The size effect in electroplated copper wires has been widely studied recently. However, there is no consensus on the role of various scattering mechanisms. Therefore, an in-depth analysis to reveal the origin of the size effect is needed. In this article, we study the resistivity of fine copper wires whose feature sizes shrink in two dimensions. It is shown that the residual resistivity (at 5 K) increases with decreasing wire width or height and the temperature-dependent resistivity slightly deviates from that of bulk copper. This is mainly attributed to surface scattering rather than grain boundary scattering. In fact, the influence of grain boundary scattering in these well annealed copper wires is relatively small. In addition, for copper wires with a constant height, a linear dependence of the copper resistivity on 1/width (w) or 1/cross-sectional area (A), namely ρ=ρic+c*∕w (or ρ=ρic+c**∕A), is derived from the classic surface and grain boundary scattering models and validated experimentally. In this simple description, the contributions of different scattering mechanisms, such as surface reflectivity, p, and grain boundary reflection coefficient, R, defect and impurity density, combine together in parameters of ρic and c* (or c**). Especially, c* is a good indicator of scattering strength, from which one can quantitatively analyze the impact of nonsurface scattering contribution with a reference slope of c*=32.14.

This paper reports on a detailed magnetotransport investigation of the magnetic anisotropies of (Ga,Mn)As layers produced by various sources worldwide. Using anisotropy fingerprints to identify contributions of the various higher order anisotropy terms, we show that the presence of both a [100] and a [110] uniaxial anisotropy in addition to the primary ([100] + [010]) anisotropy is common to all medium doped (Ga,Mn)As layers typically used in transport measurement, with the amplitude of these uniaxial terms being characteristic of the individual layers.PACS numbers: 75.50. Pp,75.30.Gw, An extensive comparison of anisotropies in MBE grown (Ga,Mn)As material.

Manganese doped II -IV -V 2 chalcopyrites are promising candidates for room temperature ferromagnetic semiconductors. In this category, we report a new material MgGeAs 2 : Mn for MBE growth on GaAs substrates. Firstly, we investigated the growth of MgGeAs 2 on GaAs (001) and (111)B. Stoichiometric growth conditions were established with assistance of XPS measurements. On GaAs (001), RHEED, XRD and TEM revealed phase separation with the formation of Mg 3 As 2 and columnar grains with composition modulation. On GaAs(111)B, we obtained single crystalline films of 35 nm with a smooth surface at an optimized growth temperature of 560 °C and a beam equivalent pressure ratio Mg : Ge : As = 1 : 3.1 : 800. The lattice constant of the chalcopyrite phase is nearly matched to GaAs for both (001) and (111)B growth, in contrast to the theoretical prediction of a 6.1% mismatch. With flux variations of ± 10%, Hall measurements at room temperature showed n-type conduction (n = 4 × 10 17 ~ 3 × 10 18 cm −3 ) in germanium rich samples and p-type conduction (p = 8 × 10 18 ~ 2 × 10 19 cm −3 ) in magnesium rich samples. Two ways of manganese incorporation were tried on (111)B grown MgGeAs 2 : (1) in-situ solid state reaction by annealing a manganese layer deposited on top of MgGeAs 2 and (2) co-evaporation of manganese during the host material growth. Using method (2), manganese was incorporated by replacing 20% of magnesium without structural change. RHEED and XRD did not reveal the existence of additional phases. However, the preliminary magnetization and transport measurement didn't reveal a ferromagnetic signal in these samples.