Effect of Annealing on Sub-Gap Absorption in Amorphous InGaZnO4 Films
Optical absorption in amorphous InGaZnO4 films was examined by optical transmittance and photothermal spectroscopy using individual cantilever. The amorphous InGaZnO4 films have optical bandgap of ~3.5 eV, and Urbach tail absorption and mid-gap absorption at 2.0-3.0 eV. Mid-gap absorption was reduced by thermal annealing at 300 °C in an atmosphere. This observation indicates that heat-induced structural change causes reduction of gap states in amorphous InGaZnO4 films.
Osamu Hanaizumi and Masafumi Unno
T. Gotoh et al., "Effect of Annealing on Sub-Gap Absorption in Amorphous InGaZnO4 Films", Key Engineering Materials, Vol. 459, pp. 19-22, 2011