Electronic structure and optical responses of chalcopyrite semiconductors ZnSnX_2 (X = P, As, Sb)

Ternary compounds having the chalcopyrite structure are of considerable interest because of their semiconducting, electrical, structural, mechanical and nonlinear optical properties. Chalcopyrite semiconductors ZnSnX_2 (X = P, As, Sb) lack an inversion symmetry. Under strong light irradiation, the noncentrosymmetric material exhibits photocurrents as nonlinear
functions of the electric field of the light. The spontaneous photocurrent is due to the topological
character of the constituting electronic bands; the Berry connection. The photogalvanic effect rectifies light to dc currents and often plays a crucial role in optical devices and solar cells. Under linearly polarized light, the induced photocurrent is usually called shift current originated due to the charge center shift between the valence and conduction bands in the optical excitation. We study the electronic structure, linear and nonlinear optical response, specially the shift current of chalcopyrite
semiconductors ZnSnX_2 (X = P, As, Sb) using Kubo formulism via a multiband approach using first
principles. We analyze the relationship between the response and the matherials properties which
serves as a deep understanding of the shift current effects in noncentrosymmetric materials over
linear response.