SiGe derivatization by spontaneous reduction of aryl diazonium salts

Abstract

International audienceGermanium semiconductors have interesting properties for FET-based biosensor applications since they possess high surface roughness allowing the immobilization of a high amount of receptors on a small surface area. Since SiGe combined low cost of Si and intrinsic properties of Ge with high mobility carriers, we focused the study on this particularly interesting material. The comparison of the efficiency of a functionalization process involving the spontaneous reduction of diazonium salts is studied on Si(1 0 0), SiGe and Ge semiconductors. XPS analysis of the functionalized surfaces reveals the presence of a covalent grafted layer on all the substrates that was confirmed by AFM. Interestingly, the modified Ge derivatives have still higher surface roughness after derivatization. To support the estimated thickness by XPS, a step measurement of the organic layers is done by AFM or by profilometer technique after a O2 plasma etching of the functionalized layer. This original method is well-adapted to measure the thickness of thin organic films on rough substrates such as germanium. The analyses show a higher chemical grafting on SiGe substrates compared with Si and Ge semiconductors

On the chemical grafting of titanium nitride by diazonium chemistry

“…The thickness of the aminophenylene grafted layers could be estimated by the standard overlayer model from the attenuation of the Ti 2p peak intensities before and after modification: 39,40 ‫ܫ/ܫ‬ = exp(− ‫)ߠ݊݅ݏߣ/݀‬ (i) where d is the layer thickness, λ the photoelectron escape depth, θ the takeoff angle, and I/I 0 the ratio of the Ti 2p peak intensities of the bare and grafted surfaces (Figure 4). In our experiment, the takeoff angle was 90°.…”

1-Dodecanethiol based highly stable self-assembled monolayers for germanium passivation

“…1. Since Cullen and co-workers [20] first reported organic functionalization of Ge in 1962 when they demonstrated the attachment of ethyl groups via Grignard reagents to Cl-terminated Ge surface, many other approaches including hydrogermylation [14], alkanethiolates [21] and arenediazonium salts [22,23] were introduced to the Ge functionalization. These passivation schemes commonly rely on an oxide-free and hydrogen-or halogen-terminated surface that can be functionalized via alkyl Grignard reagents [24], photochemical, or thermally activated hydrogermylation reactions [14].…”

Grafting of Oligo(ethylene glycol)-Functionalized Calix[4]arene-Tetradiazonium Salts for Antifouling Germanium and Gold Surfaces

“…In contrast, the reductive grafting of aryldiazonium salts 3,16,17,18 yields stable layers on Ge. 19,20,21 Nevertheless, this technique generates in situ aryl radicals that easily react with the already grafted aryl groups rendering the formation and organization of monolayers difficult to control. 22,23 This document is the Accepted Manuscript version of a Published Work that appeared in final form in Langmuir, copyright © American Chemical Society after peer review and technical editing by the publisher.…”