Metallic behaviour in SOI quantum wells with strong intervalley scattering

Abstract

The fundamental properties of valleys are recently attracting growing attention due to electrons in new and topical materials possessing this degree-of-freedom and recent proposals for valleytronics devices. In silicon MOSFETs, the interest has a longer history since the valley degree of freedom had been identified as a key parameter in the observation of the controversial “metallic behaviour” in two dimensions. However, while it has been recently demonstrated that lifting valley degeneracy can destroy the metallic behaviour, little is known about the role of intervalley scattering. Here, we show that the metallic behaviour can be observed in the presence of strong intervalley scattering in silicon on insulator (SOI) quantum wells. Analysis of the conductivity in terms of quantum corrections reveals that interactions are much stronger in SOI than in conventional MOSFETs, leading to the metallic behaviour despite the strong intervalley scattering.

Chapter 3 Transport in a Two-Dimensional Disordered Electron Liquid with Isospin Degrees of Freedom

“…Interaction amplitudes γs , γ t , γ v and conductivity σ xx are taken at the length scale L T = σ xx /zT . It is instructive to compare result (86) with the result for the situation when one of the quantum wells is not filled by electrons. This corresponds to the limit d → ∞.…”

“…We mention that recently 2D two-valley electron system in SiO 2 /Si(100)/SiO 2 quantum well has been experimentally studied. 85,86 However, in Ref. 86 the inter valley scattering rate was estimated to be of the order of 7 K such that 2D electron system behaves as single valley one for transport at low temperatures (T 7 K).…”

“…85,86 However, in Ref. 86 the inter valley scattering rate was estimated to be of the order of 7 K such that 2D electron system behaves as single valley one for transport at low temperatures (T 7 K).…”

Valley polarization assisted spin polarization in two dimensions

“…Experimental research into the physical consequences of valley polarizing a two-dimensional electron system in the steady state is led by studies of AlAs and Si-based structures. It has been demonstrated that valley polarization dramatically affects phenomena such as the fractional quantum Hall effect 11 12 13 14 and the metal insulator transition 15 16 17 18 , two effects in which electron–electron interactions are central. Pioneering experiments performed in AlAs indicate that valley polarization also has a strong impact on another effect where electron–electron interactions play crucial roles: spin polarization.…”