Determination of the concentration of hot-carrier-induced bulk defects in laser-recrystallized polysilicon thin film transistors

We present a method to investigate hot carrier induced defects in laser recrystallized polysilicon thin film transistors, based on the use of a structure with front and back gate and the analysis of the off current. The maximum process temperature for these devices was 425 °C. We find that both positive and negative VGS produce similar degradation of the characteristics and the main effect is bulk, rather than interface, state creation. The changes in the I–V characteristics are accounted for by an increase of the dangling bond concentration, which is obtained as a fitting parameter, giving a good agreement between experiment and simulation.