Hybrid complementary inverter based on carbon nanotube and IGZO thin-film transistors with controlled process conditions

Carbon nanotubes (CNTs) and indium-gallium-zinc oxide (IGZO) have emerged as important materials for p-type and n-type thin-film transistors (TFTs), respectively, due to their high mobility, flexibility, and low fabrication temperature. However, fabricating sophisticated macroelectronic circuits operating in complementary mode is challenging using only a single material, because implementing n-type CNT TFTs and p-type IGZO TFTs is difficult. Therefore, hybrid complementary circuits integrated with p-type CNT TFTs and n-type IGZO TFTs have been demonstrated to combine the strength of each TFT. However, limited efforts have been devoted to optimizing the circuit performance by tuning the process conditions under which the percolated CNT network channel and IGZO channel are formed. In particular, the densities of CNTs in the network channel and the amount of oxygen vacancies in the IGZO channel can be simply adjusted, which are important in determining the electrical properties of each TFT. In this work, we systematically investigated the device and circuit performance by varying such conditions; hence, we confirmed the design features of each TFT that can be optimized to enhance the hybrid complementary circuits.