Ion Beam Assisted Deposition

Figure 1: Principle of ion-beam assisted deposition
Figure 2: RHEED pattern of: (a) a 5 nm thin TiN film prepared by IBAD; (b) a 45 nm thick TiN layer grown homoepitaxially on the IBAD layer

Ion beam assisted deposition (IBAD) offers the unique possibility to prepare biaxially textured films on amorphous or arbitrary textured substrates. In this approach, an ion-beam having a defined angle towards the substrate normal is used simultaneously to the deposition process (Fig. 1). The interaction between ions (having typically energies between 300 and 1000 eV) and deposited atoms results in a distinct texture depending on the parameters used. The deposited layers were successfully used as textured templates for functional materials as for example superconducting or hard magnetic thin films.

The IBAD approach is investigated in our group for more than a decade using ion-beam assisted pulsed laser deposition. Whereas the focus in the beginning was on materials like YSZ or Pr6O11 showing a texture alignment with increasing thickness, recent activities are concentrated on materials with a rocksalt structure like MgO or transition metal nitrides. Reflection high energy electron diffraction (RHEED) is used in-situ as a surface sensitive method to study the texture development in detail. As an example, IBAD-TiN reveals a cube texture on amorphous substrates immediately after nucleation in films below 10 nm (Fig. 2). Homoepitaxial growth without ion-beam assistance was used to further increase the film thickness leading to highly textured templates.

Highly cube textured TiN layers were used to realise different buffer architecture for YBCO coated conductors based on the IBAD approach. An electrically conducting and amorphous Ta-Ni seed layer was successfully applied for conducting buffer architectures. High Jc values on polished stainless steel tapes were achieved with a simplified buffer layer stack based on IBAD-TiN. In the last years we could show for the first time that also other transition metal nitrides with a rocksalt structure as NbN or ZrN can be textured in a similar way during nucleation using a reactive deposition process. As a result, highly textured NbN films with an in-plane alignment down to 4° were grown on amorphous substrates using this approach.

selected publications:

R. Gärtner, R. Hühne, J. Engelmann, J. Hänisch, R. Kaltofen, S. Oswald, L. Schultz, B. Holzapfel
High-Jc YBCO coated conductors based on IBAD-TiN using stainless steel substrates
IEEE Trans. Appl. Supercond. 21 (2011) 2920-2923

M. Kidszun, R. Hühne, B. Holzapfel, L. Schultz
Ion beam assisted deposition of textured NbN thin films
Supercond. Sci. Technol. 23 (2010) 025010

R. Hühne, K. Güth, R. Gärtner, M. Kidszun, F. Thoss, B. Rellinghaus, L. Schultz, B. Holzapfel
Application of textured IBAD-TiN buffer layers in coated conductor architectures
Supercond. Sci. Technol. 23 (2010) 014010

K. Güth, R. Hühne, V. Matias, J. Rowley, T. Thersleff, L. Schultz, B. Holzapfel
Preparation of conductive buffer architectures based on IBAD-TiN
IEEE Trans. Appl. Supercond. 19 (2009) 3447-3450

Hühne, R., Fähler, S., Holzapfel, B.
Thin biaxially textured TiN films on amorphous substrates prepared by ion-beam assisted pulsed laser deposition
Appl. Phys. Lett. 85 (2004) 2744-2746

Hühne, R., Beyer, Ch., Holzapfel, B., Oertel, C.-G., Schultz, L., Skrotzki, W.
Formation and destruction of cube texture in MgO films using ion-beam assisted pulsed laser deposition
J. Appl. Phys. 90 (2001) 1035-1039