Brown dwarf census with the Dark Energy Survey year 3 data and the thin
  disk scale height of early L types
  In this paper we present a catalogue of 11,745 brown dwarfs with spectral
types ranging from L0 to T9, photometrically classified using data from the
Dark Energy Survey (DES) year 3 release matched to the Vista Hemisphere Survey
(VHS) DR3 and Wide-field Infrared Survey Explorer (WISE) data, covering approx
2,400 deg2 up to i_AB=22. The classification method follows the same photo-type
method previously applied to SDSS-UKIDSS-WISE data. The most significant
difference comes from the use of DES data instead of SDSS, which allow us to
classify almost an order of magnitude more brown dwarfs than any previous
search and reaching distances beyond 400 parsecs for the earliest types. Next,
we also present and validate the GalmodBD simulation, which produces brown
dwarf number counts as a function of structural parameters with realistic
photometric properties of a given survey. We use this simulation to estimate
the completeness and purity of our photometric LT catalogue down to i_AB=22, as
well as to compare to the observed number of LT types. We put constraints on
the thin disk scale height for the early L population to be around 450 parsecs,
in agreement with previous findings. For completeness, we also publish in a
separate table a catalogue of 20,863 M dwarfs that passed our colour cut with
spectral types greater than M6. Both the LT and the late M catalogues are found
at https://des.ncsa.illinois.edu/releases/other/y3-mlt
