Transport Properties of Silica Thermally Grown on Silicon.
Abstract
The total, ionic and electronic conductivity of silica thermally grown on silicon have been determined between 25 - 960 C. Therefrom the ionic transport numbers have been calculated. Utilizing an open circuit emf method, the average ionic transport numbers for silica thermally grown on silicon, for vitreous silica and for single crystalline quartz have been determined between 550 and 950 C. In general, all the silicas studied exhibit mixed conduction, i.e., conduction via ions and electrons. The ionic contribution increases with temperature and attains a maximum at 800 - 900 C. The open circuit emf studies show smaller values of the average ionic transference numbers than those values obtained via conductivity measurements. This apparent discrepancy is attributed to migration of oxygen through pores in the SiO2 grown on Si in the case of the open circuit emf measurement. High resolution transmission electron microscopic studies confirmed the presence of small pores (5 to 8 A in diameter) in the Si02 grown silicon under both wet and dry conditions. A preliminary study of the reaction between molybdenum and SiO2 grown thermally on silicon wafers has been carried out. Mo appears to diffuse into the SiO2 at 1000 and 1100 C as determined by Rutherford Back Scattering techniques. Originator furnished keywords include: Electrical conductivity; Transport/Transference numbers; Silica; Quartz crystals.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 20, 1984
- Accession Number
- ADA150304
Entities
People
- J. B. Wagner Jr.
Organizations
- Arizona State University