Dielectric spectroscopy of Ge2Sb2Te5 and VO2 upon temperature-induced phase transitions

Phase change materials (PCM) forms a platform for multiple applications in modern optics, photonics, microelectronics. In this work, we performed broadband dielectric spectroscopy of Ge
2
Sb
2
Te
5
(GST) and VO
2
phase change materials in a form of thin films on a sapphire substrate. Broadband dielectric response of three different GST phases was retrieved and thoroughly analyzed. Reversible metal-insulator transition (MIT) of VO
2
film was studied over the broad range of temperatures covering typical hysteresis loop of the material. The factor of residual pressure in the sample chamber was considered. Spectroscopy results were supplemented with the electrical conductivity measurements. Reconstructed THz-IR response was analyzed using classical models of complex dielectric permittivity for all the studied phases of PCMs.