Paper EH-ThM11
Transition Metals Ion Implantation into AlInN/GaN Thin Films
Thursday, December 11, 2014, 11:20 am, Room Lehua
| Session: |
Nanotechnology & Energy |
| Presenter: |
Abdul Majid, University of Gujrat, Pakistan |
| Authors: |
A. Majid, University of Gujrat, Pakistan
Zhu, Chinese Academy of Sciences, Beijing
|
| Correspondent: |
Click to Email |
A lot of work has been done on Mn doping in III-V [1] but work on Mn and other TM ions doping in AlInN is still lacking. Out of III-Nitrides, AlInN is the only ternary alloy which is capable of lattice matching with GaN and is potential candidate for use as distributed Bragg reflectors, cladding layers and several other electronic /optoelectronic devices[2]. Like several other materials, the doping of AlInN with TM elements is expected to produce diluted magnetic semiconductors (DMS) based on it. Realization of AlInN based DMS will be exciting due to wide direct band gap and lattice matching capability at 17% indium content with GaN. This work is one of initial detailed reports on TM doping into AlInN. Transition metals ions of Cr, Mn, Co and V were implanted MOCVD grown wurtzite AlInN/GaN thin films at doses 5x1014 to 5x1015 and 5x1016 ions/cm2. The structural properties of the materials were studied by X-ray diffraction and Rutherford backscattering spectroscopy (RBS) techniques. XRD analysis revealed that GaN related peak for all samples remains at its usual Bragg position of 2θ=34.56o whereas a shift in AlInN peak taken place from its position of 2θ=35.51o for as-grown sample. RBS analysis provided interesting results with clear shift in position of indium related peak pointing to migration of indium atoms towards interface of hetrostructures. Moreover this peak has observed to be splitted into two peaks which is indication of depth wise re-distribution of indium atoms within the material. The measurements of magnetization versus temperature as well as applied magnetic field measured using SQUID magnetometer indicated room temperature ferromagnetism in the films. The density Functional Theory based calculations of Transition metals doped AlInN predicted that TM ions will preferably substitute In sites in the alloy. In order to model the experimental results and explore the mechanism of ferromagnetic exchange interactions in the materials, detailed density functional theory (DFT) based calculations were performed. The electronic and structural properties of pure and TM doped AlInN were computationally investigated using ADF-BAND program which performs calculations using Kohn-Sham under Local Density Approximation. We modeled 64 atoms supercell with 3x3x3 mesh in the form Al27In5N32 for pure AlInN and Al27In3Mn2N32 (2 Mn atoms substitutes 2 In atoms), Al26In5Mn1N32 (Mn substitutes Al) and Al26In5Mn1N32 (Mn substitutes Al) supercells for Mn doped AlInN. The literature suggests that Fermi level should lie within spin up Mn band predicting Mn:AlInN to be in half metallic state like other Mn doped III-Nitrides [3]. The calculated results indicate that Mn d band is partially filled for Al27In4Mn1N32 and Al27In3Mn2N32 whereas completely empty for Al26In5Mn1N32. It can be said that, either one or two Mn atoms substituting In sites produces expected half metallic AlInN whereas Mn substituting Al sites turns out to be unacceptable option. It is therefore concluded that Mn will preferably substitute indium in AlInN.
[1]. T. C. Schulthess, W. M. Thmmerman, Z. Szotek, W. H. Buler and G. M. Stocks, Nature materials, 4, 838 (2005)
[2]. A. Majid, G. Husnain, M. Usman, A. Shakoor, N. Hassan, J.J. Zhu, Physics Letters A 377, 2986 (2013)
[3]. T. Jungwirth, Jairo Sinova, J. Mašek, J. Kučera and A. H. MacDonald, Rev. Mod. Phys. 78, 809 (2006)