posted on 2020-09-04, 18:06authored byEli Sutter, Jia Wang, Peter Sutter
Engineered
heterostructures derive distinct properties from materials
integration and interface formation. Two-dimensional crystals have
been combined to form vertical stacks and lateral heterostuctures
with covalent line interfaces. While thicker vertical stacks have
been realized, lateral heterostructures from multilayer van der Waals
crystals, which could bring the benefits of high-quality interfaces
to bulk-like layered materials, have remained much less explored.
Here, we demonstrate the integration of anisotropic layered Sn and
Ge monosulfides into complex heterostructures with seamless lateral
interfaces and tunable vertical design using a two-step growth process.
The anisotropic lattice mismatch at the lateral interfaces between
GeS and SnS is relaxed via dislocations and interfacial
alloying. Nanoscale optoelectronic measurements by cathodoluminescence
spectroscopy show the characteristic light emission of joined high-quality
van der Waals crystals. Spectroscopy across the lateral interface
indicates valley-selective luminescence in the bulk SnS component
that arises due to anisotropic electron transfer across the interface.
The results demonstrate the ability to realize high-quality lateral
heterostructures of multilayer van der Waals crystals for diverse
applications, e.g., in optoelectronics or valleytronics.