AVS 51st International Symposium
    Semiconductors Monday Sessions
       Session SC+MI-MoM

Paper SC+MI-MoM5
Structural Characterization of GaMnN Thin Films Grown by Chemical Beam Epitaxy (CBE).

Monday, November 15, 2004, 9:40 am, Room 304B

Session: Dilute Magnetic and Ferromagnetic Semiconductors
Presenter: L.A. Carreno, University of Houston
Authors: L.A. Carreno, University of Houston
C. Boney, University of Houston
A. Bensaoula, University of Houston
Z. Zhang, University of Houston
Correspondent: Click to Email
Diluted magnetic semiconductors (DMS) based on Mn doped GaN are intensively investigated for their potential spintronics applications. Ferromagnetism has been demonstrated in Mn-doped implanted p-type GaN, Mn-diffused GaN, and n-type films of GaMnN grown by MBE. Two approaches to understanding the magnetic properties of DMS materials are pursued: one considers these materials as more-or-less random alloys; the second one considers the magnetic atoms forming small clusters that produce the observed ferromagnetism. To clarify these issues we have performed structural analysis of GaMnN thin films grown by CBE using two in-situ time of flight (TOF) ion spectroscopy techniques combined with SARIC trajectory simulations. These were complemented with ex-situ XRD, PL, Raman spectroscopy, and Backscattering/ channeling combined with PIXE. GaMnN has been grown using TEG, NH@sub 3@, and solid Mn on sapphire/GaN templates prepared by CBE and MBE. Evolution of the stress for the as grown and annealed thin films has been studied by XRD and Raman. Samples grown on sapphire/GaN templates prepared by CBE show n-type conductivity, those grown on MBE GaN templates are highly resistive. The reactor is fitted with two in-situ TOF techniques, Direct Recoil Spectroscopy (DRS) and Mass Spectroscopy of Recoiled Ions. For structural characterization, azimuthal DRS scans are used to extract the surface periodicity and from that construct models of GaMnN surfaces. Simulations of scattering and recoiling scans for GaMnN surfaces have been performed for different possible lattice locations of Mn in GaN. Similar experiments were performed using Rutherford backscattering/channeling combined with particle induced X-ray emission. DRS confirmed retention of wurtzite crystal structure obtained by RHEED and XRD for Mn concentrations up to 2.5%. Although results have shown mainly substitutional incorporation of Mn atoms at Ga sites, DRS scans also show presence of Mn atoms at interstitial positions.