  The room temperature carrier mobility in atomically thin 2D materials is
usually far below the intrinsic limit imposed by phonon scattering as a result
of scattering by remote charged impurities in its environment. We simulate the
charged impurity-limited carrier mobility $\mu$ in bare and encapsulated
monolayer phosphorene. We find a significant temperature dependence in the
carrier mobilities ($\mu \propto T^{-\gamma}$) that results from the
temperature variability of the charge screening and varies with the crystal
orientation. The anisotropy in the effective mass leads to an anisotropic
carrier mobility, with the mobility in the armchair direction about one order
of magnitude larger than in the zigzag direction. In particular, this mobility
anisotropy is enhanced at low temperatures and high carrier densities. Under
encapsulation with a high-$\kappa$ overlayer, the mobility increases by up to
an order of magnitude although its temperature dependence and its anisotropy
are reduced.
