Structural and Magnetic Properties of Nitrogen Acceptor Co-doped (Zn,Fe)Te Thin Films Grown in Zn-Rich Condition by Molecular Beam Epitaxy (MBE)

• Published in: Journal of electronic materials Vol. 49; no. 10; pp. 5739 - 5749
• Main Authors: Saha, Indrajit, Tomohiro, Yuta, Kanazawa, Ken, Nitani, Hiroaki, Kuroda, Shinji
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.10.2020; Springer Nature B.V
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Doped films; Electronics and Microelectronics; Epitaxial growth; Ferromagnetic materials; Fine structure; Instrumentation; Magnetic properties; Magnetism; Magnetization; Magnetization curves; Materials Science; Molecular beam epitaxy; Nitrogen; Optical and Electronic Materials; Paramagnetism; Precipitates; Room temperature; Solid State Physics; Structural analysis; Superconducting quantum interference devices; Thin films; Valence; X ray absorption; Zinc; Molecular beam epitaxy; tellurides; room temperature ferromagnetism; magnetic materials
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-020-08311-7

We have investigated the structural and magnetic properties of (Zn,Fe)Te:N thin films grown under Zn-rich condition with Fe composition fixed at 1.4% and N concentrations varying in the range [N] = 1.8 × 10 18 –5.1 × 10 19  cm −3 . Structural analysis by x-ray diffraction (XRD) detects some additional extrinsic diffraction peaks possibly from Fe-N compounds in the N-doped film with [N] = 5.1 × 10 19  cm −3 only. Accordingly, x-ray absorption fine structure (XAFS) analysis reveals the shifting of Fe atoms from substitutional position for N-doped films with high N concentrations, [N] ≥ 1.8 × 10 19  cm −3 , whereas N-doped films with intermediate N concentrations [N] ≤ 4.3 × 10 18  cm −3 are composed of pure diluted phase with substitutional Fe atoms in the valence state deviating from Fe 2+ . Magnetization measurement using SQUID confirms drastic change of magnetic properties; the linear dependence of magnetization on magnetic field, typical of van Vleck-type paramagnetism in the film without N-doping changes into room temperature ferromagnetic behaviors with hysteretic magnetization curves for N-doped films. The observed weak room temperature ferromagnetic behavior of the N-doped films with [N] ≤ 4.3 × 10 18  cm −3 may reflect the deviation of substitutional Fe valence state from Fe 2+ to Fe 2+/3+ mixed states. On the other hand, the robust room temperature ferromagnetic behavior exhibited by N-doped films with [N] ≥ 1.8 × 10 19  cm −3 may originate from precipitates of Fe-N compounds with Fe being in Fe 2+/3+ or other valence state.