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 Sb₂Se₃ PCMs, 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.