Abstract
Abstract MoS2, as a typical representative of two-dimensional semiconductors, has been explored extensively in applications of optoelectronic devices because of its adjustable bandgap. However, to date, the performance of the fabricated photodetectors has been very sensitive to the surrounding environment owing to the large surface-to-volume ratio. In this work, we report on large-scale, high-performance monolayer MoS2 photodetectors covered with a 3-nm Al2O3 layer grown by atomic layer deposition. In comparison with the device without the Al2O3 stress liner, both the photocurrent and responsivity are improved by over 10 times under 460-nm light illumination, which is due to the tensile strain induced by the Al2O3 layer. Further characterization demonstrated state-of-the-art performance of the device with a responsivity of 16.103 A W−1, gain of 191.80, NEP of 7.96 × 10−15 W Hz−1/2, and detectivity of 2.73 × 1010 Jones. Meanwhile, the response rise time of the photodetector also reduced greatly because of the increased electron mobility and reduced surface defects due to the Al2O3 stress liner. Our results demonstrate the potential application of large-scale strained monolayer MoS2 photodetectors in next-generation imaging systems.
Highlights
Ever since the discovery of graphene in 2004, two-dimensional (2D) materials have become a hot topic of research owing to their special properties such as the absence of surface dangling bonds, large surface-to-volume ratio, energy bandgap tunable with the number of layers, as well as adjustable chemical and physical properties [1,2,3,4,5]
We report on large-scale, high-performance monolayer MoS2 photodetectors covered with a 3-nm Al2O3 layer grown by atomic layer deposition
The transmission electron microscopy (TEM) characterization was carried out on the stress liner sample where the monolayer MoS2 was covered by Al2O3
Summary
Ever since the discovery of graphene in 2004, two-dimensional (2D) materials have become a hot topic of research owing to their special properties such as the absence of surface dangling bonds, large surface-to-volume ratio, energy bandgap tunable with the number of layers, as well as adjustable chemical and physical properties [1,2,3,4,5]. Z. Li et al.: High-performance monolayer MoS2 photodetector enabled by oxide stress liner successfully grown large-area monolayer MoS2 films on sapphire substrates and made them into photodetectors with a responsivity of 0.8 mA W−1 [14]. Li et al.: High-performance monolayer MoS2 photodetector enabled by oxide stress liner successfully grown large-area monolayer MoS2 films on sapphire substrates and made them into photodetectors with a responsivity of 0.8 mA W−1 [14] Such low responsivity is unable to meet the requirements for detection capabilities. We have successfully grown high-quality, large area, and continuous monolayer MoS2 on sapphire substrates using CVD, and deposited a 3-nm-thick Al2O3 stress liner grown by ALD to isolate the MoS2 layer from the environment. Al2O3 stress liner, the photocurrent and photoresponsivity of the photodetector increased profoundly, and the response time reduced substantially
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