Energy gap of alkaline‐earth‐metal digermanides SrGe2 and BaGe2

Abstract SrGe 2 and BaGe 2 were synthesized by Ar arc‐melting, and their energy gap E g was evaluated using diffuse reflectance measurements. SrGe 2 and BaGe 2 were revealed to be semiconductors with an E g of 0.82 and 0.97 eV, respectively. Since SrGe 2 and BaGe 2 are isostructural with BaSi 2 , the formation of a Ba 1‐ x Sr x Si 2‐ y Ge y solid solution is expected. This result of E g evaluation suggests that the formation of a Ba 1‐ x Sr x Si 2‐ y Ge y solid solution makes it possible to tune E g from 0.82 to 1.20 eV because Ba 0.59 Sr 0.41 Si 2 has been previously reported to have an E g of 1.20 eV. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)