Electrical properties of sprayed tinoxide coatings

Tin oxide layers have been produced by pyrolysis using solutions based on dibutyltin oxide and tributyltin trifluoroacetate. From measurements of the Hall coefficient and the resistivity the mobility and free electron concentration have been determined in the temperature range from 80 to 600 K. From the measurements of the free electron concentration tt is found that the Fermi energy is proportional to the free electron concentration to the power 2/3, characteristics for degenerate electron statistics. If the mobility of a layer is about 4 × 10-3 m2 V-1 s-1 it can be described by the combined effect of neutral and ionized impurities and lattice vibrations, the latter causing a decrease in the mobility with increasing temperature. If the mobility is about 10-3 m2 V-1 s-1 or lower it is mited also by grain boundary scattering. It is shown that the influence of grain boundaries cannot be described by the so-called Petriz equation. With respect to spectral selectivity tributyltin trifluoroacetate gives the best results with mobilities of the order of 5 × 10-3 m2 V-1 s-1 and carrier concentrations of about 2.5 × 1026 m-3.