Temperature dependence of low-frequency excess noise in junction-gate FET´s

The low-frequency noise in silicon JFET´s was measured continuously for temperatures varying from 30 to 300 K. Distinct peaks in the noise were observed for all transistors tested, suggesting the presence of distinct trapping levels in the forbidden gap. An attempt to match theory with experiment indicates that one of the peaks can be explained by the presence of gold in the silicon as expected. However, a discrete trapping level cannot explain the second peak observed in the noise, as unrealistic capture cross sections for the traps would be required. It appears that the mechanism causing this second peak also contributes to the noise level at higher frequencies, and more work must be done to determine the exact nature of the processes involved. A third peak at lower temperatures cannot be explained with present theory. Possible causes of the noise appear to be dislocations in the crystal lattice, gold acceptors, and a splitting of the gold level due to strain.