Defect-induced rigidity enhancement in layered semiconductors

We discuss the mechanism responsible for the observed improvement in the structural properties of In-doped GaSe, a layered material of great current interest. Formation energy calculations show that by tuning the Fermi energy, In can substitute for Ga or can go as an interstitial charged defect ( In i 3+ ) . We find that In i 3+ dramatically increases the shear stiffness of GaSe, explaining the observed enhancement in the rigidity of In-doped p-GaSe. The mechanism responsible for rigidity enhancement discussed here is quite general and applicable to a large class of layered solids with weak interlayer bonding.