Mixed silicon–germanium clusters, Si xGe yH z, in the gas phase by flash pyrolysis of silane and germane

Abstract

Bare and partially hydrogenated Si x Ge y H z ( x = 1–3, y = 1–5, z = 0–4) clusters were observed upon flash pyrolysis of a 1:1 mixture of silane (SiH 4) and germane (GeH 4), diluted to 2% each in He at temperatures above ∼1200 K. Thermal decomposition occurred on a short (∼20 μs) time scale after which pyrolysis products were cooled and isolated in a supersonic molecular beam and detected by single photon vacuum ultraviolet (VUV) photoionization time-of-flight mass spectrometry (TOFMS). Cluster formation occurs primarily through insertion of SiH 2 and GeH 2 into silane, germane, polysilanes and polygermanes. Formation of larger Si x Ge y clusters where x + y > 4 may also result from combination of smaller clusters.