Electrodeposition of Germanium from an aqueous solution and conformal deposition of binary and ternary chalcogenide phase change materials
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E-ALD generally refers to an electrochemical deposition where underpotential deposition (UPD) is used as the surface limited reaction to achieve atomic layer control over a deposit. This method can achieve conformal deposition, high uniformity, good crystallinity, excellent trench filling capability and atomic layer level thickness control. In addition, E-ALD normally operates in aqueous solutions under room temperature and ambient pressure. With those merits, E-ALD is considered as a very promising nanofilms deposition methodology for synthesizing GexSbyTez for electronic storage applications. In this dissertation, electrochemical reactions for the deposition of the elements, Ge, Sb and Te, in aqueous solutions were studied first. That data was used to develop initial E-ALD cycle conditions to form the binaries: SbxTey and GexTey. Then approaches for controlling the compositions of the binary materials and the conditions favorable for making films were examined. In the end, GexSbyTez was synthesized by alternating the cycle chemistries for the binaries: SbxTey and GexTey, in various combinations. Conformal nanofilms were formed, exhibiting good crystallinity. The compositions of the GexSbyTez films were found to be readily adjustable. Electrodeposition of Germanium thin films from an aqueous solution has also been achieved for the first time and reported in this dissertation.