Strong second harmonic generation in two-dimensional ferroelectric IV-monochalcogenides

Abstract

The two-dimensional ferroelectrics GeS, GeSe, SnS and SnSe are expected to have large spontaneous in-plane electric polarization and enhanced shift-current response. Using density functional methods, we show that these materials also exhibit the largest effective second harmonic generation reported so far. It can reach magnitudes up to $10$ nm/V which is about an order of magnitude larger than that of prototypical GaAs. To rationalize this result we model the optical response with a simple one-dimensional two-band model along the spontaneous polarization direction. Within this model the second-harmonic generation tensor is proportional to the shift-current response tensor. The large shift current and second harmonic responses of GeS, GeSe, SnS and SnSe make them promising non-linear materials for optoelectronic applications.

4 pages 3 figures, typos fixed, updated references, published version

References in corpus (1)

• High-Pressure Synthesis and Characterization of $\beta$-GeSe - A Semiconductor with Six-Rings in an Uncommon Boat Conformation

Cited by in corpus (5)

• Large Second-Harmonic Generation and Linear Electro-Optic Effect in Trigonal Selenium and Tellurium
• Experimental formation of monolayer group-IV monochalcogenides
• Group-IV monochalcogenide monolayers: two-dimensional ferroelectrics with weak intra-layer bonds and a phosphorene-like monolayer dissociation energy
• Evolution of elastic moduli through a two-dimensional structural transformation
• Significant Second-Harmonic Generation and Bulk Photovoltaic Effect in Trigonal Selenium and Tellurium Chains