It was noted that defined placement of biomolecules at Si surfaces was a precondition for a successful combination of Si electronics with biological applications. It was intended to achieve this by Coulomb interaction of biomolecules with dislocations in Si. The dislocations form charged lines and they will be surrounded with a space charge region being connected with an electric field. The electric stray field in a solution of biomolecules, caused by dislocations located close to the Si surface, was estimated to yield values up to few kV/cm. A regular dislocation network could be formed by wafer direct bonding at the interface between the bonded wafers in case of misorientation. The adjustment of misorientation allows the variation of the distance between dislocations in a range from 10nm to a few μm. This was appropriate for nanobiotechnology dealing with protein or DNA molecules with sizes in the nm and lower μm range. A distance, between the dislocations, of 10 to 20nm was achieved. Also the existence of a distinct electric field formed by the dislocation network was demonstrated by the  technique of the electron-beam-induced current. Because of the relatively short range of the field, the dislocations have to be placed close to the surface. The dislocation network was positioned in an interface, 200nm parallel to the Si surface, by layer transfer techniques using H implantation and bonding. Based upon electron beam induced current and luminescence data, the barrier of dislocations at the as-bonded interface was postulated to be <100meV. It was planned to dope the dislocations with metal atoms so as to increase the electric field. It was demonstrated that regular periodic dislocation networks close to the Si surface formed by bonding were realistic candidates for self-organized placing of biomolecules.

Self-Organized Pattern Formation of Biomolecules at Silicon Surfaces - Intended Application of a Dislocation Network. M.Kittler, X.Yu, O.F.Vyvenko, M.Birkholz, W.Seifert, M.Reiche, T.Wilhelm, T.Arguirov, A.Wolff, W.Fritzsche, M.Seibt: Materials Science and Engineering C, 2006, 26[5-7], 902-10