Silicon Molecular Beam Epitaxy on Hydrogen-Plasma-Cleaned Substrates

Abstract

A process sequence for low-temperature in situ processing of silicon in an ultra-high vacuum (UHV) multichamber system is presented. For substrate cleaning, a hydrogen/argon discharge plasma was produced with an UHV-compatible plasma source. This low-energy plasma was used to remove, in a single step, native oxide and organic contaminations from the wafer surface at low substrate temperatures (\\lesssim400° C). During the cleaning process the excitation energy of the gas atoms was determined by optical methods. The cleaning process was applied to patterned silicon substrates with micro-shadow masks. Local epitaxial growth by molecular beam epitaxy (MBE) on these substrates was used to fabricate triangular barrier diodes (TBD) to demonstrate the device quality for this cleaning procedure. The crystal quality of the grown layers and the interface was investigated by transmission electron microscopy (TEM). The electrical results for these diodes are in agreement with the grown layer sequence and the chosen dopings.