Polycrystalline In-Ga-O Thin-Film Transistors Coupled with a Nitrogen Doping Technique for High-Performance UV Detectors

Yen Chi Cheng; Sheng Po Chang; Ih Chin Chen; Yen Lin Tsai; Tien Hung Cheng; Shoou Jinn Chang

doi:10.1109/TED.2019.2955758

Polycrystalline In-Ga-O Thin-Film Transistors Coupled with a Nitrogen Doping Technique for High-Performance UV Detectors

Yen Chi Cheng, Sheng Po Chang, Ih Chin Chen, Yen Lin Tsai, Tien Hung Cheng, Shoou Jinn Chang

Research output: Contribution to journal › Article

Abstract

In this article, thin-film transistors (TFTs) with a polycrystalline indium-gallium-oxide (poly IGO) active layer were fabricated for ultraviolet (UV) detection. To achieve better sensing performance, an in situ nitrogen doping (N-doping) technique was employed to passivate the excessive defect states in the bandgap. Under UV illumination, it is evident that the N-doped IGO TFT exhibited superior photoresponsivity and UV-to-visible rejection ratio (17.4 A/W and 1.0 × 10⁶) as compared to the undoped one (13.1 A/W and 1.2 × 10⁵). More importantly, a sharper responsivity cutoff at 340 nm (E_g∼ 3.65 eV) was observed, suggesting that the N-doped phototransistor had better wavelength selectivity. Through X-ray photoelectron spectroscopy analysis, it was shown that N-doping reduced the subgap states and thus suppressed the visible light-induced ionization of oxygen vacancy. Furthermore, the nitrogen incorporation slightly reduced the effective bandgap, which enhanced the band-to-band electron transition and the UV responsivity.

Original language	English
Article number	8933340
Pages (from-to)	140-145
Number of pages	6
Journal	IEEE Transactions on Electron Devices
Volume	67
Issue number	1
DOIs	https://doi.org/10.1109/TED.2019.2955758
Publication status	Published - 2020 Jan

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All Science Journal Classification (ASJC) codes

Electronic, Optical and Magnetic Materials
Electrical and Electronic Engineering

Cite this

Cheng, Y. C., Chang, S. P., Chen, I. C., Tsai, Y. L., Cheng, T. H., & Chang, S. J. (2020). Polycrystalline In-Ga-O Thin-Film Transistors Coupled with a Nitrogen Doping Technique for High-Performance UV Detectors. IEEE Transactions on Electron Devices, 67(1), 140-145. [8933340]. https://doi.org/10.1109/TED.2019.2955758

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abstract = "In this article, thin-film transistors (TFTs) with a polycrystalline indium-gallium-oxide (poly IGO) active layer were fabricated for ultraviolet (UV) detection. To achieve better sensing performance, an in situ nitrogen doping (N-doping) technique was employed to passivate the excessive defect states in the bandgap. Under UV illumination, it is evident that the N-doped IGO TFT exhibited superior photoresponsivity and UV-to-visible rejection ratio (17.4 A/W and 1.0 × 106) as compared to the undoped one (13.1 A/W and 1.2 × 105). More importantly, a sharper responsivity cutoff at 340 nm (Eg∼ 3.65 eV) was observed, suggesting that the N-doped phototransistor had better wavelength selectivity. Through X-ray photoelectron spectroscopy analysis, it was shown that N-doping reduced the subgap states and thus suppressed the visible light-induced ionization of oxygen vacancy. Furthermore, the nitrogen incorporation slightly reduced the effective bandgap, which enhanced the band-to-band electron transition and the UV responsivity.",

author = "Cheng, {Yen Chi} and Chang, {Sheng Po} and Chen, {Ih Chin} and Tsai, {Yen Lin} and Cheng, {Tien Hung} and Chang, {Shoou Jinn}",

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AU - Tsai, Yen Lin

AU - Cheng, Tien Hung

AU - Chang, Shoou Jinn

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N2 - In this article, thin-film transistors (TFTs) with a polycrystalline indium-gallium-oxide (poly IGO) active layer were fabricated for ultraviolet (UV) detection. To achieve better sensing performance, an in situ nitrogen doping (N-doping) technique was employed to passivate the excessive defect states in the bandgap. Under UV illumination, it is evident that the N-doped IGO TFT exhibited superior photoresponsivity and UV-to-visible rejection ratio (17.4 A/W and 1.0 × 106) as compared to the undoped one (13.1 A/W and 1.2 × 105). More importantly, a sharper responsivity cutoff at 340 nm (Eg∼ 3.65 eV) was observed, suggesting that the N-doped phototransistor had better wavelength selectivity. Through X-ray photoelectron spectroscopy analysis, it was shown that N-doping reduced the subgap states and thus suppressed the visible light-induced ionization of oxygen vacancy. Furthermore, the nitrogen incorporation slightly reduced the effective bandgap, which enhanced the band-to-band electron transition and the UV responsivity.

AB - In this article, thin-film transistors (TFTs) with a polycrystalline indium-gallium-oxide (poly IGO) active layer were fabricated for ultraviolet (UV) detection. To achieve better sensing performance, an in situ nitrogen doping (N-doping) technique was employed to passivate the excessive defect states in the bandgap. Under UV illumination, it is evident that the N-doped IGO TFT exhibited superior photoresponsivity and UV-to-visible rejection ratio (17.4 A/W and 1.0 × 106) as compared to the undoped one (13.1 A/W and 1.2 × 105). More importantly, a sharper responsivity cutoff at 340 nm (Eg∼ 3.65 eV) was observed, suggesting that the N-doped phototransistor had better wavelength selectivity. Through X-ray photoelectron spectroscopy analysis, it was shown that N-doping reduced the subgap states and thus suppressed the visible light-induced ionization of oxygen vacancy. Furthermore, the nitrogen incorporation slightly reduced the effective bandgap, which enhanced the band-to-band electron transition and the UV responsivity.

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10.1109/TED.2019.2955758