Controlled Doping Engineering in 2D MoS₂ Crystals toward Performance Augmentation of Optoelectronic Devices

Abstract

Doping engineering of two-dimensional (2D) semiconductors is vital for expanding their device applications, but has been limited by the inhomogeneous distribution of doping atoms in such an ultrathin thickness. Here, we report the controlled doping of Sn heteroatoms into 2D MoS2 crystals through a single-step deposition method to improve the photodetection ability of MoS2 flakes, whereas the host lattice has been well reserved without the random aggregation of the introduced atoms. Atomic-resolution and spectroscopic characterizations provide direct evidence that Sn atoms have been substitutionally doped at Mo sites in the MoS2 lattice and the Sn dopant leads to an additional strain in the host lattice. The detection performance of Sn-doped MoS2 flakes exhibits an order of magnitude improvement (up to R λ ≈ 29 A/W, EQE ≈ 7.8 × 103%, D* ≈ 1011 Jones@470 nm) as compared with that of pure MoS2 flakes, which is associated with electrons released from Sn atoms. Such a substitutional doping process in TMDs provides a potential platform to tune the on-demand properties of these 2D materials.

Enhancing Photodetection Ability of MoS2 Nanoscrolls via Interface Engineering

“…Wavelength-dependent responsivities were synchronously calculated according to the formula R λ = (I light − I dark )/PS, where P is the power intensity of incident light and S is the effective light receiving area of the device (S ≈ 23.5 μm 2 ). 14,64 BaTiO 3 /MoS 2 nanoscrolls (Figure 5b), MoS 2 nanosheets (Figure S3), and MoS 2 nanoscrolls (Figure S4) all exhibit a cutoff value around 680 nm, in line with the PL results. It is worth noting that the BaTiO 3 /MoS 2 nanoscrollbased light sensor reveals a significant enhancement of photoresponsiveness in comparison with its counterparts, promising a leap toward high-performance optoelectronic devices.…”

“…This speed is comparable to that of BaTiO 3 /MoS 2 nanosheets and Sn-doped MoS 2 flakes. 14,32,74 The slower recovery could be attributed to persistent photoconductance (PPC), referring to the fact that a change in the free carrier concentration persists even after removing the excitation; the PPC would thereof affect the operation of the device, for instance, a lower operation temperature is required to suppress PPC effect. 75 It is worth noting that variations in performance from nanoscroll to nanoscroll may be unavoidable.…”

“…The booming research on van der Waals materials brings enormous opportunities for the post-silicon IC technologies because of their unique physical and chemical properties. − Layered materials involving insulators, semiconductors, and metals offer promising candidates to fulfill this goal. , Moreover, their atomic thinness and dangling-free surface facilitate the construction of van der Waals heterostructures in either lateral or vertical fashions. − These new-fashioned heterostructures create a paradigm for interface engineering with designable optoelectronic properties, further broadening their applications in solid-state electronics and optoelectronics. , So far, however, those van der Waals building blocks mostly rely on two-dimensional (2D) components, which are principally assembled through a mechanical exfoliation or direct synthesis process. , Among those, transition-metal dichalcogenides (TMDs), for example, MoS 2 and WS 2 , have emerged as the widely studied 2D van der Waals materials with rich functionalities, including a tunable band structure, good mechanical flexibility, high catalytic activity, anti-magnetism, flame retardance, and so on. − …”

Electret Modulation Strategy to Enhance the Photosensitivity Performance of Two-Dimensional Molybdenum Sulfide

“…Figure a plots current–voltage ( I – V ) characteristics of PTFE/MoS 2 devices exposed to illumination (365–970 nm, approximately 1 mW/cm 2 , the corona charging voltage is −6 kV) and in dark conditions. The responsivity ( R λ ), a key optoelectronic parameter for evaluating the performance of photodetectors, represents the ratio of the generated photocurrent to the laser illumination power; the calculation formula is R λ = I ph P light · S = I light − I dark P light · S where I dark is the dark current, I light is the measured current under incident light, P is the light intensity, and S is the effective area ( S ≈ 109.9 μm 2 ). , The plots of R λ versus wavelengths for PTFE/MoS 2 and MoS 2 photodetectors are given in Figure b, with cutoff values around 680 nm, consistent with those spectral test results. It should be pointed out that the PTFE/MoS 2 light sensors exhibit significantly improved light sensing in comparison with MoS 2 counterparts (Figures c and S4a,b), which is expected to leap toward high-performance optoelectronic devices.…”

Polyaromatic cores for the exfoliation of popular 2D materials

“…10,11 A single layer of MoS 2 has a direct semiconductor band gap of 1.8 eV and a strong photoluminescence. 12 Due to their electronic and optical properties, MoS 2 flakes have been applied in field effect transistors, 13,14 electrocatalysis 15,16 and optoelectronic devices, 17,18 among others. In the case of g-C 3 N 4 , the exfoliated nanosheets also exhibit enhanced properties with respect to the bulk.…”