Single-layer graphene/titanium oxide cubic nanorods array/FTO heterojunction for sensitive ultraviolet light detection

• Published in: Applied surface science Vol. 426; pp. 391 - 398
• Main Authors: Liang, Feng-Xia, Wang, Jiu-Zhen, Wang, Yi, Lin, Yi, Liang, Lin, Gao, Yang, Luo, Lin-Bao
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 31-12-2017
• Subjects: Light trapping effect; MSM junction; Responsivity; UV light photodetector; Wide bandgap semiconductor; MSM junction; Light trapping effect; Responsivity; UV light photodetector; Wide bandgap semiconductor
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2017.07.051

A sensitive ultraviolet photodetector (UVPD) was assembled by coating single-layer graphene on rutile titanium oxide cubic nanorods (TiO2NRs) array that was grown on fluorine-doped tin oxide (FTO) glass through a hydrothermal method. Optoelectronic analysis revealed that the heterojunction device was very sensitive to UV light illumination, with very good responsivity, fast response speed, high specific detectivity, and spectral selectivity.
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•A graphene-TiO2 Schottky junction photodetector was fabricated by simply transferring single layer graphene on rutile titanium oxide cubic nanorods array. Thanks to the excellent light trapping effect, the as-assembled single-layer graphene/cubic TiO2 nanorods array/FTO heterojunction UVPD shows obvious sensitivity to UV light illumination with excellent stability.•The responsivity and specific detectivity were estimated to be 52.1A/W and 4.3×1012 Jones, respectively, which are much high in comparison with other TiO2 nanostructures based devices. What is more, the as-fabricated device exhibited very good spectral selectivity: It is very sensitive to UV light illumination, but virtually blind to illumination in the visible region.•A simple chemical method was developed to reduce the defects concentration in the TiO2NRs array, which is highly beneficial for the optimization of the device performance. It was found that the UVPD after treatment showed obvious decrease in sensitivity, but the response speed (rise time: 80ms, fall time: 160ms) and specific detectivity were substantially increased. It is also found that the speicific detectivity was imporoved by six-fold to 3.2×1013 Jones, which was the best result in comparison with previously reported TiO2 nanostructures or thin film based UVPDs.
In this study, we report on the fabrication of a sensitive ultraviolet photodetector (UVPD) by simply transferring single-layer graphene (SLG) on rutile titanium oxide cubic nanorod (TiO2NRs) array. The cubic TiO2NRs array with strong light trapping effect was grown on fluorine-doped tin oxide (FTO) glass through a hydrothermal approach. The as-assembled UVPD was very sensitive to UV light illumination, but virtually blind to white light illumination. The responsivity and specific detectivity were estimated to be 52.1A/W and 4.3×1012 Jones, respectively. What is more, in order to optimize device performance of UVPD, a wet-chemistry treatment was then employed to reduce the high concentration of defects in TiO2NRs during hydrothermal growth. It was found that the UVPD after treatment showed obvious decrease in sensitivity, but the response speed (rise time: 80ms, fall time: 160ms) and specific detectivity were substantially increased. It is also found that the speicific detectivity was imporoved by six-fold to 3.2×1013 Jones, which was the best result in comparison with previously reported TiO2 nanostructures or thin film based UVPDs. This totality of this study shows that the present SLG/TiO2NR/FTO UVPD may find potential application in future optoelectronic devices and systems.