Surface roughness and surface-induced resistivity of gold films on mica: influence of roughness modelling

Abstract

We report measurements of the temperature dependent resistivity ρ(T ) of a gold film 70 nm thick deposited on mica preheated to 300 • C in UHV, performed between 4 K and 300 K, and measurements of the surface topography of the same film performed with a scanning tunnelling microscope (STM). From the roughness measured with the STM we determine the parameters δ (r.m.s. amplitude) and ξ (lateral correlation length) corresponding to a Gaussian and to an exponential representation of the average autocorrelation function (ACF). We use the parameters δ and ξ determined via STM measurements to calculate the quantum reflectivity R, and the temperature dependence of both the bulk resistivity ρ 0 (T ) and of the increase in resistivity ρ(T ) = ρ(T ) − ρ 0 (T ) induced by electron-surface scattering on this film, according to a modified version of the theory of Sheng, Xing and Wang recently proposed (Munoz et al 1999 J. Phys.: Condens. Matter 11 L299). The resistivity ρ 0 in the absence of surface scattering predicted for a Gaussian representation of the ACF is systematically smaller than that predicted for an exponential representation of the ACF at all temperatures. The increase in resistivity ρ induced by electron-surface scattering predicted for a Gaussian representation of the average ACF data is about 25% larger than the increase in resistivity predicted for an exponential representation of the ACF data.

Interference between bulk and boundary scattering in high quality films

“…Currently, we are aware of only one group which accompanies the measurements of the interplay between electron-phonon and roughness scattering channels as a function of temperature by the simultaneous analysis of surface roughness. 14,26 It is instructive to compare our semianalytical quasiclassical results with previous quantum computations which explicitly include QSE. 4,5,8,10 Reference 4 does not contain any explicit equations for the interference terms that can be compared with our results, especially in the quasiclassical regime.…”

Beams of gravitationally bound ultracold neutrons in rough waveguides

“…The correlation function ψ (y) not only affects directly, via the integral (34), but it also can distort the experimental measurements of the amplitude and the correlation radius of surface inhomogeneities η and r. The result of the STM study of a rough metal surface in Ref. [16] showed that the values of η and r were vastly different depending on whether the same STM data were fitted using the Gaussian or simple exponential correlation function. This result is even more surprising taking into account the fact that both of these correlation functions, in contrast to the power-law correlators, have well-defined values of the correlation radius and the roughness amplitude.…”

“…There are many other realistic forms of the correlation function that differ from each other by the rate of decay of the correlator in real or Fourier space [14][15][16]. Below, in addition to the Gaussian correlator, we will investigate two major classes of the correlation functions following Ref.…”

“…For example, a fit of the scanning tunneling microscopy (STM) data by the Gaussian (9) and exponential (14) correlators (λ = 1/2) in Ref. [16] showed that both could account for the measured roughness profile. However, the sets of values of the average amplitude of roughness and the correlation radius R, which were extracted from the fit of the experimental profile to these two correlators, were significantly different.…”

Electrical and optical properties dependence on evolution of roughness and thickness of Ga:ZnO films on rough quartz substrates

“…Many papers have proved that the electrical and optical properties of thin films depend explicitly on the film thickness, the RMS roughness w, the lateral correlation length ξ(t), and the roughness exponent α [10][11][12][13]. However, little work has been done in the studies of the morphological roughness evolutions in the GZO film growth.…”