Semiconductor Nanowire Arrays for High-Performance Miniaturized Chemical Sensing

Chemiresistive sensing is one of the most promising technologies for portable and miniaturized chemical sensing, with applications ranging from air quality monitoring to explosive detection and medical diagnostics. Recently, there have been growing efforts in developing microchip based chemical sensors operating at room temperature with high sensitivity, selectivity, spatial and temporal resolution, long-term stability, and cost-effectiveness. Here, the engineering of highly performing miniaturized gas sensors consisting of chemiresistive vertical indium phosphide nanowire (NW) arrays is reported for the first time, and their potential for the selective detection of nitrogen dioxide (NO₂), a major air pollutant, is demonstrated. By carefully engineering the NW geometry (i.e., diameter and pitch), a superior sensing performance than those previously reported semiconductor-based NO₂ sensors is achieved, obtaining a limit of detection of 3.1 ppb at room temperature, with outstanding selectivity, and long-term stability. Kinetic analysis and electrical simulation further reveal the array geometry correlated sensing mechanism, providing insights for the design of future NW array-based devices. These findings indicate that, owing to their unique nanoscale structures, material properties, and CMOS compatible manufacture processes, III-V compound semiconductor NW arrays present a new and promising chemical sensing platform for development of future high performance, miniaturized on-chip sensing system.