Hydrogenated IGZO Thin-Film Transistors Using High-Pressure Hydrogen Annealing

Hydrogenation of thin-film indium–gallium–zincoxide (IGZO) is carried out by applying a high-pressure hydrogen annealing (HPHA) process under 5-atm pressure at different temperatures of 260
$^{\circ}{\rm C}$
, 270
$^{\circ}{\rm C}$
, and 280
$^{\circ}{\rm C}$
. The HPHA effectively increases the carrier concentration and the Hall mobility up to
${\sim}{10}^{19}~{\rm cm}^{-3}$
and
${\sim}{6.4}~{\rm cm}^{2}/{\rm Vs}$
, respectively. The HPHA-IGZO films exhibit smoother surfaces as compared with the as-grown films. The HPHA performs at a temperature of 260
$^{\circ}{\rm C}$
that greatly enhances the electrical characteristics of IGZO TFTs, leading to a saturation field effect mobility of 7.4
${\rm cm}^{2}/{\rm Vs}$
, a subthreshold slope of 0.37 V/decade, a threshold voltage of 2.2 V, and an
$I_{{\rm ON}}/I_{{\rm OFF}}$
of
$2.0\times 10^{6}$
.