Electrical characterisation of stearic acid/calix[4]amine Langmuir-Blodgett thin film

Abstract

Within this work we deposited 16 monolayers of stearic acid alternated with 15 monolayers of calix[4] amine to form a non-centrosymmetric Langmuir-Blodgett (LB) thin film onto an aluminized (50 nm coated) glass microscopic slide. Dielectric constant and dielectric loss for the film were determined using C-f and tan (delta-f) measurements. The value of the pyroelectric figure of merit was determined as 1.73 mu C m(-2) K-1. To elucidate the conduction mechanism of stearic acid/calix[4]amine LB film, DC current-voltage measurements between -4 and +4 V were carried out. The I(V) behaviour shows a symmetrical and highly non-linear behaviour. Analysis of this behaviour of the stearic acid/calix[4]amine LB film showed a conductivity value of 1.12 x 10(-13) S m(-1) for ohmic region. The exponential part of I(V) dependence obeyed the Schottky conduction mechanism with a barrier height of 1.67 eV. This LB film structure shows a typical insulating behaviour for low voltage values and the Schottky effect becomes dominant when the voltage increases. The frequency dependence of conductivity shows a power law relationship between conductance and frequency.