Characterization and Investigation of a Hot-Carrier Effect in Via-Contact Type a-InGaZnO Thin-Film Transistors

Electrical characteristics and the effect of hotcarriers are investigated in via-contact-type a-InGaZnO thinfilm transistors. Current-voltage as well as capacitance-voltage measurements are utilized to investigate the impact of top gate bias on device characteristics as well as degradation behaviors caused by a hot-carrier stress. It is found that the redundant source/drain electrodes in via-contact type devices can screen the electric field established by a top gate bias and have significant influence on the device characteristics. Hot-carrier stress brings about electron trapping in the etch stop layer below the redundant electrodes, and this is further verified through modulating the energy band structure by applying a top gate bias during the capacitance-voltage measurement.