Materials Science and Engineering A 423 (2006) 111–115 Texture development in Ti–Si–N nanocomposite thin films R. Chandra a , Davinder Kaur b,∗ , Amit Kumar Chawla a , N. Phinichka c , Z.H. Barber d a Institute Instrumentation Centre, Indian Institute of Technology Roorkee, Roorkee 247 667, India b Department of Physics, Indian Institute of Technology Roorkee, Roorkee 247 667, India c Faculty of Science, Srinakharinwirot University, Bangkok, Thailand d Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ, UK Received 8 July 2005; received in revised form 15 September 2005; accepted 30 September 2005 Abstract Nanocomposite thin films of titanium silicon nitride were deposited by sputtering on R-plane sapphire substrates. The effects of silicon addition and negative substrate bias on the texture development of the films were studied systematically by varying the bias voltage in the range -20 to -200V. The accompanying changes in the microstructure and growth morphology of the phases in these films were investigated in detail using X-ray diffraction and a atomic force microscopy. In addition, the effect of texture on the mechanical properties of the films was also investigated using nanoindentation technique. Pure TiN films deposited without Si exhibit a strong (1 1 1) preferred orientation, while with addition of Si, the orientation of the films changes from (1 1 1) to (2 0 0). Meanwhile the surface morphology of these films changed from a pronounced columnar microstructure to a dense, fine-grained structure. The effect of negative substrate bias voltage applied during deposition also resulted in a similar change of film orientation and microstructure and leads to the increase in hardness of the films from 21 to 40GPa, respectively. © 2006 Elsevier B.V. All rights reserved. Keywords: Texture; Nanocomposite; Thin films; Ti–Si–N films 1. Introduction Hard coatings with tailored properties are increasingly impor- tant for applications in many different areas of engineering and industry such as coatings for cutting tools under dry and high speed machining conditions protective coatings for tur- bine blades and engine parts to improve their durability [1–5]. A nanocomposite coating comprises of at least two phases: a nanocrystalline phase and an amorphous phase, or two nanocrys- talline phases. The addition of the second phase not only prevents grain growth but also suppresses grain boundary sliding (for grain size <10 nm), and hence improve the mechanical prop- erties [6–10]. The hardness of these coatings can be tailored depending on the design and application. Thin films with preferential crystallographic orientation are desirable for particular applications because of their anisotropic nature. For example, the mechanical behaviour of TiN films is governed by the preferred growth orientations, since TiN is an ∗ Corresponding author. E-mail address: dkaurfph@iitr.ernet.in (D. Kaur). anisotropic material with E 100 > E 111 (where E 100 and E 111 are the elastic moduli along the [1 0 0] and [1 1 1] crystallographic directions, respectively) [11]. The preferred orientation of TiN films may be dependent upon the competition between the sur- face free energy and the strain energy [12]. By assuming that the strain energy in the film increases linearly with thickness, it has been postulated that, when the film thickness is sufficiently small, the film orientation is the result of minimization of surface energy (observed to be (1 0 0) for TiN films) [12]. However, in other work [13], an increase in internal stress from 0.3 to 2 GPa as a result of increased substrate bias voltage during film growth, resulted in a change in preferred TiN orientation from (1 1 1) to (2 0 0), also in Ref. [14] the orientation changes to (2 0 0) from (1 1 1) by varying the incident ion/metal flux ratio from 1 to ≥5 keeping N 2 + ion energy constant at ∼20 eV which suggests that the strain energy might not be the main cause for the (1 1 1) preferred orientation. In this paper Ti 1-x Si x N thin films were deposited by ionised magnetron sputter deposition (IMSD). The variations of film structure and properties as a function of Si addition and substrate bias voltage were investigated. 0921-5093/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.msea.2005.09.132