SILICON MOLECULAR-BEAM EPITAXY ON HYDROGEN-PLASMA-CLEANED SUBSTRATES

A process sequence for low-temperature in situ processing of silicon i n an ultra-high vacuum UHV multichamber system is presented. For subst rate cleaning, a hydrogen/argon discharge plasma was produced with an UHV-compatible plasma source. This low-energy plasma was used to remov e, in a single step, native oxide and organic contaminations from the wafer surface at low substrate temperatures (less than or similar 400- degrees-C). During the cleaning process the excitation energy of the g as atoms was determined by optical methods. The cleaning process was a pplied to patterned silicon substrates with micro-shadow masks. Local epitaxial growth by molecular beam epitaxy (MBE) on these substrates w as used to fabricate triangular barrier diodes (TBD) to demonstrate th e device quality for this cleaning procedure. The crystal quality of t he grown layers and the interface was investigated by transmission ele ctron microscopy (TEM). The electrical results for these diodes are in agreement with the grown layer sequence and the chosen dopings.