Nanopatterned Phase-Change Materials for High-Speed, Continuous Phase Modulation

The project explores the vastly different opto-electronic properties of GST in two different phases: amorphous and FCC crystalline. The eventual goal is to design and fabricate photonic devices whose functionality depends on the distinct material properties of the two phases of GST. A prototypical device structure was designed with a lattice of GST nanorods grown on a Silicon substrate. The GST nanorods are surrounded by a thermally conductive material, such as Boron Nitride, that rapidly quenches the nanorods during the phase change. An electrical contract on top of the device is used to initiate the GST phase transition. Simulations for this device design are used to explore the range of values needed for nanorod dimensions and applied voltages to control the phase transitions, as well as determine the effectiveness of the material surrounding the nanorod. Preliminary experiments are conducted to characterize the resistivity and sheet resistance of the GST samples and contact resistance between different GST phases and the contact metals, Tungsten and Molybdenum. The measured contact resistances and calculated sheet resistances for the two metals are comparable