Capacitance and resistance of SnO2 thick film gas sensors

M. PONCE; R. PARRA; M. CASTRO; C. ALDAO

Toledo

Congreso; Electroceramics X; 2006

CSIC - Sociedad Española de Cerámica y Vidrio

The film resistance is broadly used to characterize a sensor. Studies of capacitance and resistance responses of SnO2 thick films after being exposed to an air atmosphere were carried out. It was determined that adsorption of oxygen at the grain surface affects the resistance and electrical capacitance of the sensor. Schottky-type potential barriers at the grain boundaries were assumed to analyze the sample resistance. The presence of deep bulk traps were found to play an important role in these systems. Thermionic and tunnelling contributions to electrical conduction have been considered to explain the electrical behaviour of un-doped SnO2 samples. The estimated barrier height and donor concentration values were employed to establish a discussion on the main conduction modes that rule the behaviour of tin oxide sensors in presence of different gases atmospheres.