Wurtzite materials in alloys of rock salt compounds

• Published in: Journal of materials research Vol. 35; no. 8; pp. 972 - 980
• Main Authors: Han, Yanbing, Millican, Samantha L., Liu, Jun, Bauers, Sage R., Siol, Sebastian, Lany, Stephan, Al-Jassim, Mowafak, Musgrave, Charles B., Holder, Aaron M., Zakutayev, Andriy
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 28.04.2020; Springer Nature B.V; Materials Research Society
• Subjects: Alloys; Applied and Technical Physics; Biomaterials; Crystal structure; Electrical resistivity; Electronic; energy gap; Enthalpy; Halites; Inorganic Chemistry; inorganic compounds; light absorption; Manganese; manganese compounds; Materials Engineering; Materials research; MATERIALS SCIENCE; Nanotechnology; Optics; Optoelectronics; Photonic and Magnetic Materials; Photonic band gaps; salt deposits; Semiconductors; sputtering zinc sulfide; Surface energy; Temperature; Thin films; Wurtzite
• ISSN: 0884-2914; 2044-5326
• DOI: 10.1557/jmr.2019.402

Materials with crystal structures containing tetrahedral motifs are preferable for optoelectronic applications because they often have direct band gaps and low electron effective masses. However, crystal structures of manganese chalcogenides typically contain octahedral motifs, such as in rock salt (RS) MnS and MnSe materials. Here, we experimentally show that MnS 1− x Se x alloys with tetrahedrally bonded wurtzite (WZ) structure can form between MnSe and MnS parent compounds with octahedral RS structures, at S-rich compositions ( x < 0.4) and low synthesis temperatures ( ∼ 300 °C). The calculated mixing enthalpies of MnS 1− x Se x alloys in RS and WZ structures cannot explain this experimental observation, so we hypothesize that WZ stabilization may be related to smaller structure density and lower surface energy compared with RS. The resulting WZ MnS 1− x Se x alloys have 3.0–3.2 eV optical absorption onset and lower electrical conductivity (<0.0001 S/cm) than the parent RS compounds. These experimental measurement results are consistent with computationally predicted band gaps and effective masses.