New Method Of Scanning Tunneling Microscopy Studies And System Development

These years, we have got great achievements in the field of nano-science and technology. SPM(scanning probe microscope) is the basement of the nano-technology development. STM(scanning tunneling microscope) is the first device that gains the real space image of atoms and promote our knowledge of the microcosmic field. Now STM has been widely used in various fields such as physics, chemistry, material science, bioscience, microelectronics and so on. Therefore, the research of STM has significations not only in the theoretics, but in the applications. The main working surroundings of STM are vacuum or atmosphere. These STMs worked in the vacuum are always equipped with advanced components such vacuum chamber and expensive, these conditions limit the popularization and application of STM. The other part of STM worked in the atmosphere has simple structure and cheap comparatively. As the matter of fact, the latter are accepted by more and more people and being widely used in many fields. In this article, we device a novel IDA(impact drive actuator) utilizing friction and inertia to control the approach of the tip and the sample and make progress in the aspect of automation,miniaturization and stability. Using this controlling, the drive has optional moving unit and unlimited distance. This way can also be widely used in many fields.The research content and achievements of this article are as follows:It provided a theoretical discussion of the new drive, using friction and inertia between the drive and sample-holder in order to make the sample-holder get a step. Considering the performance of the china of PZT, we test the state of movement using many driving wave and get two as our controlling wave: one makes the distance of tip-sample nearer, the other makes it farther, and the process of the drive's movement is analyzed in microcosmic. Furthermore, we get a chart by testing this wave by changing the range of the voltage and the periodicity, and the appropriate movement be selected by this chart.We have constructed the experimental setup and many have been improved in this setup. In the aspect of probe system, we use the new drive to realize the position control of the probe-sample in stead of the gear type controller and use a new way for loading and unloading the probe and sample, adopt some measures to improve the anti-interference of thesystem, such as anti-vibration, anti-noise and miniaturization. Furthermore, the preamplifier located nearest possible to the probe system and the four-quadrant scanner adopted make this system upgraded. In the controlling circuit, we make the preamplifier, feedback control and position control circuits optimum designed. In the control software, some parts are added, such as position control, PZT nonlinear adjustment and image optimization. In addition, we adopt the time-sharing multiplex in the way of the drive control to simplify the setup.Using our experimental setup, some experiments have been tested and the structure graphics of the Highly Oriented Pyrolytic Graphite(HOPG) and the gold surface of silicon are gained successfully with different parameters. This new STM system has been improved in miniaturization, automation and application and the result proves our setup is successful and the aim of this project is reached.At the end of this paper, the whole work is summarized and the trend of projection display is discussed briefly.