  Using first-principles calculations and non-equilibrium Green's function
method, we investigate the ballistic thermal transport in single-layer
phosphorene. A significant crystallographic orientation dependence of thermal
conductance is observed, with room temperature thermal conductance along zigzag
direction being 40 percent higher than that along armchair direction.
Furthermore, we find that the thermal conductance anisotropy with the
orientation can be tuned by applying strain. In particular, the zigzag-oriented
thermal conductance is enhanced when a zigzag-oriented strain is applied but
decreases when an armchair-oriented strain is applied; whereas the
armchair-oriented thermal conductance always decreases when either a zigzag- or
an armchair-oriented strain is applied. The present work suggests that the
remarkable thermal transport anisotropy and its strain-modulated effect in
single-layer phosphorene may be used for thermal management in
phosphorene-based electronics and optoelectronic devices.
