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.