Application of scanning thermal microscopy for investigation of thermal boundaries in multilayered photonic...

In current work the application of modified Scanning Thermal Microscopy (SThM) technique for thermal imaging of multilayered periodic photonic structures is presented. The measurements were carried out using non-standard operation mode of the SThM. The thermal probe was driven by the sum of DC and small AC currents. The main advantages of presented approach are mechanical stability of the probe during measurements and high sensitivity of AC signal detection by the use of lock-in amplifier. The amplitude and phase components of probe response signal are used for visualization and analysis of the thermal properties of the layer interfaces. Basing on topographic and thermal signals the thermal boundaries between layers were revealed and the periodicity of the structure was analyzed. Presented experiment indicates that the proposed method provides spatial resolution at least about 30% better than 100 nm, which is considered for standard nanofabricated thermal probes. Therefore, proposed technique may be successfully used for the thermal boundaries mapping, as well as for the high-resolution nanoscale imaging of thermal properties distribution. The results prove that thermal imaging provides additional information to that obtained by standard AFM imaging.