Development Of Scanning Probe Microscopy Based On LabVIEW

With the rapid development of nanotechnology,the applications of many new materials depends on the characterization of the physical properties of materials at the microscale,among which the measurement of thermal properties of nano-scale materials is one of the difficulties.As an important research tool in the development of nanotechnology,scanning probe microscopy has broad application prospects in related fields.In this paper,LabVIEW is used to develop a scanning probe microscopy system,with a home-made probe,which has the ability to measure the surface topography and thermal properties of the sample.Starting from the development history of scanning probe microscopy series,the basic principles of scanning tunneling microscopy,atomic force microscopy,and the scanning thermal microscopy developed therefrom are analyzed.A variety of probes which can be used for thermal measurement,including thermocouple tips and thermoresistive tips,and related applications are explored.In order to further research on the measurement principle and tip–sample heat transfer,the thermoelectric properties of the Pt-Pt and Au-Au nano-contact are measured.The temperature dependence of the electrical contact resistance is used to separate the contributions from the diffusive and ballistic transport.It is found that the thermal contact resistance increases linearly with the increase of the electrical contact resistance,which verified the contact form Wiedemann-Franz law when the electrons transport in the diffusive-ballistic region.Furthermore,an automatic focusing system of optical microscope with multi-field scanning capability is developed,which realize the feedback control of different focusing algorithms.A appropriate scanning algorithm is selected to improve the speed of the system.A Pt-Au T-type wire probe is proposed and made for the first time.The gold wire with a diameter of 30 microns is fused and wrapped with platinum wire by hot-melt welding method to form Ttype wire,then the gold tip is obtained by electrochemical etching.A photoelectric detection system is built to convert the deflection of the probe cantilever into electrical signals corresponding to the position of laser spot.A LabVIEW project is programmed to drive a linear nanopositioning stage to complete the scan progress,use PID feedback to control the Z axis of the stage in order that the laser spot position signal remains unchanged i.e.keep the contact force between the tip and the sample constant,and process the scan data to obtain the surface topography.The error sources and resolution of the scanning probe microscopy are analyzed,and the measurements are compared with those obtained by commercial atomic force microscope.