Effects of sulfur substitution in amorphous InGaZnO₄: optical properties and first-principles calculations

抄録

Amorphous InGaZnO_4-xS_x thin films were fabricated using a polycrystalline InGaZnO₄ target by pulsed laser deposition in an H₂S gas flow. The optical band gap first decreased from 3.05 to 1.65 eV as x increased from 0 to 1.5, and then increased to 2.6 eV at larger x, showing a bandgap bowing behavior. All the sulfur-containing films have high resistance beyond our measurement limit. Film density of the a-InGaZnS₄ film was decreased by ~40% from that of a-InGaZnO₄. Density functional theory calculations were performed to explain these results.