Ge deposition on Pd(111): adsorption and decomposition of Ge 2H 6

Abstract

The adsorption and decomposition of digermane (Ge 2H 6) on Pd(111) has been studied by Auger electron spectroscopy (AES), temperature-programmed desorption (TPD) and low energy electron diffraction (LEED) methods. Ge 2H 6 adsorbed on Pd(111) at 100 K thermally desorbs during TPD near 118 K from a weakly bound molecular state for Ge 2H 6 exposures near 1.0 × 10 15 cm −2 and higher. Below this exposure, the desorption of Ge 2H 6 is minimal, indicating that thermal dissociation of Ge 2H 6 occurs at the Pd(111) surface. AES results indicate the thermal dissociation of Ge 2H 6 on Pd(111) deposits Ge at the surface. However, no ordering of these Ge overlayers is observed by LEED. Electron bombardment of Ge 2H 6 adsorbed on Pd(111) at 100 K alters the desorption kinetics of Ge-containing species as reflected in TPD spectra. Electron bombardment leads to enhancement of Ge deposition at the surface as measured by AES. Nitric oxide (NO) adsorption has been used as a probe of the surface reactivity of Ge Pd(111) surfaces formed by thermal dissociation of Ge 2H 6 on clean Pd(111). TPD, AES and electron-stimulated desorption ion angular distribution (ESDIAD) measurements indicate that Ge pre-coverage inhibits the adsorption of NO on Pd(111) at 300 K.