Applied Surface Science 317 (2014) 262–268 Contents lists available at ScienceDirect Applied Surface Science journal h om epa ge: www.elsevier.com/locate/apsusc Copper ion implanted aluminum nitride dilute magnetic semiconductors (DMS) prepared by molecular beam epitaxy A. Shah a,b,∗ , Jamil Ahmad b , Ishaq Ahmad c , Mazhar Mehmood b , Arshad Mahmood a , Muhammad Asim Rasheed b a National Institute of Lasers and Optronics (NILOP), PO Nilore, Islamabad, Pakistan b DMME, Pakistan Institute of Engineering and Applied Science (PIEAS), PO Nilore, Islamabad, Pakistan c Experimental Physics Lab, National Center for Physics (NCP), Islamabad, Pakistan a r t i c l e i n f o Article history: Received 7 April 2014 Received in revised form 28 July 2014 Accepted 20 August 2014 Available online 27 August 2014 Keywords: Cu + -implanted AlN Diluted magnetic semiconductor Rutherford back scattering Ferromagnetism FC/ZFC a b s t r a c t Diluted magnetic semiconductor (DMS) AlN:Cu films were fabricated by implanting Cu + ions into AlN thin films at various ion fluxes. AlN films were deposited on c-plane sapphire by molecular beam epi- taxy followed by Cu + ion implantation. The structural and magnetic characterization of the samples was performed through Rutherford backscattering and channeling spectrometry (RBS/C), X-ray diffraction (XRD), Raman spectroscopy, vibrating sample magnetometer (VSM) and SQUID. Incorporation of copper into the AlN lattice was confirmed by RBS, while XRD revealed that no new phase was formed as a result of ion implantation. RBS also indicated formation of defects as a result of implantation process and the depth and degree of damage increased with an increase in ion fluence. Raman spectra showed only E 2 (high) and A 1 (LO) modes of wurtzite AlN crystal structure and confirmed that no secondary phases were formed. It was found that both Raman modes shift with Cu + fluences, indicating that Cu ion may go to interstitial or substitutional sites resulting in distortion or damage of lattice. Although as implanted sam- ples showed no magnetization, annealing of the samples resulted in appearance of room temperature ferromagnetism. The saturation magnetization increased with both the annealing temperature as well as with ion fluence. FC/ZFC measurements indicated that the ferromagnetic effect was not related with superparamagnetic phase formation. In spite, it was due to the formation of AlN based DMS material. The Curie temperature (T C ) of the sample prepared at an ion fluence of 5 × 10 15 cm -2 and an annealing temperature of 950 ◦ C was found to lie above 340 K. © 2014 Elsevier B.V. All rights reserved. 1. Introduction A tremendous progress has been seen in the field of micro- electronics since the time integrated circuits have replaced the discrete circuit elements. A great effort has been put forward by the scientists to further improve the functionality of devices through the control of spin of electrons [1]. Microelectronic devices utilize the charge on electrons in order to perform signal processing. The performance of these devices may be greatly enhanced if both the charge as well as spin of electrons can used simultaneously [2]. This has introduced a new generation of electronic devices known as spin-electronic or spintronic devices which utilizes both the charge and spin of electrons at the same time. ∗ Corresponding author at: NILOP, Material Science, PO Nilore, Islamabad, Pakistan. Tel.: +92 51 9248671 3051; fax: +92 51 2208051. E-mail address: attaullah77@yahoo.com (A. Shah). Spintronics has emerged as a multidisciplinary field, which offers the integration of electronic, optoelectronic and magneto- electronic features on a single chip [3]. The efforts to find as well as to improve the materials for use in spintronic device applica- tions are still under progress. In this regard, III-Nitrides based dilute magnetic semiconductors (DMSs) are thought to be ideal materials for spintronic devices [4–6]. A remarkable interest has been devel- oped in AlN, a member of III-Nitrides family, due to its wide band gap and predicted high Curie temperature (T C ) when doped with suitable transition metals (TM). Kucheyev et al. [7] reported that AlN epilayer grown on sapphire substrates did not become amor- phous even when implanted with heavy ions at high doses of keV energy. In addition, AlN ensures large sp–d hybridization between the valence orbitals and the d shells of the magnetic ions due to its small lattice constant as compared to GaN. Several groups have reported their experimental as well as theoretical observations regarding the ferromagnetic-like (DMS) behavior of AlN (near or above room temperature) when doped http://dx.doi.org/10.1016/j.apsusc.2014.08.112 0169-4332/© 2014 Elsevier B.V. All rights reserved.