Effects of Mg Suppressor Layer on the InZnSnO Thin-Film Transistors

We investigate the effects of magnesium (Mg) suppressor layer on the electrical performances and stabilities of amorphous indium-zinc-tin-oxide (a-ITZO) thin-film transistors (TFTs). Compared to the ITZO TFT without a Mg suppressor layer, the ITZO: Mg TFT exhibits slightly smaller field-effect mobility and much reduced subthreshold slope. The ITZO: Mg TFT shows improved electrical stabilities compared to the ITZO TFT under both positive-bias and negative-bias-illumination stresses. From the Xray photoelectron spectroscopy O1s spectra with fitted curves for ITZO and ITZO: Mg films, we observe that Mg doping contributes to an enhancement of the oxygen bond without oxygen vacancy and a reduction of the oxygen bonds with oxygen vacancies. This result shows that the Mg can be an effective suppressor in a-ITZO TFTs.