title: Electro-optical evidence for the chelate effect at semiconductor surfaces.
abstract: Monoamines and diamines dissolved in cyclohexane solution reversibly enhance the band-edge photoluminescence (PL) intensity of immersed n-type cadmium sulfide (n-CdS) and n-type cadmium selenide (n-CdSe) substrates through adsorption. The magnitude of the PL increase is used to estimate amine-induced contractions in the semiconductor's depletion width, and the dependence of the PL intensity on amine concentration provides an estimate of the adduct formation constant. Two diamines, ethylenediamine and o-phenylenediamine, exhibit unusually low reductions in depletion width and substantially larger adduct equilibrium constants relative to the other amines studied, consistent with chelation to surface Cd(2+) ions. These studies demonstrate that PL can be used as a contactiess, in situ technique for characterizing the steric and electronic landscape of semiconductor surfaces and for correlating molecular and surface chemistry.
authors.forename: G C
authors.initials: GC
authors.lastname: Lisensky
authors.forename: R L
authors.initials: RL
authors.lastname: Penn
authors.forename: C J
authors.initials: CJ
authors.lastname: Murphy
authors.forename: A B
authors.initials: AB
authors.lastname: Ellis