Structural Characteristics of Phosphorus-Doped C60 Thin Film Prepared by Radio Frequency-Plasma Assisted Thermal Evaporation Technique

Phosphorus doped C-60 (P:C-60) thin films were prepared by a radio frequency plasma assisted thermal evaporation technique using C-60 powder as a carbon source and a mixture of argon and phosphine (PH3) gas as a dopant precursor. The effects of the plasma power on the structural characteristics of the as-prepared films were then studied using Raman spectroscopy, Auger electron spectroscopy (AES) and X-ray photo-electrons spectroscopy (XPS). XPS and Auger analysis indicated that the films were mainly composed of C and P and that the concentration of P was proportional to the plasma power. The Raman results implied that the doped films contained a more disordered carbon structure than the un-doped samples. The P:C-60 films were then used as a coating layer for the Si anodes of lithium ion secondary batteries. The cyclic voltammetry (CV) analysis of the P:C-60 coated Si electrodes demonstrated that the P:C-60 coating layer might be used to improve the transport of Li-ions at the electrode/electrolyte interface.