Realization of vertical metal semiconductor heterostructures via solution phase epitaxy

Abstract

The creation of crystal phase heterostructures of transition metal chalcogenides, e.g., the 1T/2H heterostructures, has led to the formation of metal/semiconductor junctions with low potential barriers. Very differently, post-transition metal chalcogenides are semiconductors regardless of their phases. Herein, we report, based on experimental and simulation results, that alloying between 1T-SnS2 and 1T-WS2 induces a charge redistribution in Sn and W to realize metallic Sn0.5W0.5S2 nanosheets. These nanosheets are epitaxially deposited on surfaces of semiconducting SnS2 nanoplates to form vertical heterostructures. The ohmic-like contact formed at the Sn0.5W0.5S2/SnS2 heterointerface affords rapid transport of charge carriers, and allows for the fabrication of fast photodetectors. Such facile charge transfer, combined with a high surface affinity for acetone molecules, further enables their use as highly selective 100 ppb level acetone sensors. Our work suggests that combining compositional and structural control in solution-phase epitaxy holds promises for solution-processible thin-film optoelectronics and sensors.

Template‐Assisted Synthesis of Metallic 1T′‐Sn0.3W0.7S2 Nanosheets for Hydrogen Evolution Reaction

“…The lattice fringe distance measured is ≈0.321 nm, which is consistent with the (100) spacing plane of SnS 2 . Interestingly, the atomically resolved STEM measurement of Sn 0.3 W 0.7 S 2 nanosheets reveals that these flakes are in the 1T′ phase structure, as shown in Figure b, with clear zigzag chains showing the shortest W‐W distance of 2.80 Å, which is in good agreement with previous reports . The Sn ( N = 50, green circle) and W ( N = 74, blue circle) atoms can be distinguished according to the ADF contrast, where heavier atoms appear brighter.…”

“…In addition, the peak intensity at 9.2° becomes much stronger in the case of x = 0.7 due to the more stable structure between W and Sn in the T′ phase. The characteristic peaks at 9.2° and 15.6° are consistent with reported results corresponding to the (002) and (004) planes, respectively . The sharp peak of Sn 0.35 W 0.65 S 2 at ≈15.6° is diminished for Sn 0.3 W 0.7 S 2 , which may be due to the formation of the T′ phase structure and, consequently, the formation of more defects.…”

“…Hence, 1T‐SnS 2 was first prepared by the classical method in the liquid phase . Using the synthesized 1T phase SnS 2 as a template, Sn 1− x W x S 2 alloys with varying W ratios were obtained by adjusting the molar ratios of the precursors SnBr 2 and Na 2 WO 4 .…”

“…Therefore, extensive works have been carried out to study the photoelectric catalytic performance of SnS 2 , for instance, by manipulating visible‐light water splitting . When W is incorporated into 1T‐SnS 2 and reaches 50%, Sn 0.5 W 0.5 S 2 has excellent metallic properties and electrical conductivity . Moreover, the moderate mismatch of atoms may lead to distortion of the octahedron lattice, forming the metastable phase …”

Direct Synthesis of a Self‐Assembled WSe2/MoS2 Heterostructure Array and its Optoelectrical Properties

“…Recently, a novel solution‐based approach has been exploited for synthesizing high‐quality 2D TMD films, which is a simple and inexpensive method to control the number of layers and implement diverse structures . Moreover, it can yield high‐quality heterojunctions, indicating the possibility of fabricating functional devices via a scalable process …”