Advancements and hurdles in contact engineering for miniaturized sub-micrometer oxide semiconductor devices

With conventional silicon-based devices approaching their physical scaling limits, alternative channel materials, such as transition metal dichalcogenides and oxide semiconductors (OSs), have emerged as promising candidates for extending Moore's law and advancing performance, power efficiency, area scaling, and cost-effectiveness. Among these, OSs stand out as particularly promising, having already been established as the industry standard for high-end active-matrix organic light-emitting diodes due to their moderate mobility, extremely low off-current, steep subthreshold swing, excellent uniformity, and compatibility with low-temperature fabrication processes. However, to enable the deployment of OSs in more demanding applications, such as 3D dynamic random-access memory and other advanced electronic systems, further improvements are necessary, particularly in terms of enhancing on-current and hydrogen stability and reducing contact resistance (RC). In this work, we review strategies to optimize electrical contact properties to improve the device performance of OSs and examine the underlying mechanism of RC from a device physics perspective.