The gas phase ion–molecule reactions in positively and negatively ionized germane/diborane mixtures have been studied by ion trap mass spectrometry. Reaction sequences and rate constants for the most interesting processes have been determined. In positive ionization, formation of Ge-B bonds exclusively occurs through condensation reactions of B_nH_m⁺ ions with germane, followed by H₂ or BH₃ loss. No reactions of ions from germane with B₂H₆ were observed under the experimental conditions used here. In negative ionization, the Ge_nH_m^– (n = 1, 2) ion families react with diborane to yield the Ge_nB_pH_q^– (p = 1, 2) ions, again via dehydrogenation and BH₃ loss, while diborane anions proved to be unreactive. In both positive and negative ionization, Ge-B ions reach appreciable abundances. The present results afford fundamental information about the intrinsic reactivity of gas-phase ions and provide valuable indications about the first nucleation steps ultimately leading to amorphous Ge and B-doped semiconductor ­materials by chemical vapor deposition methods.

Keywords: ion trap mass spectrometry, gas-phase ion chemistry, germane, diborane, semiconductors