Design and engineering of Mn conical sculptured thin films as both electrodes for a gas sensor: ionization and field emission studies

Paschen's law and deviation from Paschen's law are studied in a face to face gas sensor based on Mn helical sculptured thin films with conical shape as cathode and anode electrodes. The sensor's performance was investigated at dynamic pressures ranging from 0.1 to 1000 mbar and 3 to 200 mu m gaps between the two electrodes and for nitrogen, air and carbon monoxide gases. Results showed that at distances more than 10 mu m the Paschen's law is satisfied but at lower than 10 mu m distances between the two electrodes and pressures more than 250 mbar deviations occur from the Paschen's law. Selectivity results of the sensor showed that under all conditions studied in this work and for all gases there is a good resolution between the results and this enhances with gas pressure. Comparison of the results of the present sensor with those reported in the literature showed higher sensitivity of the present work for different gases investigated.