Light strongly interacts with structures that are of a similar scale to its wavelength, typically nanoscale features for light in the visible spectrum. However, the optical response of these nanostructures is usually fixed during the fabrication. Phase change materials offer a way to tune the properties of these structures in nanoseconds. Until now, phase change active photonics has used materials that strongly absorb visible light, which limits their application in the visible spectrum. In contrast, Sb2S3 is an underexplored phase change material with a bandgap that can be tuned in the visible spectrum from 2.0 to 1.7 eV. This tuneable bandgap is deliberately coupled to an optical resonator such that it responds dramatically in the visible spectrum to Sb2S3 reversible structural phase transitions. It is shown that this optical response can be triggered both optically and electrically. High‐speed reprogrammable Sb2S3 based photonic devices, such as those reported here, are likely to have wide applications in future intelligent photonic systems, holographic displays, and microspectrometers.

Phase-change materials are highly promising for next-generation nonvolatile data storage technology. The pronounced effects of C doping on structural and electrical phase-change behaviors of Ge2Sb2Te5 material are investigated at the atomic level by combining experiments and ab initio molecular dynamics. C dopants are found to fundamentally affect the amorphous structure of Ge2Sb2Te5 by altering the local environments of Ge-Te tetrahedral units with stable C-C chains. The incorporated C increases the amorphous stability due to the enhanced covalent nature of the material with larger tetrahedral Ge sites. The four-membered rings with alternating atoms are reduced greatly with carbon addition, leading to sluggish phase transition and confined crystal grains. The lower RESET power is presented in the PCM cells with carbon-doped material, benefiting from its high resistivity and low thermal conductivity.

Van der Waals heterostructure superlattices of Sb2 Te1 and GeTe are strain-engineered to promote switchable atomic disordering, which is confined to the GeTe layer. Careful control of the strain in the structures presents a new degree of freedom to design the properties of functional superlattice structures for data storage and photonics applications.