Ion-beam assisted pulsed laser deposition of textured transition-metal nitride films
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Ion-beam assisted pulsed laser deposition of textured transition-metal nitride films Ruben Hühne, Martin Kidszun, Konrad Güth, Franziska Thoss, Bernd Rellinghaus, Ludwig Schultz and Bernhard Holzapfel IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, D-01171 Dresden, Germany
ABSTRACT Ion-beam assisted deposition (IBAD) offers the possibility to prepare thin textured films on amorphous or non-textured substrates. It was shown within the last decade that the ion beam influences the nucleation in material with a rocksalt structure leading to a strong cube texture already within the first 10 nanometres. Among these materials, transition metal nitrides exhibit interesting physical properties as superconductivity, metallic behaviour or superior hardness. Therefore, a reactive IBAD process was applied for the preparation of highly textured transition metal nitride layers using pulsed laser deposition of pure metals in combination with a nitrogencontaining ion beam. The results on the in-plane textured growth of TiN are promising for the development of conducting buffer layer architectures for YBCO coated conductors based on the IBAD approach. Furthermore, this approach was used to prepare other highly textured transition metal nitride thin films like NbN and ZrN. INTRODUCTION It was shown within the last decade that highly textured MgO films can be prepared on amorphous or nanocrystalline seed layers using ion beam assisted deposition (IBAD) [1-3]. The ion beam influences the nucleation leading to a strong cube texture within the first 10 nanometres. The axis of the grown film is aligned parallel to the ion beam in these materials, if an ion incidence angle of 45° is used relative to the substrate normal. More recently it was found that other materials with a rocksalt structure, for example TiN or NbN, can be textured in a similar way [4,5]. This phenomenon has been explained by an anisotropy of either sputter yield or radiation damage, which favours the nucleation of grains with a defined orientation relationship towards the ion beam [6-8]. In most cases, the texture changes from the desired (100)[001] cube texture to texture components with a direction parallel to the ion beam with increasing film thickness [3]. However, the cube textured layers can be stabilized to a higher film thickness using homoepitaxial growth without ion-beam assistance in order to use the films as templates for functional materials [1,4,9]. This paper summarizes our present work on the preparation of IBAD-textured nitride layers. EXPERIMENT Commercially available amorphous Si3N4/Si substrates were cut to a size of 10 mm x 10 mm and introduced into a standard PLD chamber in order to prepare the nitride layers in a
reactive deposition. A Lambda Physics KrF excimer laser (λ = 248 nm) was applied to ablate pure Ti, Nb or Zr targets using laser energy densities of 2-8 J/cm2 and laser pulse repetition rates of 1-10 Hz. An rf plasma source fed with a mixture of argon and nitrogen (ratio 1:1) was used as the assisting ion b
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