Random Berry phase magnetoresistance as a probe of interface roughness in Si MOSFET’s

Abstract

The effect of silicon-oxide interface roughness on the weaklocalization magnetoconductance of a silicon MOSFET in a magnetic field, tilted with respect to the interface, is studied. It is shown that an electron picks up a random Berry's phase as it traverses a closed orbit. Effectively, due to roughness, the electron sees an uniform field parallel to the interface as a random perpendicular field. At zero parallel field the dependence of the conductance on the perpendicular field has a well known form, the weak-localization lineshape. Here the effect of applying a fixed parallel field on the lineshape is analyzed. Many types of behavior are found including homogeneous broadening, inhomogeneous broadening and a remarkable regime in which the change in lineshape depends only on the magnetic field, the two length scales that characterize the interface roughness and fundamental constants. Good agreement is obtained with experiments that are in the homogeneous broadening limit. The implications for using weak-localization magnetoconductance as a probe of interface roughness, as proposed by Wheeler and coworkers, are discussed.

Experimental study of weak antilocalization effects in a high-mobilityInxGa1−xAStudenikin1, Coleridge2, Ahmed3 et al. 2003Phys. Rev. B758570View full textAdd to dashboardCite

“…The saturation below 1K suggests some additional phase-breaking mechanisms limit τ ϕ . Possibilities include inhomogeneous distribution of alloy composition, interface roughness or doping concentration variations 18,20,22 . In high mobility samples such as that studied here small fluctuating magnetic fields may also be playing a role.…”

Weak field magnetoresistance of narrow-gap semiconductor InSb

“…According to Mathur and Baranger's work, 8 the mechanism for the influence of roughness on magnetoresistance is due to microroughness. The in-plane uniform magnetic field is then equivalent to a random perpendicular magnetic field due to the microroughness.…”

“…In the second category the magnetoresistance curves in tilted magnetic field don't collapse into those in perpendicular field. This non-trivial anisotropy has been identified and systematically studied in quantum well systems, [4][5][6][7] MOSFET 8 and a few films. [9][10][11] Two mechanisms have been proposed as possible explanations for this anisotropy.…”

“…[9][10][11] Two mechanisms have been proposed as possible explanations for this anisotropy. One is the random Berry phase induced by in-plane field-the roughness effect; 4,8 the other is a mixing of singlet and triplet Cooperon due to Zeeman coupling-the Zeeman mechanism. [4][5][6][7] There have been quite few researches concerning the anisotropy of magnetoresistance in thin films and the mostly anisotropy investigated is in pure weak localization effect.…”

Anisotropic positive magnetoresistance of a nonplanar 2D electron gas in a parallel pagnetic field

“…This results in the four combinations of the 2D electron-gas magnetoresistance along the [110] and [110] directions. It should be noted that, in the temperature range from 4.2 to 1.6 K, the positive magnetoresistance observed in the structures under study did not vary, evidencing its classical [9,10] rather than quantummechanical nature [11][12][13].…”