SiGe derivatization by spontaneous reduction of aryl diazonium salts

Aurélie Girard (1) , Florence Geneste (2) , Nathalie . Coulon (1) , Christophe Cardinaud (3) , Tayeb Mohammed-Brahim (1)

1 IETR - Institut d'Électronique et des Technologies du numéRique
2 ISCR - Institut des Sciences Chimiques de Rennes
3 Plasmas et Couches Minces

Germanium 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.

Keywords: Germanium; Diazonium salts; Derivatization; Film thickness; Plasma etching; Semiconductors

Domains: Chemical Sciences; Other

Aurélie Girard, Florence Geneste, Nathalie . Coulon, Christophe Cardinaud, Tayeb Mohammed-Brahim. SiGe derivatization by spontaneous reduction of aryl diazonium salts. Applied Surface Science, 2013, 282, pp.146-155. ⟨10.1016/j.apsusc.2013.05.091⟩. ⟨hal-00860238⟩