TEM Moiré Pattern and Scanning Auger Electron Microscope Analysis of Anomalous Si Incorporation into MBE-grown Ge on Si(111)

Abstract

Ge islands are grown by molecular beam epitaxy (MBE) on Si(111) surfaces with an SPE-grown buffer layer, which was expected to prevent intermixing between the epitaxial Ge layer and the Si substrate. The epilayer composition analyzed from the spacing of the Moiré fringe indicates that the Ge islands should be a Si-Ge alloy rather than pure Ge and that the alloying of Ge with Si is greater near the edges of the island. The alloying phenomenon was verified by the compositional depth profile analysis using the scanning Auger electron microscope (SAM) technique. The Si incorporation into the Ge islands observed here cannot be explained by a bulk diffusion mechanism and is a seriously anomalous phenomenon since Si diffusion into Ge would be negligible at the growth temperature and time used ill this experiment.

Transport Modulation in Ge/Si Core/Shell Nanowires through Controlled Synthesis of Doped Si Shells

“…We observed fringe spacings (dark to dark) between 3 and 5 nm from the core of different nanowires, consistent with the spacing of Moir e fringes reported for bulk Si/ Ge. 28,29 Additionally, as shown in the inset of Figure 1d, the fast Fourier transform (FFT) exhibits two nearby, but distinguishable, signals at each reciprocal location: a brighter one at the outer and a lighter one at the inner portion, as indicated by arrows at the [111] position. The measured reciprocal distance difference is 4.0% between these two signals.…”