Role of environmental and annealing conditions on the passivation-free in-Ga–Zn–O TFT
Autor: | Po-Tsun Liu, Yi Teh Chou, Simon Min Sze, Chur Shyang Fuh, Li Feng Teng |
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Rok vydání: | 2011 |
Předmět: |
Materials science
Passivation business.industry Scanning electron microscope Annealing (metallurgy) Metals and Alloys Surfaces and Interfaces Surfaces Coatings and Films Electronic Optical and Magnetic Materials Amorphous solid Threshold voltage X-ray photoelectron spectroscopy Thin-film transistor Materials Chemistry Optoelectronics Vacuum chamber business |
Zdroj: | Thin Solid Films. 520:1489-1494 |
ISSN: | 0040-6090 |
DOI: | 10.1016/j.tsf.2011.08.088 |
Popis: | We examined the characteristics of passivation-free amorphous In–Ga–Zn–O thin film transistor (a-IGZO TFT) devices under different thermal annealing atmospheres. With annealing at higher temperature, the device performed better at the above-threshold operation region, which indicated the film quality was improved with the decrease of defects in the a-IGZO active region. The mobility, threshold voltage and subthreshold swing of a-IGZO TFT annealed at 450 °C was 7.53 cm 2 /V s, 0.71 V and 0.18 V/decade, respectively. It was also observed that the a-IGZO was conductive after thermal annealing in the vacuum, due to the ease of oxygen out-diffusion from the a-IGZO back channel. The oxygen deficiency resultantly appeared, and provided leaky paths causing electrical unreliability when TFT was turned off. In contrast, the annealing atmosphere full of O 2 or N 2 would suppress the oxygen diffusion out of the a-IGZO back channel. The worst V th degradation of a-IGZO TFT after positive gate bias stress and negative gate bias stress (NGBS) was about 2 V and − 2 V, respectively. However, the V th shift in the NGBS testing could be suppressed to − 0.5 V in vacuum chamber. Material analysis methods including X-ray photoelectron spectroscopy and scanning electron microscopy were used to investigate the change of a-IGZO film after different thermal annealing treatments. The variation of O 1s spectra with different annealing atmospheres showed the consistence with our proposed models. |
Databáze: | OpenAIRE |
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