R. M. S. Martins, Forschungszentrum Dresden-Rossendorf, Dresden, Germany; N. Schell, GKSS Research Center Geesthacht, Geesthacht, Germany; R. J. C. Silva, CENIMAT, Monte de Caparica, Portugal; K. K. Mahesh, F. M. Braz Fernandes, CENIMAT - I3N, Monte de Caparica, Portugal; M. Beckers, A. Mücklich, Forschungszentrum Rossendorf, Dresden, Germany
The preferential orientation of NiTi thin films is a crucial factor in determining the shape memory behavior. The texture has a strong influence on the extent of the strain recovery. The relationship between structure and deposition parameters is of extreme importance for future device applications. Our approach is in-situ XRD during deposition carried out in a process chamber installed at a synchrotron radiation beamline. Near-equiatomic films were co-sputtered from Ni-Ti and Ti targets. Substrate type and bias voltage play an important role for the preferred orientation. On naturally oxidized Si(100) substrates the NiTi B2 phase starts by stacking onto (h00) planes and then changes to (110) fiber texture with increasing film thickness. For thermally oxidized Si(100) substrates, this pronounced cross-over is only observed when a bias voltage is applied. The experiments were supplemented by ex-situ TEM and AES allowing an additional deeper insight into the film/substrate interface.
Summary: The preferential orientation of NiTi thin films is a crucial factor in determining the shape memory behavior. The texture has a strong influence on the extent of the strain recovery. The relationship between structure and deposition parameters is of extreme importance for future device applications. Our approach is in-situ XRD during deposition carried out in a process chamber installed at a synchrotron radiation beamline. Near-equiatomic films were co-sputtered from Ni-Ti and Ti targets. Substrate type and bias voltage play an important role for the preferred orientation. On naturally oxidized Si(100) substrates the NiTi B2 phase starts by stacking onto (h00) planes and then changes to (110) fiber texture with increasing film thickness. For thermally oxidized Si(100) substrates, this pronounced cross-over is only observed when a bias voltage is applied. The experiments were supplemented by ex-situ TEM and AES allowing an additional deeper insight into the film/substrate interface.
