Inkjet‐Printed Indium Oxide/Carbon Nanotube Heterojunctions for Gate‐Tunable Diodes

van der Waals heterojunctions composed of dissimilar materials enable fabrication of gate‐tunable diodes showing negative transconductance characteristics. Such devices show great potential for implementation of multi‐valued logic circuits. In order to integrate such circuits, p–n heterojunctions should be reliably created by using scalable and cost‐effective methods. Gate‐tunable diodes made of p–n heterojunctions are constructed from the hybrid material combination of inkjet‐printed indium oxide and single‐walled carbon nanotubes. Inkjet printing of p–n heterojunctions in which semiconductors are partially overlapped is enabled by modification of surface conditions using plasma treatment. The resulting devices, whose p–n junctions as well as electrodes are solely formed by inkjet printing, exhibit anti‐ambipolar behavior with negative transconductance. Forward currents of these devices can be modulated by varying the gate bias.