Thermal Currents from Corona Charged Mylar

Abstract

Thermal currents have been obtained from corona-charged Mylar. The results are interpreted in terms of electron and/or ion trapping and subsequent release upon reheating. A theory is developed for thermal release of these ``near surface'' charged specimens when no external field is applied. A new method is presented to obtain energies for a series of peaks present in complex thermal current spectra. The trapping parameters are also determined using both the initial rise analysis of Garlick and Gibson, and the curve fitting technique of Cowell and Woods. The results are consistent with four discrete traps in Mylar at depths of 0.55, 0.85, 1.4 and 2.2 (all ±0.1) eV. The 0.55- and 0.85-eV traps are electronic, that at 1.4 eV is either an electronic trap with a Coulomb barrier, or ionic. The 2.2-eV trap is either ionic, interfacial, or involves dissociation of a complex with subsequent release of an electron to the conduction band. Assuming that the traps empty under monomolecular conditions, analysis of the thermal-current peaks yields trap densities of the order of 1016/cm3, an electron mobility—lifetime product of about 10−10 cm2/V, and escape probabilities that agree with those determined from isothermal charge decay.

Silicondioxide electret films prepared by the sol-gel process

“…Activation energies have been estimated by using the initial rise method I181 in combination with peak cleaning techniques [19]. We found an activation energy E; M 1.3 eV corresponding to the peak temperature at -250'C of the TSD current spectrum for the negative corona charged sol-gel sample, E, sz 0.7 eV of the positive corona charged sample.…”

Effect of stretching on space charge behaviour of poly(vinyl chloride) as analysed by the thermal step method and the thermally stimulated depolarization currents technique

“…It is associated with the dipolar orientation of sequences liberated at the glass transition. We have shown in earlier work 2 , by using the peak cleaning technique, 8 that another peak appearing at around 120°C is related to the release of space charge produced by electrode injection. We labelled this a r peak.…”

Electret transducers applied to the telephone

“…For a material such as Teflon@, where the polarization charges are negligible compared to the real charge, there is little to be gained from raising the temperature and a corona discharge is sufficient to produce stable electrets. A very effective method [13] is to draw the film past a knife edge which is connected to a source of high potential. The metallization on one side of the film is connected to the ground.…”