Structure of chemically prepared passivation layers on single crystal semiconductor surfaces

Monolayers of S and Cl have useful passivation properties for group IV and III-V semiconductor surfaces. The structures of Ge(111)-Cl; GaAs(111)-Cl; G aAs(111)A-S, GaAs(111)B-S and GaAs(001)-S monolayer-passivated single cryst al semiconductor surfaces have been studied using synchrotron radiation X-r ay absorption fine structure spectroscopy (XAFS). The near edge and extende d fine structure signals are interpreted using comparisons to multiple scat tering XAFS calculations and, in the cases of Ge(111)-Cl and GaAs(111)-Cl, comparison to first-principles calculations. Relationships between the surf ace structure and the development of improved passivated surfaces are discu ssed.