Study Of Optical Microscope-monitored Scanning Tunneling Microscope

Nanotechnology is a discipline which is developing rapidly in recent decades, and Scanning Probe Microscope (SPM) is an important basement, which is represented by STM (scanning tunneling microscope and AFM (atomic force microscope), for the development of nanotechnology. Since STM was invented in 1982, it has been an indispensible tool for observation and research in the field of nanotechnology. Therefore, the research about STM system not only has significations, but also has practical value.Currently, imported STM has some advantage of many aspects, while the huge size complex operation, poor shock resistance, without microscopic monitor mostly limit their implement. On the basis of the current STM system technology, in this paper, we have studied about the STM equipped with USB microscopic monitoring, the main research content and achievement are as follows:It proposed and developed a new kind of STM equipped with USB microscopic monitoring system, which combined with the microscopic monitoring unit. We also developed and optimized a scanning and feedback control circuit system, developed a new software system for STM, and built up the whole system, finally, the ideal result of the study were received.The new type of STM probe system composed by the STM probe, XYZ scanning controller, coarse and fine adjustment mechanism portion, USB microscopic monitoring unit and other components are designed. Tripod typed XYZ scanning controller was used in order to increase the scanning driver and the carrying capacity of STM system; The STM probe was combined with USB microscopic monitoring unit to realize the real-time monitoring of the approximation between the probe and the sample; The entire probe was design integrated, greatly improving the capability of shock resistance, stability and practicality.The scanning and feedback control circuit system of STM is made up with a bias circuit, preamplifier, proportional-integral-derivative (PHD) feedback control circuit, XYZ scanning-control circuit, circuit modules of high-voltage amplification part, and the hardware interface. The Bias voltage circuit can achieve a stepless adjustment, while the current preamplifier can converted tunneling current(0.1-10 nA) into a voltage signal, with the using of PID feedback control circuit, the STM can achieve a feedback regulation of the distance between probe and sample in nanometer scale, and the switch of constant height mode and current constant mode.The software system of STM has been developed, which can detect and display the tunneling current for the parameters setting up of bias and reference current; and on the basis of current detecting, scanning samples imaging can be achieved, as well as two-dimensional and three-dimensional image, size calibration and image processing functions.We have established a STM system equipped with USB microscopic monitor, and have carried out sufficiently experimental studies. At first, we have done some analysis and tests on the performance of STM system, the maximum scanning range of STM can reach up to 4000 nmx4000 nm, the total magnification of the microscopic monitoring unit can be adjusted from 10 to 500 times, the resolusion in Z direction is O.Olnm; Then, in different scanning scale and parameters, a variety of sample were taken to be scanned for STM images, it has been concluded that the STM systems equipped with USB microscopic monitoring possess excellent capability, which provide the technical foundation for practical application.