Inversion phenomenon as a result of junction damages in neutron irradiatedsilicon detectors

This paper concerns with integrated microscopic investigations of bipolar j unction damages in silicon detectors following neutron irradiation. This ph enomenon was studied by means of an advanced contact potential difference m ethod in atomic force microscopy (AFM). The obtained results were confirmed by topographical investigations also done by AFM and electron beam induced current, installed on a conventional scanning electron microscope. The mos t detailed structural investigations were carried out by means of scanning tunnel microscope. It was found that in the interval of neutron fluences, P hi, 9.9 x 10(10) less than or equal to Phi less than or equal to 3.12 x 10( 15) n/cm(2) the damage to the silicon lattice structure is accumulative, fr om small point defects to high defect accumulations. These defects consiste d of large complexes of dislocation loops and vacancies, however, in the p- n junction region, only vacancies remained. This deterioration in the junct ion crystalline structure, resulted in a population inversion of the free c harge carriers, from n- to p-type. The novelty of this research consists of the direct correlation, found between the structural defects and the mecha nical and electrical properties of the diode junction. (C) 2001 Elsevier Sc ience Ltd. All rights reserved.