The Study of Si Surface Structures Essay examples -- Science Experimen

The Study of Si Surface Structures The goal of this study is to determine the ratios of surface type upon the Si sample. Data is collected from the Si samples using SPALEED. By analyzing the data from dates where combined surfaces are present it is possible to determine the amount of certain types of surfaces present on the sample. The ultimate goal is the ability to control the growth of Pb islands upon the Si crystal. Applications of this research include the design of advanced microprocessors and quantum wires. Introduction: The goal of the REU project to which I was assigned is to determine the amounts of certain types of crystalline surface structures present upon the Si crystal that had been used in previous experiments involving the formation of Pb islands at low temperature. This is accomplished by analyzing certain aspects of the data collected by Spot Profile Analysis Low Energy Electron Diffraction (SPALEED). The data sets are taken from different experimental runs involving various surfaces and are compared to one another. These surfaces include combined types of surface structures as well as those with only a single surface structure present. Background and Experimental Procedure: Within ultra-high vacuum and at very low temperature, a Si crystal is placed. This crystal is heated by use of a tungsten filament to high temperatures in order to eliminate impurities. The Si is then heated again at certain temperatures and for specific durations of time in order to create particular crystalline surface structures. Atoms of Pb are then deposited upon the Si crystal by a process of evaporation. The amount of Pb deposited is known and is measured in terms of monolayers, or layers of Pb upon the surface measu... ...is known through previous experiments that the surface of the Si upon which the Pb is deposited can change the height of the Pb islands formed. By altering the silicon surface upon which the Pb is deposited it is hoped that the Pb islands can be controlled. The hope is that the work here can help pave the way for computer chip architecture in the next fifty years. If the Pb islands can be deposited evenly and placed in specific locations it is believed that they can be use as quantum wires, dramatically increasing the speed of the silicon chip computer. At this time the data is promising. With more data and further analysis the problems of controllable Pb island formation are sure to be solved. The use of Scanning Tunneling Microscopy and SPA-LEED are the keys to unlocking the mysteries of the Si surface and it’s connection to the formation of the Pb islands.