Use of Mixed CH₃–/HC(O)CH₂CH₂–Si(111) Functionality to Control Interfacial Chemical and Electronic Properties During the Atomic-Layer Deposition of Ultrathin Oxides on Si(111)

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 atomic-layer deposition (ALD) of Al2O3 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 CH3-/HC(O)CH2CH2-Si(111) surfaces displayed S = 25 ± 7 cm s(-1). During the ALD growth of either Al2O3 or MnO, both the HC(O)CH2CH2-Si(111) and CH3-/HC(O)CH2CH2-Si(111) surfaces produced increased metal oxide deposition at low cycle number, relative to H-Si(111) or CH3-Si(111) surfaces. As detected by X-ray photoelectron spectroscopy after the ALD process, the CH3- and mixed CH3-/HC(O)CH2CH2- functionalized Si(111) surfaces exhibited less interfacial SiOx than was observed for ALD of metal oxides on H-Si(111) substrates.