Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Design of van der Waals Interfaces for Broad-Spectrum Optoelectronics   Van der Waals (vdW) materials offer new ways to assemble artificial
electronic media with properties controlled at the design stage, by combining
atomically defined layers into interfaces and heterostructures. Their potential
for optoelectronics stems from the possibility to tailor the spectral response
over a broad range by exploiting interlayer transitions between different
compounds with an appropriate band-edge alignment. For the interlayer
transitions to be radiative, however, a serious challenge comes from details of
the materials --such as lattice mismatch or even a small misalignment of the
constituent layers-- that can drastically suppress the electron-photon
coupling. The problem was evidenced in recent studies of heterostructures of
monolayer transition metal dichalcogenides, whose band edges are located at the
K-point of reciprocal space. Here we demonstrate experimentally that the
solution to the interlayer coupling problem is to engineer type-II interfaces
by assembling atomically thin crystals that have the bottom of the conduction
band and the top of the valence band at the $\Gamma$-point, thus avoiding any
momentum mismatch. We find that this type of vdW interfaces exhibits radiative
optical transition irrespective of lattice constant, rotational/translational
alignment of the two layers, or whether the constituent materials are direct or
indirect gap semiconductors. The result, which is robust and of general
validity, drastically broadens the scope of future optoelectronics device
applications based on 2D materials.

21
The categories of this paper are: adap-org
1
The categories of this paper are: cs
30
The categories of this paper are: q-alg
5
The categories of this paper are: gr-qc
13
The categories of this paper are: quant-ph
9
The categories of this paper are: nlin
25
The categories of this paper are: patt-sol
26
The categories of this paper are: bayes-an
6
The categories of this paper are: astro-ph
15
The categories of this paper are: nucl-ex
0
The categories of this paper are: hep-ph
35
The categories of this paper are: mtrl-th
36
The categories of this paper are: cmp-lg
3
The categories of this paper are: physics
23
The categories of this paper are: solv-int
31
The categories of this paper are: ao-sci