Articles you may be interested inA thermalization energy analysis of the threshold voltage shift in amorphous indium gallium zinc oxide thin film transistors under simultaneous negative gate bias and illumination Materials in In-Ga-Zn-O system are promising candidates for channel layers of high-performance thin-film transistors ͑TFTs͒. We investigated the atomic arrangements and the electronic structures of crystalline InGaZnO 4 containing point defects such as oxygen vacancy ͑V O ͒, interstitial hydrogen ͑H i ͒, and interstitial oxygen ͑O i ͒ by density functional theory ͑DFT͒ using a plane-wave pseudopotential method. The calculations for the atomic structure relaxation suggest that H i bonds to a lattice oxygen ͑O O ͒, and O i occupies a split interstitial site ͓O i ͑split͔͒ forming a chemical bond with O O which is similar to O 2 molecule, or O i occupies an octahedral interstitial site ͓O i ͑oct͔͒. The electronic structure calculations reveal that V O forms fully occupied states around the middle of the DFT band gap, while H i does not form a defect level in the band gap but raises the Fermi level above the conduction band minimum. O i ͑split͒ forms fully occupied states above the valence band maximum of the defect-free model ͑VBM 0 ͒, while O i ͑oct͒ forms both occupied and unoccupied states above the VBM 0 . It is thus suggested that V O and O i ͑split͒ are electrically inactive for electrons but work as hole traps, H i acts as a donor, and O i ͑oct͒ is electrically active, trapping both electrons and holes. These observations imply that V O and O i ͑split͒ do not but H i and O i ͑oct͒ influence electrical properties of the n-channel TFTs based on the In-Ga-Zn-O semiconductor materials.

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