Hydrogen Barriers Based on Chemical Trapping Using Chemically Modulated AlO Grown by Atomic Layer Deposition for InGaZnO Thin-Film Transistors.

In this study, the excellent hydrogen barrier properties of the atomic-layer-deposition-grown AlO (ALD AlO) are first reported for improving the stability of amorphous indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs). Chemical species in AlO were artificially modulated during the ALD process using different oxidants, such as HO and O (HO-AlO and O-AlO, respectively). When hydrogen was incorporated into the HO-AlO-passivated TFT, a large negative shift in (ca. -12 V) was observed. In contrast, when hydrogen was incorporated into the O-AlO-passivated TFT, there was a negligible shift in (ca. -0.66 V), which indicates that the O-AlO has a remarkable hydrogen barrier property. We presented a mechanism for trapping hydrogen in a O-AlO via various chemical and electrical analyses and revealed that hydrogen molecules were trapped by C-O bonds in the O-AlO, preventing the inflow of hydrogen to the a-IGZO. Additionally, to minimize the deterioration of the pristine device that occurs after a barrier deposition, a bi-layered hydrogen barrier by stacking HO- and O-AlO is adopted. Such a barrier can provide ultrastable performance without degradation. Therefore, we envisioned that the excellent hydrogen barrier suggested in this paper can provide the possibility of improving the stability of devices in various fields by effectively blocking hydrogen inflows.