Autodoping of GaAs grown by organometallic vapor phase epitaxy on silicon substrates

We have grown GaAs on silicon substrates by organometallic chemical vapor deposition and we have studied the autodoping of the GaAs layers by silicon during the growth. The epitaxies were performed on GaAs wafers and on GaAs/Si wafers side by side during the same run. By measuring the atomic silicon concentration on the grown layers, we show that a contamination of silicon occurs during the growth process via SiH4 formation and diffusion from the substrate. We propose a model to explain the contamination of the GaAs layers by the silicon substrate.