SIMS study of effect of Cr adhesion layer on the thermal stability of silver selenide thin films on Si Bhaskar Chandra Mohanty a , A.K. Tyagi b , A.K. Balamurugan b , Shikha Varma c , S. Kasiviswanathan a, * a Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India b Materials Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, India c Institute of Physics, Bhubaneswar 751005, India Received 22 September 2007; received in revised form 20 November 2007 Available online 3 January 2008 Abstract Effect of heat treatment on silver selenide films grown from diffusion-reaction of Ag and Se films on Cr-buffered Si substrates was investigated up to 400 °C. X-ray diffraction (XRD), Scanning electron microscopy (SEM), Secondary ion mass spectrometry (SIMS) and X-ray photoelectron spectroscopy (XPS) were used to characterize the films. XRD patterns of the films showed stress assisted change in preferential orientation of the films upon annealing: the films annealed at 200 °C exhibited a strong orientation along (2 0 0) plane, which changed to (0 1 3) after annealing at 300 and 400 °C. Dynamic SIMS measurements showed that Cr is confined to the interface and that there is no diffusion of Cr into silver selenide. Ó 2007 Elsevier B.V. All rights reserved. PACS: 61.05.cp; 82.80.Ms; 68.60.Dv Keywords: Silver selenide; XRD; SIMS; XPS 1. Introduction Silver selenide, which has long been known for its poly- morphism and high ionic conductivity [1], is being studied with renewed interest after the recent reports of huge mag- netoresistance in this material [2]. This observation assumes further significance as both Ag and Se are non- magnetic and stoichiometric silver selenide does not exhibit significant magneto-resistance. In addition, the linear dependence of magneto-resistance on magnetic field makes it a promising material for magnetic field sensors. In a pre- vious paper [3], we have studied in detail the stability of sil- ver selenide films grown on Si substrates, by the reaction of sequentially deposited Ag and Se thin films. However, our results showed that although the sequential deposition offered a simple way to grow thin films of silver selenide, the film morphology became unstable and agglomerated when annealed beyond 200 °C. Adhesion of a thin film to a specific substrate is a key factor that determines dewetting and agglomeration of a uniform film during thermal processing. One of the effec- tive methods to improve the adhesion of, for instance, a noble metal film to an oxide substrate is to insert a suitable layer between the metal film and the substrate [4]. Tradi- tionally refractory metals such as Cr and Ti and their com- pounds have been employed for this purpose. The ability of these adhesion promoters to inhibit agglomeration has been attributed to their tendency to easily form sub-oxides, especially during the initial stages of growth. This enhances the adhesion as the oxide–oxide bond is shown to be much stronger than the noble metal-oxide bond. Additionally, the adhesion films do not easily diffuse into or undergo a chemical reaction with the metal films. The present work 0168-583X/$ - see front matter Ó 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.nimb.2007.11.029 * Corresponding author. Fax: +91 44 22570509. E-mail address: kasi@iitm.ac.in (S. Kasiviswanathan). www.elsevier.com/locate/nimb Available online at www.sciencedirect.com Nuclear Instruments and Methods in Physics Research B 266 (2008) 1480–1485 NIM B Beam Interactions with Materials & Atoms