High-performance ethanol sensor based on In2O3 nanospheres grown on silicon nanoporous pillar array.

The In 2 O 3 /Si-NPA (silicon nanoporous pillar array) gas sensor featured by In 2 O 3 nanospheres coating on porous nanopillars were prepared. And the sensor exhibits an excellent ethanol sensing performance even under low gas concentrations. • A novel In 2 O 3 /Si-NPA gas sensor featured by microchannel network with large specific surface area was prepared. • The sensor shows high selectivity and response, long-term stability, short response time to low concentration of ethanol. • The high performance is attributed to the large specific surface area and massive surface active sites of In 2 O 3 /Si-NPA. At the interfaces between different materials, electronic systems with unusual electronic properties can be generated. Here, we report an In 2 O 3 /Si nanoheterostructures prepared by depositing indium grain film on silicon nanoporous pillar array (Si-NPA) by a vacuum thermal evaporation technique and a following thermal oxidation method. The composition and morphology of In 2 O 3 film on Si-NPA were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), which disclosed that the In 2 O 3 film is composed of a layer of In 2 O 3 nanospheres with massive interfaces coating on Si-NPA. The sensor based on In 2 O 3 /Si-NPA showed high selectivity to ethanol, and demonstrated a high response of 3.38 at the extremely low ethanol gas concentration of 2 ppm. The response and recovery times to 100 ppm were 3 s and 39 s, respectively. The high performance was attributed to the specific nanostructure feature of In 2 O 3 /Si-NPA sensor, large specific surface area and massive surface active sites. Moreover, the impressive features of In 2 O 3 /Si-NPA heterostructures have been discussed in detail from its geometrical and band structure. These results observed here indicate that the In 2 O 3 /Si-NPA sensor may be a promising sensing candidate for detecting low-concentration ethanol. [ABSTRACT FROM AUTHOR]