Characterization of environment-dependent hysteresis in indium gallium zinc oxide thin film transistors

This study investigates environmentally dependent electrical performance as a function of hysteresis phenomena for amorphous indium–gallium–zinc-oxide (a-IGZO) thin film transistors (TFTs). Because ambient gas has a great influence on the electrical characteristics of zinc oxide-based TFTs during electrical measurements, the hysteresis for current–voltage and capacitance–voltage measurements are employed in different ambient gases (ambient air, vacuum, oxygen ambient and moisture ambient) to study this issue. Although the hysteresis phenomenon has been explained by the charge trapping and de-trapping model, in order to obtain stable electrical characteristics it is necessary to clarify the original principal mechanism leading to threshold voltage instability under gate bias operations in different environments. Also, the relationship between de-trapping rate and electrical hysteresis is investigated by prolonging the integration time of the semiconductor parameter analyzer. This study may be of importance in explaining the dynamic relationship between the TFT electrical characteristics and ambient gas, as well as providing a better understanding of the environment-dependent hysteresis phenomenon of the IGZO TFTs.