Facile preparation of Silicon/ZnO thin film heterostructures and ultrasensitive toxic gas sensing at room temperature: Substrate dependence on specificity.

Facile preparation of Silicon/ZnO thin film heterostructures and ultrasensitive toxic gas sensing at room temperature: Substrate dependence on specificity. Anal Chim Acta. 2018 Dec 18;1039:82-90 Authors: Betty CA, Sehra K, Barick KC, Choudhury S Abstract Two types of silicon-Zinc oxide (ZnO) heterostructures were prepared simply by depositing (drop casting) chemically prepared ZnO nanoparticles onto single crystalline (p-type) silicon substrates (Si) as well as electrochemically prepared p-type porous silicon (PS). ZnO nanoparticles and PS/ZnO structures were characterized structurally by various techniques. By depositing in-plane gold contacts on the heterostructures, gas sensors were fabricated and characterized electrochemically by dc and ac impedance measurements. The PS/ZnO sensors showed specific response at room temperature for NO2 with increase in current and no significant response for other reducing and oxidizing gases. The sensor is sensitive to 200 ppb NO2 at 25 °C with 35% change in current and 50 s response time. Temperature dependent studies of sensor in the range of 25-100 °C have shown maximum sensitivity at 40 °C (50% change for 200 ppb) with decreasing sensitivity thereafter (23% change at 60 °C), indicating the suitability of the sensor till 60 °C. Alternatively Si/ZnO heterostructures showed maximum response with NO2, along with lesser specific responses for SO2 and NH3. Detailed multifrequen...
Source: Analytica Chimica Acta - Category: Chemistry Authors: Tags: Anal Chim Acta Source Type: research