3Sr(Ag{sub 1-x}Li{sub x}){sub 2}Se{sub 2} and [Sr{sub 3}Se{sub 2[(Ag{sub 1-x}Li{sub x}){sub 2}Se{sub 2 tunable direct band gap semiconductors.
Authors
Zhou, Xiuquan; Wilfong, Brandon; Chen, Xinglong; Laing, Craig C.; Pandey, Indra; Chen, Ying-Pin; Chen, Yu-Sheng; Chung, Duck-Young; Kanatzidis, Mercouri
Abstract
Synthesizing solids in molten fluxes enables the rapid diffusion of soluble species at temperatures lower than in solid-state reactions, leading to crystal formation of kinetically stable compounds. In this study, we demonstrate the effectiveness of mixed hydroxide and halide fluxes in synthesizing complex Sr/Ag/Se in mixed LiOH/LiCl. We have accessed a series of two-dimensional Sr(Ag1-xLix)(2)Se-2 layered phases. With increased LiOH/LiCl ratio or reaction temperature, Li partially substituted Ag to form solid solutions of Sr(Ag1-xLix)(2)Se-2 with x up to 0.45. In addition, a new type of intergrowth compound [Sr3Se[(Ag1-xLix)(2)Se- was synthesized upon further reaction of Sr(Ag1-xLix)(2)Se-2 with SrSe. Both Sr(Ag1-xLix)(2)Se-2 and [Sr3Se[(Ag1-xLix)(2)Se- exhibit a direct band gap, which increases with increasing Li substitution (x). Therefore, the band gap of Sr(Ag1-xLix)(2)Se-2 can be precisely tuned via fine-tuning x that is controlled by only the flux ratio and temperature.