Optimizing large optical contrast in Ge-Se-Te films via high-throughput method

Chalcogenide phase-change materials（PCMs） have attracted great attentions due to their potential applications in reconfigurable photonic devices. The Ge2Sb2Te5 and GeTe PCMs exhibit significant difference in refractive index（Δn） between amorphous and crystalline states, but they suffer from high optical loss. The binary Sb2S3 and Sb2Se3PCMs, however, show low optical loss but small Δn. This encourages us to develop the novel materials,which are desired to combine large Δn and low optical loss. Instead of traditional trial-and-error screening method, we here used an efficient high-throughput method to optimize the PCMs' candidates for reconfigurable photonic devices in Ge-Se-Te chalcogenides. The crystallization temperature and difference in optical bandgap were detected, and then the component of Ge25Se7Te68, which also exhibits ultralow optical loss of 1.2 × 10-6（in amorphous state） and large Δn of 1.32 at 1550 nm, was optimized. This Te-rich Ge-Se-Te film can be a candidate for the applications of programmable reconfigurable photonic circuits.