Time-temperature dependence of positive gate bias stress and recovery in amorphous indium-gallium-zinc-oxide thin-film-transistors

We have analyzed the time-temperature dependence of positive bias stress (PBS) and recovery in amorphous indium-gallium-zinc-oxide (a-IGZO) Thin-film-transistors (TFTs) incorporating SiO(2) back channel passivation. The data are fitted to stretched exponentials, yielding the time constant tau and stretch parameter beta as fitting parameters. As-fabricated samples and samples annealed in vacuum at 250 degrees C 200 h are compared. The time constant for room temperature stress increases fivefold with the 200 h anneal to the value tau= 1.3 X 10(6) s. The dependence of tau from stress temperature is well described by an Arrhenius plot, with activation E(tau) = 0.95 eV. Stress and recovery show very similar activation energies, supporting the defect formation in the bulk or at the gate insulator/a-IGZO interface as the mechanism responsible for PBS. (C) 2011 American Institute of Physics. [doi:10.1063/1.3580611]