Pyrolytic and photolytic dissociation of trimethylgallium on Si and Au substrates

Abstract

Pyrolytic dissociation of trimethylgallium (TMGa) on Si, Au, and Al substrates was studied at various temperatures from 80 to 670 K by x-ray photoelectron spectroscopy of Ga (3d) and C (1s). The intensity and band profile of carbon and gallium signals from TMGa adsorbed on the substrates were measured. The results indicate that TMGa on Si (111) dissociates into Ga and CH3 on the substrate even at 200 K and CH3 further dissociates into C, CH, and CH2 at higher temperatures. Most carbon and gallium species remain on the Si substrate. Carbon species leave the Au and Al substrate but Ga remains on the surface. The pyrolysis of TMGa on GaAs (100), Si (111), and Si (100) substrates is compared and the mechanism of carbon incorporation in photolysis and pyrolysis is discussed. Photodissociation of a monolayer of TMGa on Si and Au is observed with an incident wavelength of 266 nm; direct absorption by the adsorbed molecules occurs at this wavelength. At 355 nm, photodissociation does not occur.