  We study the electronic structure of WTe$_2$ thin film fakes with different
thickness down to 11 nm. Angle-dependent quantum oscillations reveal a
crossover from a three-dimensional (3D) to a two-dimensional (2D) electronic
system when the sample thickness is reduced below 26 nm. The quantum
oscillations further show that the Fermi pockets get smaller as the samples are
made thinner, indicating that the overlap between conduction and valence bands
is getting smaller and implying the spatial confinement could lift the overlap
in even thinner samples. In addition, the quadratic magnetoresistance (MR) also
shows a crossover from 3D to 2D behavior as the samples are made thinner, while
gating is shown to affect both the quadratic MR and the quantum oscillations of
a thin sample by tuning its carrier density.
