ECS Journal of Solid State Science and Technology · 2014 · 41 citations · 29 references
EngineeringElectrical EngineeringMaterials ScienceSemiconductor DevicesSemiconductor MaterialsThin FilmsAmorphous Electronic MaterialsAmorphous SemiconductorsSemiconductor Device MaterialsSemiconductor PhysicsSemiconductor Thin FilmsThin-film TransistorsAmorphous Oxide SemiconductorsAmorphous Semiconductor FilmsAmorphous Thin FilmsBias Stress EffectsConduction BandElectronic Density Of StatesOxygen VacanciesThreshold Voltage
Amorphous In-Ga-Zn-O (a-IGZO) thin-film transistors on glass substrates were fabricated, and the density of state (DOS) in TFTs after a negative bias stress (NBS) and negative bias illumination stress (NBIS) was investigated.For a NBIS of -20 V, the threshold voltage (V th ) shifted toward the negative direction but an increase of shallow states expected as positively ionized oxygen vacancies (V o + or V o ++ ) were not observed in the DOS curves.On the other hand, for NBIS of -30 V, changes in the DOS near the conduction band edge before and after applying a bias stress were observed.This suggests that V o + or V o ++ was generated by NBIS but accumulation of holes at the a-IGZO/SiO 2 interface mainly caused the V th shifts.
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