The Effect of High-Pressure Hydrogen or Deuterium Annealing on Electrical Performance of Indium Gallium Zinc Oxide Thin-Film Transistors

This study examined the effects of hydrogen (
$\text{H}_{{2}}$
) or deuterium (
$\text{D}_{{2}}$
) annealing on indium gallium zinc oxide (IGZO) channels for the staggered bottom-gate thin-film transistor (TFT). High-pressure annealing (HPA) at 10 bar was used to diffuse and control the amount of
$\text{H}_{{2}}$
and
$\text{D}_{{2}}$
atoms in IGZO thin films.
$\text{H}_{{2}}$
and
$\text{D}_{{2}}$
doping samples were compared with Ar annealed samples to exclude the thermal effects. The performance of both
$\text{H}_{{2}}$
and
$\text{D}_{{2}}$
annealed devices was superior to that of the Ar annealed device. The reliability of
$\text{H}_{{2}}$
and
$\text{D}_{{2}}$
doping devices under positive bias stress was improved due to the defect passivation of
$\text{H}_{{2}}$
and
$\text{D}_{{2}}$
. Larger degradation of the
$\text{H}_{{2}}$
-annealed sample under negative illumination bias stress (NIBS) was observed compared to the Ar-annealed sample, which was explained by the release of positive
$\text{H}_{{2}}$
ions from O–H bonding by the light radiation. With
$\text{D}_{{2}}$
doping, the stability under the NIBS and field-effect mobility was improved significantly compared to the
$\text{H}_{{2}}$
and Ar annealed TFTs (11.2 and 10.6 cm
$^{{2}}\text{V}^{-1}\text{s}^{-1}$
). The large
$\text{D}_{{2}}$
isotope for slow diffusive ability significantly improves the performance and stability of IGZO TFTs.