title: Electro-optic investigation of the surface trapping efficiency in n-alkanethiol SAM passivated GaAs(001).
abstract: The electro-optic characteristics of the semi-insulating and n(+)-type GaAs(001) surfaces passivated with n-alkanethiol self-assembled monolayers were investigated using Kelvin probe surface photovoltage (SPV) and photoluminescence (PL) techniques. Referencing the equilibrium surface barrier height established in an earlier report, SPV measurements demonstrated a significant (>100 mV) increase in the non-equilibrium band-bending potential observed under low-level photo-injection. Modeling of the SPV accounts for these observations in terms of a large (>10(4)) decrease in the hole/electron ratio of surface carrier capture cross-sections, which is suggested to result from the electrostatic potential of the interfacial dipole layer formed upon thiol chemisorption. The cross-section effects are verified in the high-injection regime based on carrier transport modeling of the PL enhancement manifested as a reduction of the surface recombination velocity.
authors.affiliation: Department of Electrical and Computer Engineering, Université de Sherbrooke, Sherbrooke, QC, Canada.
authors.forename: Gregory M
authors.initials: GM
authors.lastname: Marshall
authors.forename: Gregory P
authors.initials: GP
authors.lastname: Lopinski
authors.forename: Farid
authors.initials: F
authors.lastname: Bensebaa
authors.forename: Jan J
authors.initials: JJ
authors.lastname: Dubowski