Abstract

Modern telecommunication technologies, involved in the current 5G and upcoming the 6G telecommunication frequency ranges, rely on devices operating in the radio frequency spectrum of 0.3-100 GHz and 6-1000 GHz, respectively. Innovative fabrication methods and device designs are getting increasing attention with the goal of deploying them in new applications in order to meet the demanding performance requirements for the market. However, balancing fabrication complexity, manufacturing costs and performance presents formidable technical challenges for the industry. In this work there is a discussion about newly developed nanopatterning method called adhesion lithography to create coplanar zinc oxide Schottky diodes and logic circuits. These Schottky diodes are easy to fabricate, providing high current rectification (≈10⁵) with low reverse currents (≈80 pA) and a high cut-off frequencies of over 25 GHz. By integrating ZnO Schottky diodes on a wafer scale, logic circuits like AND and OR gates were successfully implemented. The potential for more complex monolithic circuits was shown with the development of a Half-Adder. This study presents an alternative manufacturing method for large-area radio frequency electronics and sets the foundation for diode-based circuit development for diode logic and rectifying applications.

Additionally, the human-machine interface hardware keeps becoming more common and more useful, which implies that better sensors are required to detect signals from various stimuli. Humidity sensors get attention for applications across various sectors, depending on moisture absorbing materials, which can take long recovery times, slowing their transient response and limiting their applications. This technical challenge is addressed by combining nanogap electrode architectures with albumen biopolymer as moisture-absorbing component. The resulting sensor is low-cost, highly responsive and selective to humidity, operating within a relative humidity range of 10-70% RH. The sensors show little or no response to various interfering species, keeping high responsivity of >1.15×10⁴ at room temperature. The nanometer range of nanogap structures enables fast temporal response, with rise and fall times of ~10 and ~28 ms, respectively, making the devices the fastest humidity sensors reported to date based on biomaterials. By leveraging these features, we demonstrate non-contact switching and real-time respiratory cycle monitoring suitable for diagnosing chronic diseases.