Initial stages of Al growth from dimethylaluminum hydride on silicon

We use scanning tunneling microscopy to study the initial stages of ultrahi gh-vacuum chemical vapor deposition of Al on the Si(001)-(2 x 1) surface fr om dimethylaluminum hydride (DMAH). At room tempera ture (300 K), the DMAH molecules adsorb intact in seven distinct configurations, which we identify as the DMAH dimer. After annealing above 525 K the molecules decompose int o H, CH3, and Al. By contrast, the majority of impinging DMAH molecules cra ck when dosed on a surface as cool as 350 K. Dosing at the industrial proce ss temperature of 575 K produces the cleanest aluminum growth. [S0163-1829( 99)07011-3].