K. Ueki

Bio: K. Ueki is an academic researcher from University of Tokyo. The author has contributed to research in topics: Hall effect & Copper. The author has an hindex of 1, co-authored 1 publications receiving 19 citations.

Hall coefficient in vacuum-deposited copper films

Abstract: The dependence of the Hall coefficient RH of vacuum-deposited copper films of thickness, temperature and time was investigated by in situ observation. RH values were found to be larger than the bulk value and a thickness dependence could hardly be observed down to 100 A. The temperature dependence was appreciably larger than for bulk material, indicating the existence of the size effect predicted by Sondheimer. RH for very thin films (below 100 A) left in the vacuum system at 295°K changed with time, and the change was ascribed to the annihilation of lattice defects in the films.

Electron transport properties of thin copper films. I.

Abstract: The thickness dependence at 300 and 80 K of the electrical resistivity and its temperature coefficient, Hall coefficient, mobility, and thermoelectric power of as‐deposited and annealed thin (< 1000 A) evaporated polycrystalline copper films and films deposited at elevated temperatures have been studied. All transport parameters in carefully prepared and well‐characterized films exhibit monotonically increasing size effects with decreasing film thickness. Both annealing and deposition at elevated temperatures cause considerable reduction of the ’’apparent’’ size effects in all the transport parameters of the room‐temperature deposited films. A critical analysis of the observed size effects shows that the data in all cases depart markedly from the predictions of the Fuchs‐Sondheimer theory (and also that of the Mayadas‐Shatzkes theory which takes into account the grain boundary surface scattering). The departure from theory is different for each transport parameter. The annealing studies show that the enhanced size effects are due to the presence of a large concentration of structural defects in the films. The observed behavior may be understood by assuming the large concentration of point and/or line defects to decrease with film thickness and with annealing as well as deposition of films at elevated temperatures. The thermopower data suggest strongly that the large concentration of defects causes distortion of the Fermi surface and thereby a strong energy dependence of the mfp or relaxation time at the Fermi surface.

Size effects on the Hall constant in thin gold films

Abstract: We report the Hall constant RH, drift mobility μD, and Hall mobility μH measured at 4 K in thin gold films deposited on mica substrates, where the dominant electron scattering mechanism is electron-surface scattering. RH increases with increasing film thickness and decreases with increasing magnetic field. For high magnetic fields B≥6 T, RH turns out to be approximately independent of magnetic field, and its value is close to that of the free electron model. We use the high magnetic field values of RH to determine film thickness. This nondestructive method leads to a determination of film thickness that agrees to within 10% with the thickness measured by other techniques. The theoretical predictions, based upon the theory of Fuchs–Sondheimer and the theory of Calecki, are at variance with experimental observations.

Hall coefficient of thin films in a mean free path model

Abstract: Defining an effective relaxation time and then using the Boltzmann transport equation, analytical expressions have been derived, in the case of nearly specular scattering on external surfaces (p>or=0.5), for the Hall coefficient and conductivity in thin metallic films subjected to a transverse magnetic field. The results for moderately high magnetic field agree well with previous theoretical works; at low magnetic field the Hall coefficient in thin films is greater than the bulk value RH0 and becomes identical with RH0 in strong magnetic field. The theoretical predictions agree well with experimental data on copper and potassium thin films.

Theoretical analysis of the Hall effect in thin polycrystalline metallic films

Abstract: In polycrystalline films where three types of scattering processes (background, grainboundaries and external surfaces scatterings) are taking place at the same time an effective relaxation time is defined in the light of a three-dimensional model of grain-boundaries. Analytical expressions for the Hall coefficient and conductivity in thin polycrystalline metallic films subjected to a transverse magnetic field are then derived by using the Boltzmann transport equation. Previously published data can be theoretically interpreted in terms of the proposed model.