Soluble Direct-Band-Gap Semiconductors LiAsS2 and NaAsS2:Large Electronic Structure Effects from Weak As-S Interactions and Strong Nonlinear Optical Response

摘要

Polarity is essential for various technologically important properties,such as nonlinear optics(NLO),piezoelectricity,and ferroelectricity,and a direct gap is important for optoelectronic applications,such as light-emitting diodes(LED),lasers,and solar cells.Chalcopyrite-based materials are polar direct-gap semiconductors that are used both in optoelectronic and NLO applications as second harmonic generators(SHGs)in the IR region,where the use of oxides such as BaBa2O4,LiNbO3,or KTiOPO3 is limited.The non-centrosymmetric packing of asymmetric building units can result in highly polar compounds.