Comparison of thermal reactions of phosphine on Ge(1 0 0) and Si(1 0 0) by high-resolution core-level photoemission

The thermal decomposition processes of phosphine (PH3) on a Ge(1 0 0)-2×1 surface at temperatures between 325 and 790 K were investigated and compared with those on Si(1 0 0)-2×1. High-resolution synchrotron radiation core-level photoemission spectra indicates that, at room temperature phosphine molecularly adsorbs on the Ge(1 0 0)-2×1 surface, however on the Si(1 0 0)-2×1 it partially dissociates into PH2 and H. Successive annealing of the PH3-saturated Si(1 0 0) and Ge(1 0 0) surfaces at higher temperatures similarly converts PH3 into PH2 and PH2 to P. P atoms form stable P–P and/or P–Si dimers on Si(1 0 0) above 720 K, but exhibit complex bonding configurations on Ge(1 0 0).