MEASUREMENT AND INTERPRETATION OF CARRIER LIFETIME IN SILICON AND GERMANIUM.
Final rept. 1 Dec 66-1 Jan 68,
NATIONAL BUREAU OF STANDARDS WASHINGTON D C
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Minority carrier lifetime is a basic parameter for the specification of semiconductor materials for transistors, diodes, and similar devices. Photoconductive decay measurements are routinely made on many crystals used in the fabrication of these devices. Although this measurement suffers both from lack of precision and from limitations in the range of applicability it is the only method for determination of carrier lifetime which has been accepted as standard. This report describes the results obtained during the first year of a continuing research project which was undertaken in order to determine the fundamental limitations on the precision and applicability of this method and to develop alternate methods which might be more suitable under various conditions. Detailed studies of the photoconductive decay method were accompanied by preliminary studies of the photomagnetoelectric method, the diode recovery time method, and the surface photovoltage method and a critical survey of the various methods which have been reported in the literature. The photoconductive decay method was studied in greatest detail. Different forms of the method were investigated, including the use of both pulsed and chopped light, and employing two methods of measurement, one of which was a null method. The effects of many variables such as light intensity, specimen size and temperature were studied. Author
- Solid State Physics