C. Hamann

Relations between the morphology and conductivity of thin films of tetrathiofulvalinium-tetracyanoquinodimethane

Abstract The techniques of electron and oprical microscopy were used to establish correlations between the morphology and the electrical properties of tetrathiofulvalinium-tetracyanoquinodimethane (TTFTCNQ) thin films. Glass, monocrystalline silicon and the (100) cleavage planes of LiF, KBr and NaCl were used as the substrates. The TTFTCNQ films are polycrystalline but are to some degree oriented depending on the substrate material. Doubly oriented areas diminishing with decreasing substrate temperature during deposition were found on KBr and NaCl. The electrical conductivity depends on the film thickness. Particularly high conductivities are measured at a thickness of about 150 nm. Above 450 nm the disordered growth of a porous film takes place with a corresponding decrease in conductivity. The thin film conductivity was found to be a nearly linear function of the predominant crystallite length.

Growth of monocrystalline silicon islands on insulating substrates

Abstract The growth of device-worthy silicon crystals on insulating substrates would offer a new type of semiconductor technology. Lateral epitaxial growth is demonstrated for several types of structures using island configurations of silicon deposited either onto continuous or onto structure-etched SiO 2 . The crystallization of the deposited silicon islands was performed either by a large-area light pulse or by a zone melting process. With regard to the crystallinity and the flatness the best results were achieved using encapsulated island structures and the zone melting process.