UV Absorption Spectra of Adlayers of Trimethylgallium and Arsine

The UV absorption spectra of trimethylgallium (TMG) and arsine adsorbed on silica were investigated. The spectrum of the physisorbed layers of TMG and arsine were similar to the corresponding vapor spectra. On the other hand, the spectrum of the chemisorbed TMG layer was quite different. from that of vapor. Arsine can be chemisorbed on the chemisorbed TMG layer, although it cannot be chemisorbed on silica. The spectrum of the co-chemisorbed layer, consisting of TMG and arsine, was found to extend greatly to longer wavelengths.