Mechanism Of Trace Level H₂S Gas Sensing Using Rf Sputtered SnO₂ Thin Films With Cuo Catalytic Overlayer

H₂S gas sensing response characteristics of bare SnO₂ thin films and heterostuctures with nanolayer (10 nm) of Cu and CuO are studied. Changes in resistance values, occurring with integration of Cu and CuO nanolayers on SnO₂ is acquired real-time, and compared. Rise in sensor resistance after introduction of Cu and CuO nanolayers on SnO₂ sensing layer is understood to enhance the sensing response characteristics. Formation of space charge region between p-type CuO and n-type SnO₂ and difference in work-function values between catalyst and sensing layer are shown to govern the increased value of starting resistance. Increase in starting resistance and lowering of resistance in presence of H₂S due to spill-over of dissociated H₂S gas molecule are playing crucial role in influencing the sensing response.