SYNTHESIS OF NANOWIRE NETWORKS FOR CHEMICAL GAS SENSOR APPLICATIONS

1. SYNTHESIS OF NANOWIRE NETWORKS FOR CHEMICAL GAS SENSOR APPLICATIONS A.Jishiashvili Institute of Cybernetics. Georgian Technical University.

2. nm micrometer nm

4. The purpose of this work: • to synthesize the NW network using the new pyrolytic growth technology; • to study the performance of fabricated gas sensor.

6. InP core Ga2O3 shell

7. Schematic of the experimental arrangement for the growth of In2O3 nanowires Dependence of source temperature on the applied power Dependence of source temperature on time

8. In2O(g) + H2(g) = 2In + H2O(g) ΔG= - 126 kJ In2O(g) + 2H2O(g) = In2O3 + 2H2(g) ΔG= - 200kJ XRD pattern of In2O3 nanowires(a); SEM images of tapered nanowires grown at 420°C (b-d).

9. SEM images of nanowires (a-c); Energy Dispersive X-Ray pseudo-color images of nanowires grown at 420°C (e-d).

10. b a c SEM image of nanowires grown at 470ºC (a); High Resolution TEM image of VLS grown In2O3 nanowires (b) and corresponding SAE pattern.

11. Ti/Au contact layers Oxygen mediated mechanism of NH3 sensing O2+e- O–2(ads) O–2(ads)+e–2O–(ads) 2NH3+3O-(ads) N2+3H2O+3e- Fabricated In2O3 nanowire network based gas sensor

12. Variation of sensitivity with concentration of ammonia for In2O3 nanowire-based sensor at 300°C Permissible exposure limit for ammonia is 35 ppm (Occupational Safety and Health Administration) Gas sensing characteristics of In2O3 nanowires for 800 ppm of ammonia at different temperatures

13. The results of this study demonstrate that : • developed new pyrolytic technology may be successfully used for producing In2O3 nanowires; • gas sensor fabricated on the base of In2O3 nanowire network can be used for detecting 10 ppm level of ammonia.

14. Thank you