Investigations of the ionizing radiation induced effects in ultra-thin strained-silicon layers on insulator using confocal microscopy measurements

Abstract

This study describes investigations on the ionizing radiation effects induced in ultra-thin Silicon-On-Insulator (SOI) devices. Electrical tests exhibit various behaviors after irradiation which depends on the intrinsic mechanical stress of the thin silicon film. The electrical characteristics of strained Silicon-On-Insulator devices evidence a decrease of the subthreshold slope that may be related to a radiation induced degradation of the carrier mobility. This appears in addition to the deviation of the threshold voltage classically observed on irradiated Silicon-On-Insulator samples. The major issue discussed in this paper is whether a strain relaxation or the buildup of interface states at strained silicon/silica interfaces leads to the observed carrier mobility degradation. Radiation-induced mechanisms are then discussed with electrical measurements and optical spectra obtained by confocal microscopy measurements which have already demonstrated their potential to probe irradiated materials.