-type materials. Tin monoxide (SnO), a p-type oxide semiconductor, has the advantages of high mobility and low-temperature production. To address the aforementioned limitations, this study investigates the simultaneous low-temperature process on tin-based oxide semiconductors; p-type SnOx and n-type amorphous indium gallium tin oxide (In:Ga:Sn = 7:1:2). By integrating two optimized thin-film transistors (TFTs) under postann-ealing temperature of 180 °C, we fabricated a tin-based oxide semiconductor complementary inverter, with a high voltage gain (98.0); a noise margin high ( ${\text {NM}_{H}}$ ) and noise margin low ( ${\text {NM}_{L}}$ ) of 13.9 (46.3% of ${V} _{\text {DD}}$ ) and 13.3 V (44.3% of ${V} _{\text {DD}}$ ) at a ${V} _{\text {DD}}$ of 30 V, respectively, were also recorded. For further investigation, we fabricated a comple- mentary inverter on a plastic substrate. The fabricated device exhibited remarkable bias stress stability with excellent electrical characteristics: ${\text {NM}_{H}}$ of 3.9 V (39.0% of ${V} _{\text {DD}}$ ), ${\text {NM}_{L}}$ of 4.5 V (45.0% of ${V} _{\text {DD}}$ ), and a high voltage gain of 114.5 at a ${V} _{\text {DD}}$ of 10 V, thus demonstrating admirable application to flexible devices.