Thermal Desorption Spectroscopy of Sputtered MoSxFilms

Abstract

Thermal desorption spectroscopy (TDS) is introduced as a diagnostic tool for determining the thermal stability of solid lubricant films. In particular, TDS revealed the temperatures at which various decomposition processes occurred as sputtered films were heated in vacuum. The primary film decomposition products detected were SO2 beginning at about 425K, and S2 beginning at about 1150K. A close relationship between water desorption beginning about 400K and SO2 desorption exists in the temperature range 400K-800K. Besides chemical decomposition products, a significant amount of argon trapped in the film during the sputtering process is released at various temperatures. TDS results for sputtered films were compared with results for burnished films and with thermo-gravimetric (TGA) analysis, water adsorption, and other relevant studies of molybdenum disulfide found in the literature. TDS also showed that N+ ion-beam modification of sputtered films resulted in a decrease in desorption of SO2. Along with TDS, X-ray photoelectron spectroscopy (XPS) was used to study the effect of heating on the solid lubricant films. In addition, scanning electron microscopy (SEM), wavelength dispersive spectroscopy (WDS), and Rutherford backscattering spectroscopy (RBS) were used to characterize the samples.