Modeling the Evolution of Trap States with Thermal Post-deposition
Treatments in Sol-gel Indium Zinc Oxide TFTs
Abstract
Metal oxides have been investigated for use in displays and wearable
electronics, owing to their high mobility in the amorphous state. In
solution-processed oxide thin-film transistors, post-deposition thermal
processing significantly change the film’s transport properties, and is
essential for high-performance devices. The mobility, bias stability and
trapping-detrapping related hysteresis are improved with higher
processing temperatures, which is generally attributed to decreased
localized states which act as electron traps. Here we develop a model to
validate that post-deposition processing indeed changes the density and
properties of the localized states. We obtain good agreement between
this model and the experimental data measured from sol-gel indium zinc
oxide TFTs. When the processing temperature increases from 300 to 500
0C, the model indicates that the trap state density in
the bulk semiconductor and at the interface decrease by a factor of 5
and a factor of 3, respectively. Furthermore, the localized states
become shallower, and the band mobility increases at higher processing
temperatures.