Hot-carrier-induced modifications to the noise performance of polycrystalline silicon thin-film transistors

Modifications of noise performances induced by hot-carrier degradation in polycrystalline silicon thin-film transistors, made by excimer laser crystallization, are presented. In particular, the normalized drain current spectral density of these devices shows an evident lif behavior, and as the device characteristics are degraded by prolonged bias stressing, the noise performances worsen. Hot-carrier degradation results in the formation of both interface states, that have been evaluated through the analysis of the sheet conductance, as well as of oxide traps near the insulator/semiconductor interface, as evidenced by the lif noise measurements. A strong correlation between interface state and oxide trap densities has been found, suggesting a common origin for the generation mechanism of the two types of defects. (C) 1997 American Institute of Physics.