CHEMICAL VS PHYSICAL FACTORS IN DRY-ETCHING INDUCED DAMAGE IN THE SI GEXSI1-X SYSTEM/

Dry etching induced damage in n-type strained Si/Si1-xGex heterostruct ures has been studied by conductance and low field magnetoconductance measurements on quantum wires at cryogenic temperatures. Wires were et ched in SF6/O-2 or Cl-2 plasma at different ion energies. The chemical constitution of the sidewalls was measured by XPS, showing Ge enrichm ent after fluorine and Si enrichment after chlorine plasma processing. The overall XPS and electrical data are analysed in terms of dry etch ing induced damage from direct ion impact and a component originating from surface charges and traps due to oxidation of the sidewall reacti on layer.