Photodetection Properties of MoS2, WS2 and MoxW1-xS2 Heterostructure: A Comparative Study

Abstract

Layered transition metals dichalcogenides such as MoS2 and WS2 have shown a tunable bandgap, making them highly desirable for optoelectronic applications. Here, we report on one-step chemical vapor deposited MoS2, WS2 and MoxW1-xS2 heterostructures incorporated into photoconductive devices to be examined and compared in view of their use as potential photodetectors. Vertically aligned MoS2 nanosheets and horizontally stacked WS2 layers, and their heterostructure form MoxW1-xS2, exhibit direct and indirect bandgap, respectively. To analyze these structures, various characterization methods were used to elucidate their properties including Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectrometry and high-resolution transmission electron microscopy. While all the investigated samples show a photoresponse in a broad wavelength range between 400 nm and 700 nm, the vertical MoS2 nanosheets sample exhibits the highest performances at a low bias voltage of 5 V. Our findings demonstrate a responsivity and a specific detectivity of 47.4 mA W−1 and 1.4 × 1011 Jones, respectively, achieved by MoxW1-xS2. This study offers insights into the use of a facile elaboration technique for tuning the performance of MoxW1-xS2 heterostructure-based photodetectors.

Broad band modulation of two-dimensional Mo1-x W x S2 by variational compositions

“…38 S2(d)), respectively. The peak at 36.68 eV is ascribed to the W-O bond (figure S2(c)) [43]. The measured atomic ratio between Mo and W is 0.65-0.35, highly consistent to the composition ratio of 0.64-0.36 that measured by EDS on the Mo 0.64 W 0.36 S 2 monolayer, indicating the high credibility of the composition ratios that measured by the EDS measurements.…”

Tailored Synthesis of Heterogenous 2D TMDs and Their Spectroscopic Characterization

“…Transition metal dichalcogenides (TMDs), akin to two-dimensional (2D) layered structures like graphene, have attracted considerable attention and have been widely applied-from insulators and semiconductors to superconductors-owing to their diverse properties [1][2][3]. Recent studies have highlighted the application scope of heterostructures formed by vertically or horizontally stacking different types of single TMD materials, showcasing their potential in the development of optoelectronic systems, solar cells, and nanoelectronic devices [4][5][6][7][8][9][10][11]. Vertical van der Waals heterostructures (vdWHs), e.g., MoS 2 /WS 2 structures, are particularly noteworthy.…”

“…Vertical van der Waals heterostructures (vdWHs), e.g., MoS 2 /WS 2 structures, are particularly noteworthy. Engineered through material selection and junction design, vdWHs operate through phenomena such as light-induced separation or recombination of electron-hole pairs, driving active research in photodetection, photocatalysis, and development of solar cells [5,7,8]. While mechanical exfoliation and transfer processes can be employed for vdWH synthesis and characterization [12,13], films obtained through mechanical exfoliation exhibit low yields and have inconsistent thicknesses and nonuniform size distribution, hindering the use of such methods in large-scale production.…”

Morphological evolution of MoxW1−xS2/MoS2 heterostructures modulated with a growth dynamic process by one-step chemical vapor deposition

“…16 Subsequently, a series of lateral and vertical heterostructures and even superlattice structures have been synthesized by using one-step or two-step CVD growth. [17][18][19][20] For the two-step CVD method, the growth conditions of the TMD materials are controlled independently, which is favorable for obtaining patterned heterostructures, but the 2D TMDs grown on the substrate are exposed to air prior to the second growth step, which introduces defects and contamination in or on the heterostructures. 21 In contrast, the one-step CVD method effectively avoids the complex growth process and is more conducive to producing heterostructures with high crystallinity.…”