Silicon surface preparation for III-V molecular beam epitaxy

• We propose a new Si-substrate surface preparation technique for III-V MBE growth.
• We grow GaSb-based heterostructures on Si-substrates prepared in different ways.
• X-ray characterizations and transmission electron microscopy reveal a better crystalline property with the optimized Si-surface preparation.
• Photoluminescence spectroscopy shows almost two orders of magnitude improvement of the PL efficiency when growth is performed on the Si substrate with an optimized surface preparation.

We report on a silicon substrate preparation for III-V molecular-beam epitaxy (MBE). It combines sequences of ex situ and in situ treatments. The ex situ process is composed of cycles of HF dip and O2 plasma treatments. Ellipsometry and atomic force microscopy performed after each step during the substrate preparation reveal surface cleaning and de-oxidation. The in situ treatment consists in flash annealing the substrate in the MBE chamber prior to epitaxial growth. GaSb-based multiple quantum well heterostructures emitting at 1.55 µm were grown by MBE on Si substrates prepared by different methods. Structural characterizations using XRD and TEM coupled with photoluminescence spectroscopy demonstrates the efficiency of our preparation process. This study thus unravels a simple and reproducible protocol to prepare the Si surface prior to III-V MBE.