Ion beam sputter-deposition of LiCoO_2 films

摘要

LiCoO_2 films, 200 nm in thickness, are produced by ion beam sputter-deposition. The structural, electrical and electrochemical properties of the films are studied by means of X-ray diffraction {XRD), electrical directcurrent-measurements, and electron energy loss spectroscopy (EELS). The influence of preparation parameters like substrate temperature or oxygen partial pressure, are explored. While an oxygen deficiency was observed in films sputtered under pure argon atmosphere, the oxygen content of the thin films increases, significantly, in case of films sputtered under addition of O_2. At substrate temperatures below 300 ℃, XRD measurements reveal a lattice structure similar to the low-temperature-phase, while the formation of the high-temperature-phase is clearly observed at temperatures above 500 ℃ and an Argon/Oxygen ratio of 3/2. Furthermore, the EELS technique is demonstrated to be a sensitive tool to characterize the lithiation state of the sputter-deposited thin films.