Phase change materials for reconfigurable systems

Reconfigurability is a vital feature of future RF, millimeter Wave and terahertz systems for sensing, imaging, wireless, and satellite communications. Indeed significant efforts have been devoted to develop tunable systems in the past among them are RF MEMS switches. But, in practice, these solutions have not been widely implemented due to a need for high voltage actuation, lack of flexibility for integration, reliability issues, and high cost. In contrast to traditional RF MEMS, phase change materials (PCMs) present a major opportunity to address the shortcomings listed above. Among them, vanadium dioxide (VO₂) shows insulator-to-metal transition (IMT) properties with large conductivity change on the order of ~10⁴ at relatively low temperature of T_c ~70 °C. The fundamental mechanism that explains IMT is still unclear. However, unlike other approaches, VO₂ films can be monolithically integrated onto antenna structure or feed networks using microfabrication process.