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

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 I-ON/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.