Adsorption and decomposition of triethylindium on Si 001/and GaP 001/studied by HREELS and TPD

Adsorption and decomposition of triethylindium TEI.on Si 001.and GaP 001.surfaces have been studied by using temperature-programmed desorption TPD.and high-resolution electron energy loss spectroscopy HREELS.. For TPD spectra of TEI on the Si 001.surface, desorption peaks are found at about 373 and 583 K for ethylene and at about 400 broad., 773, and 923 K for hydrogen. HREELS spectra of the Si 001.surface adsorbed TEI indicate that TEI is adsorbed molecularly at 100 and 290 K and that the orientation of an In–C2H5 bond of TEI is near parallel to the surface above 290 K. Changes in the HREELS spectra at elevated temperatures suggest that the TPD peaks at about 373 and 583 K are due to ethylene produced by cracking TEI molecules in the mass spectrometer and by decomposition of TEI on the surface, respectively. Si–H species are suggested to be formed by decomposition of the ethyl group of TEI through a b-hydride elimination. Two peaks of hydrogen in the TPD spectra at about 773 and 923 K are discussed in terms of adsorption sites. For the GaP 001.surface, adsorbed states of TEI at 100 and 300 K are the same as for the Si 001.surface. Changes in the HREELS spectra at elevated temperatures are consistent with the previous TPD result that ethylene evolved at about 323–473 K and 523–623 K. In contrast to the result for the Si 001., the vibration mode of n Ga–H.is not found, which is discussed in terms of the decomposition mechanisms of TEI and Ga–H species. The ethyl group of TEI is suggested not to be switched off to the Si 001.and GaP 001.surfaces. The difference in the desorption behavior of TEI from the Si 001.and GaP 001.surfaces is discussed. q1998 Elsevier Science B.V. All rights reserved.