Low-temperature highly selective and sensitive NO2 gas sensors using CdTe-functionalized ZnO filled porous Si hybrid hierarchical nanostructured thin films

Abstract

In this report, we present improved NO2 gas sensing properties based on CdTe-functionalized ZnO filled porous Si (PSi) hybrid hierarchical nanostructured thin films (CdTe/ZnO@PSi). The CdTe and ZnO nanostructured thin films were grown on the PSi substrate using a scalable magnetron sputtering technique. The PSi substrate was prepared using the electrochemical anodization method. The proposed CdTe/ZnO@PSi sensor was characterized in terms of structural, morphological, and compositional properties. The sensing performance and corresponding mechanism of NO2 gas sensor based on CdTe/ZnO@PSi were described comprehensively. In order to compare, the sensing characteristics of both CdTe/ZnO@PSi and pristine ZnO@PSi thin film sensors were tested in different temperature range varied from 30 °C to 180 °C for 1 ppm concentration of NO2 gas. We found that CdTe/ZnO@PSi sensor displays enhanced NO2 sensing characteristics (∼3.5-fold greater sensor response ∼19.82 %, fast response/recovery time ∼13 s/54 s) at the relatively low working temperature of 90 °C towards 1 ppm NO2 gas in comparison to the pristine ZnO@PSi sensor (sensor response ∼5.72 % and response/recovery time ∼41 s/124 s at an operating temperature of 150 °C). Further, the fabricated NO2 gas sensor demonstrated excellent reversibility and good stability, and enabling CdTe/ZnO@PSi a promising candidate for its practical use in IoT sensing devices.