Effect of electrode metals on the depolarisation current characteristics of PVAc thin films. IV

Abstract

Depolarisation current characteristics of PVAc thin films grown from solutions by isothermal immersion technique have been studied as a function of polarising field, temperature and the nature of the vacuum deposited electrode metals-gold, silver, copper and aluminium-by the thermally stimulated depolarisation (TSD) current technique. The TSD current spectrum shows three individual relaxation processes, designated as beta , alpha and alpha ' in the order of their appearance with increasing temperatures. The alpha ' relaxation process is due to the space charge polarisation and is associated with the trapping of the charge carriers injected from the electrodes at the trap level of depth U=1.05 eV. It has been established that this relaxation process is a case of slow retrapping. The nature of the electrodes plays a dominant role in the polarisation mechanism of these films.