The origin of the large perpendicular magnetic anisotropy constant K u obtained in Co 3 Pt alloy thin films is discussed in connection with a superlattice structure. The K u and the order parameter S are influenced not only by substrate deposition temperature T s but also deposition rate ␥. For T s ϭ330°C, K u and S increase with lowering ␥, whereas for T s ϭ400°C, the opposite trend is found. A model, in which the origin of K u results from two mechanisms: Magnetocrystalline anisotropy in Co 3 Pt disordered phase and interface-induced magnetic anisotropy in Co 3 Pt ordered phase, can account for the observed dependence of K u on S.
Crystallographic defects revealed by synchrotron white beam x-ray topography, electron beam induced current, optical microscopy, and electroluminescence are correlated with the electrical characteristics of medium-voltage epitaxial 4H-silicon carbide diodes. Diodes that include macroscopic crystallographic defects show a significantly reduced reverse breakdown voltage with typical microplasma current fluctuations under reverse bias. Microplasma current paths are revealed by increased electroluminescence both under forward and reverse bias of the diodes and coincide with the locations of screw dislocations in the epitaxial layers of the diodes. The role of crystallographic imperfections on the formation of stacking faults responsible for the degradation of bipolar silicon carbide components is discussed.
Epitaxially-grown Al-doped 4H-SiC has been studied by scanning spreading resistance microscopy. The measured current shows good quantitative agreement with the chemical Al concentration in the range 2×1016 to 2×1020 atoms cm−3. Simulations of the sample temperature distribution using finite element calculations predict a maximum temperature exceeding 750 K within 100 nm of the contact region at 7.5 V dc bias for an Al doping of 1020 cm−3. The heating causes a significant increase in the ionization of the dopants relative to that at room temperature. Due to the strong voltage dependence, the effect can be avoided by operating below 5 V dc bias where the temperature rise is shown to be negligible for all dopant concentrations.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.