Role of incorporated hydrogen on performance and photo-bias instability of indium gallium zinc oxide thin film transistors

Abstract

This study examined the effects of hydrogen incorporation in amorphous indium gallium zinc oxide (IGZO) on the performance and photo-bias stability of the resulting thin-film transistors (TFTs). It was found that the threshold voltage of IGZO TFTs was negatively shifted without significant loss of the field-effect mobility and ION/OFF ratio with increasing hydrogen concentration, suggesting that interstitial hydrogen can act as a shallow donor. The hydrogen-doped device, however, showed more negative bias illumination stress (NBIS) instability than the undoped device, which cannot be explained by the simple shallow donor model. This NBIS-induced degradation might be associated with the increased tailing state distribution, which may stem from a hydrogen-related complex defect or compensation.