A temperature-programmed desorption/X-ray photoelectron spectroscopy study of ditertiarybutylarsine on GaAs(100)

Abstract

The adsorption of ditertiarybutylarsine [( t-Bu) 2AsH] on GaAs(100) was studied using temperature-programmed desorption (TPD) and X-ray photoelectron spectroscopy (XPS). In TPD, following adsorption at 120 K, three ( t-Bu) 2AsH desorption peaks were observed. They are assigned to physically adsorbed ( t-Bu) 2AsH and two chemically adsorbed states of ( t-Bu) 2AsH. The highest temperature peak was observed to shift from 415 to 375 K with increasing coverage. Following saturation of this peak, a second desorption peak was observed at 230 K. Finally, the TPD peak for a physically adsorbed multilayer was observed at 170 K. No evidence for a β-hydride elimination reaction of t-butyl ligands to isobutene or irreversible decomposition of ( t-Bu) 2AsH was observed. XPS data for both C and As can be deconvoluted to show two separate peaks, one attributed to physisorbed and the other to associatively chemisorbed ( t-Bu) 2AsH.