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

In this paper, the impact of high-energy proton irradiation on the low-freq uency 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 beta and on the frequency index gamma is reported. It is shown that for large-square diodes, the irradiations cause a significant increase in t he current noise spectral density S-t in forward operation, for not too hig h forward current I-F. This is accompanied by a reduction of the current in dex from 2 before to 1.5 after irradiation, which indicates a change in the underlying flicker noise mechanism. III order to trace back the origin of the excess 1/f noise, a comparison is made with the microscopic damage coef ficients for the ionisation damage - the linear energy transfer function (L ET)- and the non-ionising energy loss (NIEL) parameter, as a function of th e 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. (C) 2000 Elsevier Science Ltd. All rights reserved.