(CaO)(FeSe): A Layered Wide Gap Oxychalcogenide Semiconductor

TL;DR

This paper reports the discovery and structural characterization of a new layered oxychalcogenide semiconductor, (CaO)(FeSe), with a wide band gap and semiconducting properties confirmed by spectroscopy, resistivity, and electronic structure calculations.

Contribution

The study introduces a novel layered oxychalcogenide (CaO)(FeSe) with detailed structural analysis and electronic property characterization, expanding the family of wide-gap semiconductors.

Findings

(CaO)(FeSe) has an orthorhombic structure with layered FeSe2O2 tetrahedra.

It exhibits semiconducting behavior with an indirect band gap of about 1.8 eV.

Electronic calculations suggest a magnetic ground state and confirm the wide band gap.

Abstract

A new iron-oxychalcogenide (CaO)(FeSe) was obtained which crystallizes in the orthorhombic space group Pnma (No. 62) with a = 5.9180(12) {\AA}, b = 3.8802(8) {\AA}, c = 13.193(3) {\AA}. The unique structure of (CaO)(FeSe) is built up of a quasi-two-dimensional network of corrugated infinite layers of corner-shared FeSe2O2 tetrahedra that extend in the ab-plane. The corrugated layers composed of corner-shared FeSe2O2 tetrahedra stack along the c-axis with Ca2+ cations sandwiched between the layers. Optical spectroscopy and resistivity measurements reveal semiconducting behavior with an indirect optical band gap of around 1.8 eV and an activation energy of 0.19(1) eV. Electronic band structure calculations at the density function level predict a magnetic configuration as ground state and confirm the presence of an indirect wide gap in (CaO)(FeSe).