THE RELATIONS BETWEEN ELECTRICAL NOISE AND DISLOCATIONS IN SILICON.
CARNEGIE INST OF TECH PITTSBURGH PA
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The effect of edge dislocations on electrical noise in n-type silicon was investigated. Parallel arrays of edge dislocations were introduced by plastic deformation in vacuum at near 950C, and the amount of dislocations introduced has been examined by etch pits. Electrical conductivity and noise measurements confirm Shockley-Read model, according to which edge dislocations behave as lines of acceptors in semiconductors with the diamond structure. From the conductivity measurements, values of the fractional disturbed volume, epsilon, of the conductive sample were deduced in accordance with Reads theory. Noise results in dislocated samples show 1f and g-r components differing from those of control samples obtained from the same ingot and also differing from samples subjected to the same heat treatment but without introduced dislocations. The g-r noise can be explained in terns of fluctuations in epsilon, which in turn are caused by fluctuations in the number of captured electrons at the dislocation sites. It was found that, in the temperature range 25C-170C, for 200 ohm-cm samples, the observed time constants and noise amplitudes are consistent with fluctuation phenomena associated with the dislocation sites acting as recombination centers. However, at near and below room temperature trapping at the dislocation sites seems to be the primary cause of the observed noise behavior. Author
- Solid State Physics