NP SThM 01, the ultra-sensitive SThM probe
Through a comprehensive design based on the theory of the quantitative thermal characterization method, null-point scanning thermal microscopy (NP SThM) using NP SThM 01 achieves an ultrahigh sensitivity (~0.5 K/μW) and a nanoscale spatial resolution, even in an atmospheric environment. To maximize the thermal sensitivity, the cantilever and tip of the probe are made of SiO2, and the size of the gold-chrome thermocouple junction integrated at the end of the tip is reduced to ~100 nm. Moreover, to minimize the influence of the absorbed heat flux from the feedback laser on the reflector, the reflector is located far away from the tip, and fins are attached to the reflector so that the absorbed heat flux is dissipated to the surrounding air before the heat flux can reach the tip. Because NP SThM 01 allows a point-heating and point-sensing scheme, it is ideal for the local measurement of temperature and thermal properties.
a. The SEM images of NP SThM 01. b. Schematic diagram of the structure of SThM probe (not to scale).
Tip radius Electrical resistance Seebeck coefficient
50 ± 10nm 600 ± 50 Ω 20.5 μV/K
Cantilever length Tip height Tip half angle
200 μm 10 ± 1 μm 21 o