A Study of Amorphous Semiconductors for Symmetrical Varistor Applications.
Final rept. 1 Jul 72-31 Dec 74,
JOHNS HOPKINS UNIV LAUREL MD APPLIED PHYSICS LAB
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The purpose of the investigation was to study those switching properties of elemental amorphous semiconducting materials e.g., boron and silicon which are applicable to electromagnetic pulse EMP protection of communications equipment. The major experimental effort during the contract period consisted of measuring switching times and determining their relation to material and electrical parameters. Significant progress was made in 1 understanding of the switching mechanism 2 controlling boron resistivity by the introduction of carbon into the amorphous matrix 3 determining and controlling the switching time parameters, and 4 achieving fast pulse response 10 ns. A model for switching combining thermal and electronic events was formulated. The process depends on voltage, sample geometry and pulsing conditions. A very rapid, high voltage pulse is expected to cause chiefly electronic switching, while a slower rise in voltage signal would lead to mainly thermal switching.
- Electrical and Electronic Equipment
- Solid State Physics