Transverse magnetoresistance, Hall mobility and Hall constant of thin Cu films deposited onto cleaved mica: Evidence of weak Anderson localization.

We report the resistivity of 5 Cu films approximately 65 nm thick, measured between 5 K and 290 K, and the transverse magnetoresistance and Hall effect measured at temperatures 5 K< T<50 K. The mean grain diameters are D=(8.9, 9.8, 20.2, 31.5, 34.7) nm, respectively. The magnetoresistance signal is positive in samples where D>L/2 (where L=39 nm is the electron mean free path in the bulk at room temperature), and negative in samples where D<L/2. The sample where D=20.2 nm exhibits a negative magnetoresistance at B < 2 Tesla and a positive magnetoresistance at B > 2 Tesla. A negative magnetoresistance in Cu films has been considered evidence of charge transport involving weak Anderson localization. These experiments reveal that electron scattering by disordered grain boundaries found along L leads to weak Anderson localization, confirming the localization phenomena predicted by the quantum theory of resistivity of nanometric metallic connectors. Anderson localization becomes a severe obstacle for the successful development of the circuit miniaturization effort pursued by the electronic industry, for it leads to a steep rise in the resistivity of nanometric metallic connector with decreasing wire dimensions (D<L/2) employed in the design of Integrated Circuits.

Влияние электронного и дырочного допирования на транспортные характеристики халькогенидных систем

The electrical properties and the Hall effect in semiconductor compounds Ag0.01Mn0.99S and Tm0.01Mn0.99S have been studied in the temperature range 80–400 K in a magnetic field of 12 kOe. The mechanism of conduction is established, which depends on the type of doping and concentration from the current - voltage characteristics. At the replacement of manganese by silver, the Mott type was found, and the replacement by thulium causes ohmic conductivity. The mobility and type of charge carriers are found from the Hall constant.

Features of Radiation-Defect Annealing in n-Ge Single Crystals Irradiated with High-Energy Electrons

The isothermal annealing of n-Ge single crystals irradiated with 10-MeV electrons to the fluence Φ = 5 × 1015 cm−2 has been studied. On the basis of the measured temperature dependences of the Hall constant and by solving the electroneutrality equations, the concentrations of radiation-induced defects (A-centers) in irradiated n-Ge single crystals are calculated both before and after the annealing. An anomalous increase of the Hall constant is found, when the irradiated n-Ge single crystals were annealed at Tan = 403 K for up to 3 h. The annealing at the temperature Tan = 393 K for 1 h gave rise to the np conversion in the researched crystals. The revealed effects can be explained by the concentration growth of A-centers owing to the generation of vacancies at the annealing of disordered crystal regions.

Кинетические свойства твердых растворов Mn-=SUB=-1-x-=/SUB=-Gd-=SUB=-x-=/SUB=-Se

The results of kinetic study of the Mn_1 – x Gd_ x Se chalcogenide solid solutions with different substitute concentrations (0 ≤ x ≤ 0.15) in the temperature range of 80–400 K are reported. The difference between the Hall constant and thermopower signs has been found. The electron-type conductivity determined from the Hall constant and hysteresis of the I – V characteristics have been explained by the existence of nanoareas with local electric polarizations. The sharp extrema observed in the temperature dependence of thermopower are explained by splitting of a narrow 4 f subband by the crystal field.