Band-Gap Landscape Engineering in Large-Scale 2D Semiconductor van der Waals Heterostructures

Abstract

We present a growth process relying on pulsed laser deposition for the elaboration of complex van der Waals heterostructures on large scales, at a 400 °C CMOS-compatible temperature. Illustratively, we define a multilayer quantum well geometry through successive in situ growths, leading to WSe2 being encapsulated into WS2 layers. The structural constitution of the quantum well geometry is confirmed by Raman spectroscopy combined with transmission electron microscopy. The large-scale high homogeneity of the resulting 2D van der Waals heterostructure is also validated by macro- and microscale Raman mappings. We illustrate the benefit of this integrative in situ approach by showing the structural preservation of even the most fragile 2D layers once encapsulated in a van der Waals heterostructure. Finally, we fabricate a vertical tunneling device based on these large-scale layers and discuss the clear signature of electronic transport controlled by the quantum well configuration with ab initio calculations in support. The flexibility of this direct growth approach, with multilayer stacks being built in a single run, allows for the definition of complex 2D heterostructures barely accessible with usual exfoliation or transfer techniques of 2D materials. Reminiscent of the III–V semiconductors’ successful exploitation, our approach unlocks virtually infinite combinations of large 2D material families in any complex van der Waals heterostructure design.

Almost Perfect Spin Filtering in Graphene-Based Magnetic Tunnel Junctions

“…Furthermore, spin selectivity can be adapted further beyond the Dirac band structure of graphene, for instance using the tailorable band-gaps of TMDC 2D semiconductors family leading to a related K-Q spin filtering effect. 61 The association of 2D materials in heterostructures on top of crystalline spin sources, with 2D stack band structure landscape engineering, 16 could thus provide an efficient solution to propose original spin functions in envisioned complex spin-circuits. 3 , 8 , 10 Overall, this study is an illustration of the opportunities offered by 2D materials-based interfaces with ferromagnets for spintronics post-CMOS visions.…”

“…Spintronics contributed to the birth of the big data era with highly sensitive hard-drive read-heads allowing dramatic data storage scaling . MRAM, the current spintronics flagship application, promises further increases in efficiency and performance of integrated electronic circuits. − Furthermore, a unified spin variable is foreseen as a strong post-CMOS asset to merge in-memory processing with stochastic, neuromorphic, and quantum technologies. − This fuels the quest for further progress in material science toward efficient spin platforms. − Along this direction, 2D materials have appeared particularly exciting in terms of ultimate atomic interface control and multifunctional heterostructure definition. − Graphene represents the archetype of all 2D materials and has been put forward for efficient spin transport . It has indeed been demonstrated to efficiently preserve spin information during transport particularly due to its low spin–orbit coupling associated with high mobilities. , Graphene has furthermore shown promising performances in vertical magnetic tunnel junction (MTJ) spin-valve devices with efficient spin filtering − as well as stark potential for perpendicular magnetic anisotropy (PMA), spin–orbit torques (SOT), and skyrmion topological spin textures. − …”

Pulsed‐Laser‐Deposition Fabricated ZnIn2S4 Photodetectors with Excellent ON/OFF Switching Characteristics toward High‐Temperature‐Resistant Photodetection Applications

“…Therefore, PLD manifests the advantage of accurate replication of stoichiometry from bulk targets to nanofilms, and it is thus particularly appropriate for the growth of 2DLMs with multiple compositions. Most importantly, largearea of 2DLM nanofilms with high uniformity can be readily achieved by PLD, [31][32][33] whereas it is challenging for traditional methods. Therefore, the PLD-grown 2DLM nanofilms are of crucial significance for on-chip device integration.…”

In situ integration of Te/Si 2D/3D heterojunction photodetectors toward UV-vis-IR ultra-broadband photoelectric technologies

“…30 In addition, it is highly scalable, where the deposition area is commonly only limited by the size of substrates. [31][32][33] Therefore, it has many advantages in the preparation of high-performance 2D Te-based device arrays. On the other hand, because the bandgap of Te is relatively small, the dark current of Te based photoconductive detectors is commonly large.…”