  Layered indium selenides ($In_{2}Se_{3}$) have recently been discovered to
host robust out-of-plane and in-plane ferroelectricity in the $\alpha$ and
$\beta$' phases, respectively. In this work, we utilise angle-resolved
photoelectron spectroscopy to directly measure the electronic bandstructure of
$\beta '-In_{2}Se_{3}$, and compare to hybrid density functional theory (DFT)
calculations. In agreement with DFT, we find the band structure is highly
two-dimensional, with negligible dispersion along the c-axis. Due to n-type
doping we are able to observe the conduction band minima, and directly measure
the minimum indirect (0.97 eV) and direct (1.46 eV) bandgaps. We find the Fermi
surface in the conduction band is characterized by anisotropic electron pockets
with sharp in-plane dispersion about the $\overline{M}$ points, yielding
effective masses of 0.21 $m_{0}$ along $\overline{KM}$ and 0.33 $m_{0}$ along
$\overline{\Gamma M}$. The measured band structure is well supported by hybrid
density functional theory calculations. The highly two-dimensional (2D)
bandstructure with moderate bandgap and small effective mass suggest that
$\beta'-In_{2}Se_{3}$ is a potentially useful new van der Waals semiconductor.
This together with its ferroelectricity makes it a viable material for
high-mobility ferroelectric-photovoltaic devices, with applications in
non-volatile memory switching and renewable energy technologies.
