  The transition metal dichalcogenide 1T-TaS$_2$ is well known to harbor a rich
variety of charge density wave (CDW) distortions which are correlated with
underlying lattice atom modulations. The long range CDW phases extend
throughout the whole crystal and terminate with charge displacements at the
crystal boundaries. Here we report on the transport properties and capacitance
characteristics of the interface between freshly exfoliated flakes of
1T-TaS$_2$ in intimate van der Waals contact with \textit{n}-type GaAs
substrates. The extracted barrier parameters (ideality, barrier height and
built-in potential) experience pronounced changes across the Mott-CDW
transition in the 1T-TaS$_2$. The CDW-induced changes in barrier properties are
well described by a bond polarization model which upon decreasing temperature
gives rise to an increased potential drop across the interfacial region due to
the localization of carriers and a decreased dielectric constant.
