Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: 2D condensate of electrons and holes in ultrathin MoTe$_2$ photocells   The electron-hole liquid, which features a macroscopic population of
correlated electrons and holes, may offer a path to room temperature
semiconductor devices that harness collective electronic phenomena. We report
on the gas-to-liquid phase transition of electrons and holes in ultrathin
molybdenum ditelluride photocells revealed through multi-parameter dynamic
photoresponse microscopy (MPDPM). By combining rich visualization with
comprehensive analysis of very large data sets acquired through MPDPM, we find
that ultrafast laser excitation at a graphene-MoTe$_2$-graphene interface leads
to the abrupt formation of ring-like spatial patterns in the photocurrent
response as a function of increasing optical power at T = 297 K. These
patterns, together with extreme sublinear power dependence and picosecond-scale
photocurrent dynamics, provide strong evidence for the formation of a
two-dimensional electron-hole condensate.

28
The categories of this paper are: alg-geom
8
The categories of this paper are: hep-ex
18
The categories of this paper are: econ
6
The categories of this paper are: astro-ph
22
The categories of this paper are: chao-dyn
21
The categories of this paper are: adap-org
3
The categories of this paper are: physics
31
The categories of this paper are: ao-sci
34
The categories of this paper are: chem-ph
27
The categories of this paper are: comp-gas
0
The categories of this paper are: hep-ph
30
The categories of this paper are: q-alg
20
The categories of this paper are: acc-phys
13
The categories of this paper are: quant-ph
25
The categories of this paper are: patt-sol
5
The categories of this paper are: gr-qc