Gas-phase ion chemistry in the ternary SiH4-C3H6-PH3 system

Propene–phosphine and the silane–propene–phosphine gaseous mixtures were studied by ion trap mass spectrometry. For the binary mixture the variation of ion abundances under different partial pressures and themechanisms of ion–molecule reactions are reported. Moreover, the rate constants of themain processes were measured and compared with the collisional rate constants to determine the reaction efficiencies. In the ternary silane–propene–phosphine mixture the mechanisms of formation of SimCnPpH+s ion clusters were elucidated, but the complexity of the system and the low abundances of the ions usually isolated by successive steps prevented the determination of rate constants. The hydrogenated ternary ions are mainly formed by reactions of SirPsH+t ions with propene, whereas a minor contribution comes from reactions of SimCnH+p ions with phosphine. The CvPwH+z ions show very low reactivity with silane. The formation processes of these species are discussed in relation to their possible role as precursors of amorphous silicon carbides doped with phosphorus obtained by deposition from properly activated silane–propene–phosphine mixtures.