Microscale Spatially Resolved Thermal Response of Si Nanotip to Laser Irradiation

Under laser irradiation, the atomic force microscope (AFM) tip can give rise to strong near-field scattering and focusing, leading to strong heating of the tip itself. We report a systematic study of laser heating of an ordinary AFM silicon tip under lateral laser irradiation with micrometer spatial resolution. The temperature rise of the tip can be determined from the relationship between Raman shift versus temperature. The influences of focal situation and energy density of the incident laser on the Raman shift/temperature are studied extensively. The microscale spatially resolved temperature response is also investigated when the laser spot moves along the tip axis until to the cantilever. When the laser irradiates the tip apex, the middle of the tip, and the cantilever, the corresponding temperatures are 603, 754, and 626 K under laser density of 5.6 x 10(8) W/m(2). We substantiate our Raman measurement by theoretically modeling the electric field distribution using the finite element method as well as the heating processing by a one-dimensional heat transport model. Sound agreement between the modeling and experimental result is observed, and discussions are provided about the reasons for their discrepancy.