Copper-doped titanium oxynitride (TiN x O y ) thin films were grown by atomic layer deposition (ALD) using the TiCl 4 precursor, NH 3 , and O 2 at 420 °C. Forming gas was used to reduce the background oxygen concentration and to transfer the copper atoms in an ALD chamber prior to the growth initiation of Cu-doped TiN x O y . Such forming gas-mediated Cu-doping of TiN x O y films had a pronounced effect on their resistivity, which dropped from 484 ± 8 to 202 ± 4 μΩ cm, and also on the resistance temperature coefficient (TCR), which decreased from 1000 to 150 ppm °C−1 . We explored physical mechanisms causing this reduction by performing comparative analysis of atomic force microscopy, X-ray photoemission spectroscopy, X-ray diffraction, optical spectra, low-temperature transport, and Hall measurement data for the samples grown with and without forming gas doping. The difference in the oxygen concentration between the films did not exceed 6%. Copper segregated to the TiN x O y surface where its concentration reached 0.72%, but its penetration depth was less than 10 nm. Pronounced effects of the copper doping by forming gas included the TiN x O y film crystallite average size decrease from 57−59 to 32−34 nm, considerably finer surface granularity, electron concentration increase from 2.2(3) × 10 22 to 3.5(1) × 10 22 cm −3 , and the electron mobility improvement from 0.56(4) to 0.92(2) cm 2 V −1 s −1 . The DC resistivity versus temperature R(T) measurements from 4.2 to 300 K showed a Cu-induced phase transition from a disordered to semimetallic state. The resistivity of Cu-doped TiN x O y films decreased with the temperature increase at low temperatures and reached the minimum near T = 50 K revealing signatures of the quantum interference effects similar to 2D Cu thin films, and then, semimetallic behavior was observed at higher temperatures. In TiN x O y films grown without forming gas, the resistivity decreased with the temperature increase as R(T) = − 1.88T 0.6 + 604 μΩ cm with no semimetallic behavior observed. The medium range resistivity and low TCR of Cu-doped TiN x O y make this material an attractive choice for improved matching resistors in RF analog circuits and Si complementary metal−oxide−semiconductor integrated circuits.

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A top-down nanofabrication approach was used to obtain silicon nanowires from silicon-on-insulator wafers using direct-write electron beam lithography and plasma-reactive ion etching. Fabricated with designed pattern silicon nanowires are 0.4, 0.8, 2 μm in width and 100 nm in height. The devices can be applied in future medical diagnostic applications as novel biosensors with detection principle based on the changes in electrical characteristics of the silicon nanowires functionalized with thiol-containing molecules.

We fabricated Cu-doped TiNxOy thin film resistors by using atomic layer deposition, optical lithography, dry etching, Ti/Cu/Ti/Au e-beam evaporation and lift-off processes. The results of the measurements of the resistance temperature dependence, non-linearity, S-parameters at 0.01–26 GHz and details of the breakdown mechanism under high-voltage stress are reported. The devices’ sheet resistance is 220 ± 8 Ω/□ (480 ± 20 µΩ*cm); intrinsic resistance temperature coefficient (TCR) is ~400 ppm/°C in the T-range of 10–300 K; and S-parameters versus frequency are flat up to 2 GHz with maximum variation of 10% at 26 GHz. The resistors can sustain power and current densities up to ~5 kW*cm−2 and ~2 MA*cm−2, above which they switch to high-resistance state with the sheet resistance equal to ~200 kΩ/□ (~0.4 Ω*cm) caused by nitrogen and copper desorption from TiNxOy film. The Cu/Ti/TiNxOy contact is prone to ageing due to gradual titanium oxidation while the TiNxOy resistor body is stable. The resistors have strong potential for applications in high-frequency integrated and hybrid circuits that require small-footprint, medium-range resistors of 0.05–10 kΩ, with small TCR and high-power handling capability.

In this work we show a preparation technique of Co2FeSi full-Heusler alloy thin films on silicon-on-insulator (SOI) substrates, employing rapid thermal annealing (RTA). The films of the Co2FeSi alloy were formed by a silicidation reaction, caused by RTA, between the ultrathin SOI (001) layer and the Fe/Co layers deposited on it. It is assumed that this technology is compatible with the process of formation of a half-metal source-drain in an advanced CMOS and SOI technology and will be applicable for the manufacture of a source-drain of a field-effect transistor. Schottky barrier field-effect transistors (FET) with a back-gate, based on silicon nanowires with source and drain of a Co2FeSi film, synthesized on an SOI substrate, were manufactured. The transport properties of the device were investigated.

In this work, we studied the electronic transport properties of silicon nanowire field-effect transistors with a back gate. A nontrivial magnetic field influence on the drain current at low temperature (10 K) was found. The strongest effect was observed in the majority carrier accumulation mode. In this mode magnetic field of 0.5 T increases current through the device by more than an order of magnitude. The paper describes the possible mechanisms of the magnetic field influence on the electronic transport characteristics of the structures.

Three-layer iron-rich Fe3+xSi1−x/Ge/Fe3+xSi1−x (0.2 < x < 0.64) heterostructures on a Si(111) surface with Ge thicknesses of 4 nm and 7 nm were grown by molecular beam epitaxy. Systematic studies of the structural and morphological properties of the synthesized samples have shown that an increase in the Ge thickness causes a prolonged atomic diffusion through the interfaces, which significantly increases the lattice misfits in the Ge/Fe3+xSi1−x heterosystem due to the incorporation of Ge atoms into the Fe3+xSi1−x bottom layer. The resultant lowering of the total free energy caused by the development of the surface roughness results in a transition from an epitaxial to a polycrystalline growth of the upper Fe3+xSi1−x. The average lattice distortion and residual stress of the upper Fe3+xSi1−x were determined by electron diffraction and theoretical calculations to be equivalent to 0.2 GPa for the upper epitaxial layer with a volume misfit of −0.63% compared with a undistorted counterpart. The volume misfit follows the resultant interatomic misfit of |0.42|% with the bottom Ge layer, independently determined by atomic force microscopy. The variation in structural order and morphology significantly changes the magnetic properties of the upper Fe3+xSi1−x layer and leads to a subtle effect on the transport properties of the Ge layer. Both hysteresis loops and FMR spectra differ for the structures with 4 nm and 7 nm Ge layers. The FMR spectra exhibit two distinct absorption lines corresponding to two layers of ferromagnetic Fe3+xSi1−x films. At the same time, a third FMR line appears in the sample with the thicker Ge. The angular dependences of the resonance field of the FMR spectra measured in the plane of the film have a pronounced easy-axis type anisotropy, as well as an anisotropy corresponding to the cubic crystal symmetry of Fe3+xSi1−x, which implies the epitaxial orientation relationship of Fe3+xSi1−x (111)[0−11] || Ge(111)[1−10] || Fe3+xSi1−x (111)[0−11] || Si(111)[1−10]. Calculated from ferromagnetic resonance (FMR) data saturation magnetization exceeds 1000 kA/m. The temperature dependence of the electrical resistivity of a Ge layer with thicknesses of 4 nm and 7 nm is of semiconducting type, which is, however, determined by different transport mechanisms.

Herein, the AC magnetoresistance (MR) in the silicon‐on‐insulator (SOI)‐based Fe/Si/SiO2/p‐Si structure is presented. The structure is used for fabricating a back‐gate field‐effect pseudo‐metal–oxide–semiconductor field‐effect transistor (MOSFET) device. The effects of the magnetic field and gate voltage on the transport characteristics of the device are investigated. Magnetoimpedance value of up to 100% is obtained due to recharging of the impurity and surface centers at the insulator/semiconductor interface. A resistance variation of up to 1000% is found, which is caused by the voltage applied to the gate and the field effect on the band structure of the sample. Combining the magnetic and electric fields, one can either change the absolute value of the AC resistance while having the MR fixed or change the sign and character of the field dependence of the MR. The observed effects can be used in the development of magnetic‐field‐driven SOI‐based devices and high‐frequency circuits.