Scanning microwave imaging of optically patterned Ge2Sb2Te5

The measurement of inhomogeneous conductivity in optically crystallized, amorphous Ge2Sb2Te5 (GST) films is demonstrated via scanning microwave impedance microscopy (MIM). Qualitative consistency with expectations is demonstrated in spots crystallized by focused coherent light at various intensities, exposure times, and film thicknesses. The characterization of process imperfections is demonstrated when a mask is used to optically pattern the nanoscale features of crystalline GST in the amorphous film. These measurements show the ability of MIM to resolve partial crystallization, patterning faults, and other details in optically patterned GST.