Interpretation method for mirror experiments based on a Monte Carlo charge implantation model

¹ LPIO (EA 3254), Faculté des Sciences de Nantes, 2 rue de la Houssinière, 44322 Nantes Cedex 03, France
² CEA, Le Ripault, BP 16, 37260 Monts, France

Corresponding author: raphael.renoud@physique.univ-nantes.fr

Received: 3 June 2002
Accepted: 31 July 2002
Published online: 1 October 2002

Abstract

The scanning electron microscope mirror (SEMM) method is considered as a suitable approach for the characterisation of the charge trapping ability of insulators. However, the interpretation of the experimental results is far from being obvious. The aim of this paper is to give some new insights in this problem. Our description of the mirror plots is conventionally based on a multipole analysis of the charge distribution and on the radius of curvature approximation. This approach indicates that the trend of the plots is mainly controlled by the quadrupole contribution. This clearly illustrates the non- uniqueness of the interpretation since different trapped charge distributions, but with nearly equal quadrupole terms, can produce rather similar mirror plots. To make the problem unambiguous, a semi-ellipsoidal shell model is used to account for the implanted space charge. Within this model, we propose a simple method to get the mean density of trapped charge ρ₀. Our Monte Carlo simulations of the charge implantation phase show that ρ₀ can strongly differ from the density of traps N_T. The reasons for these deviations are discussed for a significant set of values of N_T and of the primary energy E_p.