We discuss here the influence of oxide semiconductor thickness on thin-film transistor (TFT) characteristics. We have determined this influence by measuring the transfer characteristics of amorphous InGaZnO (IGZO) TFTs having various IGZO thicknesses and using a simple method to calculate the depletion width in IGZO films. ON current was nearly constant with respect to IGZO thickness because it depended on a high electron density in an accumulation region sufficiently thinner than the IGZO film. The threshold voltage shifted negatively with increasing IGZO thickness, which indicates that a thicker IGZO film requires a higher negative gate voltage for it to be fully depleted. Calculation results suggest that threshold voltage variation due to IGZO thickness variation increases with increasing donor density and IGZO thickness.
ASJC Scopus subject areas
- Physics and Astronomy(all)