Enhanced response characteristics of p-porous silicon (substrate)/p-TeO2 (nanowires) sensor for NO2 detection

A novel composite structure of p-porous silicon/p-TeO2 nanowires has been successfully synthesized using Te powder as source materials and porous silicon as growth substrate by thermal evaporation method. The morphological feature and crystal structure of the TeO2 nanowires grown on porous silicon were characterized by scanning electron microscopy, X-ray diffraction and transmission electron microscopy. As prepared TeO2 nanowires with diameters ranging from 100 to 200 nm and lengths up to 15 μm were covered by a distinctly snow-like over layer along whole length. Gas sensing properties of both composite structure sensor and pristine porous silicon sensor were examined at the working temperature of 26-150 °C with NO2 concentration ranging from 0.05 to 3 ppm. Next, we made a comparison of gas sensing performances between porous silicon/TeO2 nanowires and other reported TeO2 nanowires. Besides, the repeatability and selectivity of the new sensor were also tested respectively. The results revealed that the composite structure sensor exhibited high response, excellent repeatability and good selectivity to NO2 at room temperature.