Study On Germanium Telluride Thin Film And Nanowire By Electrodeposition

As one of the most potential new type memory,phase change memory(PCRAM)has attracted more and more people's attention recently.With the development of Moore's law,the storage density of PCRAM is continually increasing,and the the characteristic size of memory devices has already scaling down to below 22 nm.Phase change materials,the functional materials of phase change memory,exhibit distinct characteristics from bulk material when scaling down to nanometer.Study on the size effect of phase change materials is the route one must take to achieve to high-density PCRAM storage.At present,research on this field is limited by the traditional lithography technology,therefore the research of new preparation methods and new material structure becomes very valuable and challenging.Electrochemical deposition is a stable and reliable method for material preparation.We can achieve precise control of material growth and prepare materials with good crystal orientation by adjusting deposition parameters.In this paper,we research the electrochemical preparation method of germanium-containing chalcogenides.Focus on the preparation of Germanium Telluride thin films and nanowires,then characterization and measure them.The main achievements are as follows:(1)Analyzed difficulties in electrochemical deposition of germanium-containing chalcogenides,solutions to reduce the reduction potential difference and restrain the hydrogen evolution reaction were proposed.On the basis of this solution,we deposit germanium telluride thin films on ITO conductive glass.In the experiment,nitrilotriacetic acid was used as complexing agent to reduce the reduction potential difference,adjusting the pH value of the solution in the electrolyte configurationa and controlling the reaction rate by constant current deposition to restrain the hydrogen evolution reaction.Multi group of germanium telluride thin films were deposited with the concentration of complexing agent and current density as variables.By analyzing the morphology,composition and structure of germanium telluride thin films,we found the best deposition conditions was the concentration of complexing agent 0.05mol/L and the current density 2 mA/cm~2.(2)Using Anodic Aluminum Oxide as template,we prepared germanium telluride nanowire by electrochemical deposition.Through the characterization and analysis of germanium telluride nanowires,it was found that the nanowires are face-centered cubic structures with diameters of 50 nanometers,its length ranging from several hundred nanometers to tens of micrometers.By analyzing the result of selected area electron diffraction on Germanium Telluride nanowire,we notice that the crystal interplanar spacing is too large,so the effect of temperature on the structure of germanium telluride was calculated by first principles.The abilty to control structure lay a solid foundation for ultra-low power consumption and non-melting storage in phase-change nanowires.