Growth parameter dependence of structural, electrical and magnetic properties in GaGdN layers grown on GaN(0001)

• Published in: Journal of crystal growth 2013-09, Vol.378, p.314-318
• Main Authors: Sano, S., Hasegawa, S., Mitsuno, Y., Higashi, K., Ishimaru, M., Sakurai, T., Ohta, H., Asahi, H.
• Format: Article
• Language: English
• Subjects: A1. X-ray diffraction; A3. Molecular beam epitaxy; B1. Nitrides; B2. Magnetic material; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross sections; Cross-disciplinary physics: materials science; rheology; Crystal growth; Exact sciences and technology; Fluxes; Gallium nitrides; Magnetic properties; Magnetic properties and materials; Materials science; Methods of crystal growth; physics of crystal growth; Methods of deposition of films and coatings; film growth and epitaxy; Molecular beam epitaxy; Molecular, atomic, ion, and chemical beam epitaxy; Nanoparticles; Nanoscale materials and structures: fabrication and characterization; Other ferromagnetic metals and alloys; Other topics in nanoscale materials and structures; Physics; Precipitates; Studies of specific magnetic materials; Theory and models of crystal growth; physics of crystal growth, crystal morphology and orientation
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2012.12.106

The growth parameter dependence of structural, electrical and magnetic properties in Gd-doped GaN layers grown by plasma-assisted molecular beam epitaxy has been investigated. The structural and magnetic properties of Gd-doped GaN films grown on GaN templates strongly depend on the MBE growth condition. While Gd-doped GaN grown under relatively high Ga fluxes consist of wurtzite GaGdN layers without Gd-related precipitates, Gd-incorporated GaN films grown under low Ga fluxes contain a lot of nanoparticles ranging from several nm to several tens nm in size. The samples with Gd-related nanoparticles exhibit hysteresis in the magnetization–magnetic field curves at 10K. The separation between the field-cooled and zero-field-cooled magnetization–temperature curves is observed at around 30K. This behavior is understood in terms of super-paramagnetism originating from the ferromagnetic nanoparticles observed in the cross-sectional transmission electron microscopy images. ► Gd-doped GaN thin films were grown by varying Ga BEP using PA-MBE. ► Gd-doped GaN films grown under low Ga fluxes contain a lot of nanoparticles. ► Gd-doped GaN films grown under low Ga fluxes have super-paramagnetic property.