Controllable Synthesis of Bandgap-Tunable CuSxSe1-x Nanoplate Alloys

摘要

Composition engineering is an important approach for modulating the physical properties of alloyed semiconductors. In this work, ternary CuSxSe1-x nanoplates over the entire composition range of 0x1 have been controllably synthesized by means of a simple aqueous solution method at low temperature (90 degrees C). Reaction of Cu2+ cations with polysulfide/-selenide ((SnSem)(2-)) anions rather than independent S-n(2-) and Se-m(2-) anions is responsible for the low-temperature and rapid synthesis of CuSxSe1-x alloys, and leads to higher S/Se ratios in the alloys than that in reactants owing to different dissociation energies of the Se-Se and the S-S bonds. The lattice parameters a' and c' of the hexagonal CuSxSe1-x alloys decrease linearly, whereas the direct bandgaps increase quadratically along with the S content. Direct bandgaps of the alloys can be tuned over a wide range from 1.64 to 2.19eV. Raman peaks of the S-Se stretching mode are observed, thus further confirming formation of the alloyed CuSxSe1-x phase.