Dislocations structure investigation in neutron irradiated silicon detectors using AFM and microhardness measurements

The structure, microhardness and deformation character for silicon detectors were investigated following a neutron irradiation, using optical and atomic Force (AFM) microscopes. The results of these investigations have given an important contribution to the understanding of silicon damage process by neutron irradiation. It was shown that in the interval of neulron fluences 9.9 x 10^10 <-phi 10^14 n/cm. Different kinds of defects (dislocations and intcrstitials) and their complexes appeared under neutron irradiation. For all fluences the regions ("Whitt;"ʹ "W") with a microhardness smaller than in nonirradiatedsilicon were observed. Microhardness is larger in the regions where the concentration of dislocation loops is high. The "W" regions have a small number of the dislocations loops, and single punctual delects were seen there using atomic Force microscope. The dislocation loops arc placed in specitic ("Black" - "B") regions, which increase in size with the increase of neutron fluence due to a process of vacancies and interstitials accumulation. (C) 1999 Elsevicr Science Ltd. All rights reserved.