The single layer MoS2 is attractive for the use in the next-generation low power nanoelectronic devices because of its intrinsic bandgap compared to graphene. In this work, we investigated the transport property of a p-n junction based on two-dimensional MoS2. The n-type and p-type doping are realized through substituting sulfur with chlorine and phosphorus. The device exhibited backward diode-like behavior with large rectifying ratios. We attribute the observed current-voltage characteristics to different heavy doping effect caused by chlorine and phosphorus. Our results may throw light on the electronic modulation of MoS2 and realizations of complemented logics devices based on MoS2.
Two-dimensional material MoS 2 has excellent optical and electrical characteristics and a controllable energy band structure, leading to a high potential value for designing photodetectors. In this work, a kind of van der Waals heterostructure composed of AlN and a MoS 2 photodetector was fabricated. The optical properties of MoS 2 can be improved by the polarization effect of AlN. On this basis, with a 3 nm thick Al 2 O 3 layer deposited on the MoS 2 layer, the strain effects were also investigated to improve the performance of the detector. The result showed that under an illumination of 365 nm wavelength, the stress liner device showed excellent performance relative to the control device and the photocurrent and responsivity were improved by more than five times. Our work provides guidance for developing heterostructure photoelectric devices and also proves the role of strain engineering in improving the performance of photodetectors.
MoS2/GaN van der Waals heterojunction is suitable for the multiband photodetection field due to the nearly lattice match and excellent response capabilities in ultraviolet and visible light regions. In this work, a multilayer MoS2/GaN van der Waals heterojunction was grown by the chemical vapor deposition method and fabricated into an integrated ultraviolet–visible photodetector. Tensile strain was introduced on MoS2/GaN by depositing Al2O3 stress liner using atomic layer deposition. Owing to the tensile strain effect, excellent detection performances were demonstrated, including a responsivity as high as 1.4 × 105 A/W, a noise equivalent power of 5.63 × 10–21 W/Hz1/2, a normalized detectivity of 6.13 × 1021 jones for stress liner GaN photodetector under 280 nm illumination, and 453.3 A/W for stress liner MoS2 photodetector under 460 nm illumination. The shortened response time of the photodetector is attributed to the improved carrier mobility and the separation of MoS2 from air by Al2O3. This work has provided significant guidance for the development of integrated circuits and optical chips.
Strain engineering has been reported to improve the optical and electrical properties of two-dimensional materials, and the adjustable bandgap of MoS2 has great application value in strain engineering. In this work, to explore the influence of the Si3N4 stress liner on the MoS2 photodetector, plasma enhanced chemical vapor deposition was used to deposit a 5 nm Si3N4 film on the surface of the device to introduce strain. The simulation results show that there is tensile strain in the MoS2 area under a Si3N4 layer, which can decrease the bandgap and electron effective mass of MoS2. The measurement results of the device show that the Si3N4 stress liner devices exhibit a higher light response than the Al2O3/MoS2/sapphire photodetector (control devices) under 365 and 460 nm laser illuminations. The maximum photocurrent (Iph) and responsivity (R) of the stress liner device under 365 nm illumination are 4.1 mA and 739.9 A/W, respectively, which are more than 30 times the corresponding value of the control device. Also, the maximum specific detectivity (D*) reached 2.5 × 1011 Jones, and the lowest noise equivalent power is 8.7 × 10−16 W/Hz1/2. Our work proved the feasibility of the Si3N4 stress liner to improve the performance of MoS2 photodetectors.
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