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Hexagonal GaN (hexagonal + gan)

Distribution by Scientific Domains
Physics and Astronomy100%

Selected Abstracts

Anisotropic FMR-linewidth of triple-domain Fe layers on hexagonal GaN(0001)

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2006
M. Buchmeier
Abstract We present a ferromagnetic resonance (FMR) study of Fe films with thicknesses between 5 and 70 nm prepared by electron-beam evaporation on top of hexagonal GaN(0001). X-ray diffraction (XRD) and low-energy electron diffraction (LEED) suggest the growth in crystallographic Fe(110) domains with three different orientations. The magnetic properties have been investigated by in-plane angle-dependent FMR at frequencies between 4.5 to 24 GHz. All samples show a hexagonal in-plane anisotropy with the easy axes oriented parallel to the Fe [001] directions. The anisotropy field strength of about 8 mT reveals a bulk-like thickness dependence. Therefore, we can exclude the following origins of anisotropy: (i) interface effects because of the bulk-like thickness dependence and (ii) averaged first order cubic or uniaxial anisotropies arising from the three grain orientations because of the relative strengths. We qualitatively explain the sixfold anisotropy by spin relaxation inside the grains. The FMR linewidth versus frequency curves are linear with almost no zero-frequency offset indicating a good homogeneity of the magnetic properties over the sample area. However, the effective damping parameter , shows pronounced anisotropy and thickness dependence, with enhanced damping along the hard axes and for thicker layers. We suggest that the additional damping can be explained by two-magnon scattering at defects which are due to the triple domain structure. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Synthesis of III-nitride microcrystals using metal-EDTA complexes

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2007
Y. H. Liu
Abstract A novel method, using metal ethylenediamine tetraacetic acid (EDTA) complexes as starting materials, is proposed to synthesize III-nitride microcrystals. Ga (Zn, Ga)-EDTA·NH4 and In-EDTA·NH4 complexes were reacted with NH3 in the temperature range of 1020,1150 °C and 300,620 °C, respectively. SEM observation and X-ray diffraction patterns show that pure phase hexagonal GaN and InN are obtained. The CL peak intensity of GaN increases as the synthesis temperature increases up to 1100 °C. The dependence of CL peak intensity on Zn doping content indicates good doping control. For InN synthesis, the temperature window is very narrow and the reaction evolves from In2O3 to InN. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Lattice Location of Implanted 147Nd and 147*Pm in GaN Using Emission Channeling

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2003
B. De Vries
Abstract The lattice location of 147Nd and 147*Pm in thin-film, single-crystalline hexagonal GaN was studied by means of the emission channeling technique. The angular emission yields of ,, particles and conversion electrons emitted by the radioactive isotopes 147Nd and 147*Pm were measured using a position-sensitive detector following 60 keV room temperature implantation at a dose of 1 × 1013 cm,2 and annealing at 900 °C. The emission patterns around the [0001], [102], [101], and [113] crystal axes give direct evidence that the majority (,70%) of Nd and Pm atoms occupy substitutional Ga sites. [source]