SSIMS IDENTIFICATION OF SURFACE INTERMEDIATES IN THE THERMAL-DECOMPOSITION OF TMGA ON SI(100) - COMMENT

Flores, Zhou and White [Surface Science 261 (1992) 99] examined the de composition of trimethylgallium on a 100 K Si(100) sample and reached some unexpected conclusions about the decomposition process. This pape r presents some TPD data which calls into question Flores, Zhou and Wh ite's main conclusions. The new data show that in contrast to the resu lts in Flores, Zhou and White, the trimethylgallium desorbs molecularl y in a series of peaks extending up to 500 K, dimethylgallium desorbs in a series of peaks up to 520 K and monomethylgallium desorbs at 620 K. Desorption of methane, ethylene and methyl radicals is also seen in contrast to Flores, et al. These results show that many of the galliu m-carbon bonds in trimethylgallium stay intact upon adsorption and sub sequent heating in disagreement with the conclusions in Flores, Zhou a nd White. Our conclusion is that at saturation coverages trimethylgall ium decomposes at 100 K via a pathway which is similar to that observe d by Lin and Masel [Surface Science 258 (1991) 225] for a sample dosed at 300 K.