New experimental results are reported for silicon samples at high fields in different ambients: vacuum, N₂, air, SF₆ and SF₆ + N₂ mixtures, for different experimental conditions. The strong influence of the semiconductor quality and ambient dielectric on the prebreakdown and breakdown response of the system is presented. The high surface flashover sensitivity of semiconductor-vacuum system, as well as the significant interface activity in air and N₂ is explained. Using a new physical model of the breakdown in semiconductor- dielectric systems, a new technique was developed consisting of an in-situ treatment of the semiconductor sample (in vacuum) before performing the high field measurements in SF₆. Dramatic improvement of the voltage hold-off was obtained in one atmosphere (absolute) SF₆. All standard good quality samples, subjected to the vacuum pre-treatment, supported without surface flashover, high fields in the range of 75 - 85 kV/cm, close to the critical breakdown field for SF₆ gas at one atmosphere (approximately 89 kV/cm). The role of different defects in producing premature breakdown by surface flashover in SF₆ is discussed.

Date Published: 9 June 1993
PDF: 12 pages
Proc. SPIE 1873, Optically Activated Switching III, (9 June 1993); doi: 10.1117/12.146565

Published in SPIE Proceedings Vol. 1873:
Optically Activated Switching III
R. Aaron Falk, Editor(s)