| Summary: | 碩士 === 國立高雄大學 === 化學工程及材料工程學系碩士班 === 105 === In this work, LiPON thin films were deposited on Cu foil by rf magnetron sputtering from an Li3PO4 target in a pure N2 atmosphere. We fixed all parameters except N2 flow rate from 15sccm~40sccm. We modified the thin films by H2, Ar mix H2 plasma. X-ray photoelectron spectroscopy (XPS) was used to investigate the chemical bonding of thin films. We analyzed element distribution via secondary ion mass spectrometer(SIMS). The ionic conductivity of LiPON thin films was measured by impedance spectroscopy. To confirm electron contribution, we measured the I-t curve of LiPON thin film then calculated the electron conductivity. At last, we used cyclic voltammetry (CV) to analyze chemical stability of LiPON thin films.
Scanning electron microscopy (SEM) shows the deposited LiPON films are smooth and the interface between LiPON and Cu foil are rugged. The thickness is about 6~8μm. After plasma treatment, the thickness does not change. From XPS spectrum, the ratio of Nt/Nd and the amount of O2 (-O-) bonding increase obviously after plasma treatment. Depth analysis of SIMS spectrum shows that the thin film which was modified by H2 plasma has more H signal on surface. However, there is strong H signal at a depth of 500nm of thin film modified by H2 -Ar mixd plasma. This means that hydrogen is effectively doped into the material.
We can find the ion conductivity increase after plasma treatment. Especially, the thin film modified by mixed plasma its ion conductivity rise nearly ten times than origin. Mover, the electron conductivity of thin film before and after plasma treatment are very small, we can ignore the electron contribution to impedance of material. CV spectrum of LiPON thin film and modified thin film shows that there are no redox peak. This means that the material is very stable at this bias range.
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