CONDUCTION PHENOMENA IN RUTILE SINGLE CRYSTALS,
Abstract
The conduction properties of oxidized rutile single crystals have been studied in detail. Application of a constant d-c field results in a rise of conductivity which normally leads to thermal breakdown if the current is not externally limited. The rise starts after a 'delay' period which at room temperature may be hours or days; its length is determined by a critical amount of charge that must pass through the crystal before 'creep' sets in (typical value: 6 coul/sq m). The rate of rise of the conductivity is proportional to the magnitude of the electronic current; it reflects a change in the bulk of the crystal and is not due to changes in the electrode contact. The crystals can be restored to their original state by re-oxidation, e. g., in O2 for twelve hours at 800C. The rise in conductivity seems to be produced by two phenomena: filling of shallow traps with corresponding increase of the effective mobility, and injection of positive space charge as holes from the anode, which allows an increase in electron current by balancing negative space charge. A color cloud also originates at the cathode probably due to trapping of electrons.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1964
- Accession Number
- AD0610101
Entities
People
- John A. Van Raalte
Organizations
- Massachusetts Institute of Technology