THE USE OF ANTIMONY FOR THE PASSIVATION OF MBE GROWN GAAS-SURFACES

For the preparation of some complex device structures involving molecular beam epitaxy (MBE) it may be necessary to interrupt layer growth, perform an intermediate processing operation and then resume deposition. If the second stage of this sequence is to involve the removal of the substrate from the growth chamber, it is necessary to protect the crystal surface from the effects of contamination or remove the contamination upon reintroduction. This paper describes a method for passivating GaAs surfaces using antimony. The efficiency of the technique was assessed by comparison of pairs of specimens grown to the same specification. Growth of one specimen in each pair was interrupted to allow removal from the UHV environment and subsequent reintroduction to permit resumption of growth on the exposed surface. The same procedure was followed for the second specimen except that antimony was used to passivate the surface upon interruption and the passivating layer was thermally removed upon reintroduction to the growth chamber.