Use of Mixed CH_3−/HC(O)CH_2CH_2−Si(111) Functionality to Control Interfacial Chemical and Electronic Properties During the Atomic-Layer Deposition of Ultrathin Oxides on Si(111)

Abstract

Silicon surfaces terminated with a mixed monolayer containing both a propyl aldehyde functionality and methyl groups were prepared and used to control the interfacial chemical and electronic properties of Si(111) surfaces during atomiclayer deposition (ALD) of Al_2O_3 or MnO. Si(111) surfaces functionalized only with the aldehyde moiety exhibited surface recombination velocities, S, of 2500 ± 600 cm s^(−1) whereas the mixed CH_3−/HC(O)CH_2CH_2−Si(111) surfaces displayed S = 25 ± 7 cm s^(−1). During the ALD growth of either Al_2O_3 or MnO, both the HC(O)CH_2CH_2−Si(111) and CH_3−/HC(O)CH_2CH_2−Si(111) surfaces produced increased metal oxide deposition at low cycle number, relative to H−Si(111) or CH_3−Si(111) surfaces. As detected by X-ray photoelectron spectroscopy after the ALD process, the CH_3− and mixed CH_3−/HC(O)CH_2CH_2− functionalized Si(111) surfaces exhibited less interfacial SiO_x than was observed for ALD of metal oxides on H−Si(111) substrates.