The impact of high-energy proton irradiation on the low-frequency 1/ f noise in FZ-silicon diodes

Abstract

In this paper, the impact of high-energy proton irradiation on the low-frequency 1/ f noise in p-type float-zone Si diodes is described and analysed in detail. More in particular, the effect on the noise magnitude, the current index β and on the frequency index γ is reported. It is shown that for large-square diodes, the irradiations cause a significant increase in the current noise spectral density S I in forward operation, for not too high forward current I F. This is accompanied by a reduction of the current index from 2 before to 1.5 after irradiation, which indicates a change in the underlying flicker noise mechanism. In order to trace back the origin of the excess 1/ f noise, a comparison is made with the microscopic damage — coefficients for the ionisation damage the linear energy transfer function (LET) — and the non-ionising energy loss (NIEL) parameter, as a function of the proton energy in the range 10–100 MeV. The results strongly suggest that the source of the additional 1/ f noise after proton exposure is located at the diode periphery rather than in the bulk.