Direct simulation Monte Carlo on thermal distribution of rarefied gas under heated atomic force microscope nanoprobe

Heated atomic force microscope (AFM) nanoprobe is an attractive instrument for highly local thermal processing. The gases between the nanoprobe and the sample surface exhibit different behaviors from the macroscopic gases due to the nanoscale probe-sample distance. In this paper, the thermal conduction of rarefied gases heated by an AFM nanoprobe is investigated by means of the direct simulation Monte Carlo method. The heat reservoir of AFM nanoprobe consists of a heater platform and a nanotip. The effects of heater platform and nanotip on the gas heat transfer are analyzed. It is found that both the size of heater platform and the geometry of nanotip have noticeable influence on the heat flux density distribution and the spatial resolution on the sample surface. The results show that a spatial resolution of a few tens of nanometers can be achieved by the hot AFM nanoprobe and the power provided to the spatial scale can be at an order of 10^-8 W. It is also found that a sample surface can be efficiently heated locally without the contact of the nanoprobe and sample, thus alleviating the wear between them and improving the system reliability. The work provides an insight for rational design and optimization of the heated nanoprobe/surface configuration-based systems for topography applications.