Influence of Surface Morphology of Silicon Nanowire Array on Their Humidity-Sensitive Characteristics

Abstract

The paper investigates the influence of the surface morphology of an array of silicon nanowires (SNW) on their humidity-sensitive characteristics. In this work, diode-type moisture sensors based on silicon nanowires were synthesized. SNWs were synthesized by the method of metal-stimulated chemical etching, and a p–n junction was formed in the SNW array by diffusion. The surface morphology was studied by the method of atomic force microscopy. The electrical and moisture-sensitive characteristics of the humidity sensors were measured. The influence of the root mean square value (RMS) of surface roughness and the volume porosity of material on the performance of the devices was determined. In particular, it has been shown that an increase in the surface roughness of the silicon nanowire array leads to a significant increase in the response (by up to 72.5 times), as well as a decrease in the response time and the recovery time of humidity sensors amounting to 20 and 36 s, respectively. On the other hand, the reduction of the roughness RMS leads to an improvement in reversibility (up to 11.3%), short-term stability (up to 1.61%), and repeatability of the sensor signal (up to 0.45%). The importance of taking into account the relationship between the surface morphology of the array of nanowires and their humidity-sensitive characteristics for the development of high-performance nanowire-based sensors has been demonstrated.