Radiation Effects in Dielectric Materials.
Abstract
A new formulation for the dose rate dependence of irradiaton-induced conductivity in insulators is presented as well as a theory to explain the observed polarization effects in irradiated insulators. Experiments have been performed to test the van Lint-Nichols theory of transient electrical effects in irradiated insulators. The predicated directional dependence of induced conductivity was not shown; however, it was not conclusively ruled out. The specific ionization dependence of the theory appears to have been verified, although not unambiguously. Induced conductivity of several dielectric substrate materials has been measured and the polarization effect in single-crystal sapphire extensively investigated. It appears that the ion-cleaning process preceding electrode evaporation creates surface states that produce a large surface barrier, which is a prime contributor to the polarization effect. Single-crystal sapphire also demonstrated an induced conductivity about two orders of magnitude greater than that of the other dielectric materials tested. Tests on samples of polyethylene, Mylar, and Teflon foils showed linear dependence of the prompt conductivity component on dose rate. Mylar and polyethylene proved to have a linear dependence of total charge transferred (prompt plus delayed) with dose per pulse. A test of two identical monolithic integrated circuits, one with dielectric isolation of components and the other with p-n junction isolation, showed the superior radiation resistance of the dielectric isolation up to 10 to the 9th power rads (Si)/sec. No polarization effects were observed in this test. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1969
- Accession Number
- AD0849945
Entities
People
- J. W. Harrity