Fluctuation-Enhanced Gas Sensing by Two-Dimensional Materials

The perspectives of gas sensing by flicker noise measurements have been presented for two-dimensional materials characterized by a high surface-to-volume ratio. These materials exhibit a wide range of electrical properties, from almost metallic (e.g., graphene) to semiconducting (e.g., MoS
2
, WS
2
, ZrS
3
, etc.) of various energy bandgaps. Two-dimensional materials exhibit imperfections, partially responsible for the flicker noise generated in their structures. Recent results show how these imperfections can be modulated to advance gas selectivity. Some materials exhibit photocatalytic phenomena induced by irradiation of multiple wavelengths. This effect can adjust the gas sensor to improve its selectivity and sensitivity. Low-frequency noise mechanisms in two-dimensional materials at different operating conditions will be presented, focusing on possible practical applications. The problems of noise measurements will also be enclosed.