Charge carrier transport and noise in polymer based thick films

conference paper

English

We have studied thick film layers made from different polymer vehicles and three types of conducting particles – silver, carbon, graphite, and their mixture. We proposed the point contact model for the charge carrier transport in the polymer based thick film structures. The model is based on the assumption, that the charge transport is due to the electrons thermally emitted from a metallic grain and that their transfer to another grain has a main component given by ballistic transport [1] and tunneling [2] through the barrier between these two particles. Main noise and non-linearity sources in polymer based thick film layer are considered to be the contacts between conducting grains. On the basis of our model the sheet resistance and effective number of electrons acting as mobility fluctuators in one point contact can be calculated. From the low frequency noise measurements we can estimate the number of point contacts in the thick film resistive layer. The influence of the polymer vehicle and thermal treatment on the thick film structure can be characterized by noise and nonlinearity measurements. Polymer vehicle with better wettability creates the thin film layer between the conducting grains and this leads to the increase of both resistance and noise spectral density. During the thermal treatment the conductivity of the resistive layer is changed due to the change of number of contacts between conducting grains – the distance between conducting grains varies as a result of polymer matrix dilatation. Good correlation between noise and non-linearity results was found. This dependence is statistical only. For measured higher noise spectral density we can expect higher value of nonlinearity. The low frequency noise and non-linearity measurements can be used also for the characterization of contact – resistive layer materials compatibility. The samples with contacts made by different dipping silvers (DiAg) were measured. Contact resistance Rc is created between DiAg contact and resistive layer due to the interaction between the polymer and solvent in both layers. The values of contact resistances were determined from the surface potential distribution measurements. Good correlation between contact resistance and noise and non-linearity results was found.

Noise, Non-linearity, Polymers based TFRs, Charge carrier transport

SEDLÁKOVÁ, V., ŠIKULA, J.

2006

1. 1. 2006

MIDEM

Slovinsko

961-91023-4-7

4th European Microelectronics and Packaging Symposium with Table-Top Exhibition - Proceedings

15

20

6