160 GHz Schottky Diodes from Solution-Processed IGZO

Traditional radio frequency (RF) electronics rely on discrete devices, such as diodes, transistors, capacitors, and antennas capable of operating in the GHz frequency domain. Unfortunately, integrating these components to realize large-area RF electronics presents formidable challenges. Herein, we demonstrate wafer-scale, solution-processed indium-gallium-zinc-oxide (IGZO) Schottky diodes with a cut-off frequency exceeding 160 GHz. The diodes feature planar asymmetric self-aligned nanogap electrodes patterned via adhesion lithography (a-Lith) and a flash lamp annealed solution-processed IGZO as the semiconducting layer. An enabling feature of the devices is the Ohmic contact facilitated by an ultra-thin (10 nm) ZnO layer deposited atop the aluminum electrode without increasing the manufacturing complexity. The ZnO interlayer shifts the work function of the aluminum electrode closer to the conduction band of IGZO, reducing the injection barrier and improving electron injection. The ensuing diodes show reduced turn-on voltage (≈0.08 V), higher on-current, high rectification ratio (≈10⁵), and ultra-low junction capacitance (<15 pF). RF rectifier circuits made of these IGZO diodes yield a maximum output DC voltage of 0.74 V with an extrinsic cut-off frequency exceeding 160 GHz, making them the fastest large-area diodes reported to date. Our technology offers scalable manufacturing with unprecedented performance and creates new opportunities for emerging applications.