title: Dual passivation of GaAs (110) surfaces using O2/H2O and trimethylaluminum.
abstract: The nucleation and passivation of oxide deposition was studied on defect-free GaAs (110) surfaces to understand passivation of surfaces containing only III-V heterobonds. The passivation process on GaAs (110) was studied at the atomic level using scanning tunneling microscopy while the electronic structure was determined by scanning tunneling spectroscopy (STS). The bonding of the oxidant and reductant were modeled with density functional theory. To avoid Fermi level pinning during gate oxide atomic layer deposition, a dual passivation procedure was required using both a reductant, trimethylaluminum (TMA), and an oxidant, O2 or H2O. Dosing GaAs (110) with TMA resulted in the formation of an ordered complete monolayer of dimethylaluminum which passivates the group V dangling bonds but also forms metal-metal bonds with conduction band edge states. These edge states were suppressed by dosing the surface with oxidants O2 or H2O which selectively react with group III-aluminum bonds. The presence of an ordered Al monolayer with a high nucleation density was indirectly confirmed by XPS and STS.
authors.affiliation: Materials Science and Engineering Program, University of California, San Diego, La Jolla, California 92093, USA.
authors.forename: Tyler J
authors.initials: TJ
authors.lastname: Kent
authors.affiliation: Materials Science and Engineering Program, University of California, San Diego, La Jolla, California 92093, USA.
authors.forename: Mary
authors.initials: M
authors.lastname: Edmonds
authors.affiliation: Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, USA.
authors.forename: Evgueni
authors.initials: E
authors.lastname: Chagarov
authors.affiliation: Department of Physics, Texas State University, San Marcos, Texas 78666, USA.
authors.forename: Ravi
authors.initials: R
authors.lastname: Droopad
authors.affiliation: Materials Science and Engineering Program, University of California, San Diego, La Jolla, California 92093, USA.
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Kummel