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

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  • Financial support from the NSF (DMR-0801855 and DMR-0306731) and through its MRSEC program (DMR-0076097) at the Materials Research Center of Northwestern University is acknowledged. This work made use of the Analytical Service Laboratory (ASL) and the Electron Probe Instrumentation Center (EPIC), Northwestern University.

Abstract

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Bridging the gap: Li1−xNaxAsS2 (x=0–1) species are found to be a new class of polar direct-gap semiconductors, which display a strong second harmonic generator (SHG) response. The anomalous band-gap trend and their direct-band-gap nature was studied by calculations. The 1.6 eV direct energy gap of LiAsS2 coupled with its high solubility makes it promising as an efficient light harvesting component in solar cells.

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