Localization and Electron-Electron Interaction Effects in Submicron-Width Inversion Layers

Abstract

The localization and electron-electron interaction parts of the small conductivity variation with temperature have been extracted from data obtained on narrow field-effect transistors. One-dimensional behavior is observed and is compared with measurements on the two-dimensional region of the test samples. Magnetoconductance which selectively removes the localization part of the resistance has allowed a theoretical interpretation of the total temperature dependence.PACS numbers: 71.55. Jv, 72.15.Lh, 73.40.Qv The interpretation of magnetoconductance measurements performed on two-dimensional silicon inversion layers has been a significant triumph of localization theory. 1 ' 2 By comparison with a scale set by a magnetic length l B = ^i/2eB) 1/2 9 experiments have deduced the electron diffusion length between inelastic collisional events, a quantity which previously has been difficult to measure with such directness. 3 ' 4 Concurrently, the calculation of perturbative corrections to the conductivity showed that small conductivity variations will arise of form similar to that predicted by localization considerations. The exchange and Hartree contributions making up this electronelectron interaction nearly cancel each other for the case of short-range impurity potentials applicable to inversion layers. 1 Thus, in comparison with localization the interaction effect is small. 5 In the transition from two dimensions to one dimension, 1 phase-space considerations prevent this near cancellation. Hence there is a high likelihood that both phenomena will be significant. We report observations on quasi one-dimensional silicon inversion layers where both contributions to the small conductivity changes are comparable and distinguishable by magnetoconductance measurements.Long but narrow metal-oxide-semiconductor field-effect transistors (MOSFETs) have been fabricated where the width is comparable to l in , the inelastic length. That such a structure ought to exhibit one-dimensional localization behavior can be seen by examining the theoretical expression for the weak-localization conductance applicable at a finite temperature, 6 6a = -Se 2 D an LW QX ly (Pq 2 + 1/T in rHere L and W are the length and width, respectively, of the sample, T in is the inelastic time, 1674

Spin and phase coherence lengths in InAs wires with diffusive boundary scattering

“…At B = 0 and in the absence of SOI, the quantum correction per spin channel to the two-dimensional conductivity due to time-reversed trajectories in a Q1D system can be expressed as 31,32 δ ρ…”

Disordered electronic systems

“…More recent and extensive work by White, Tinkham, Skocpol, and Flanders (1982), Masden and Giordano (1982), Skocpol, Jackel, Hu, Howard, and Fetter (1982), Wheeler, Choi, Goel, Wisnieff, and Prober (1982), and Santhanam, Wind, and Prober (1984) For a wire of cross section A, we have seen from Eqs.…”

Electron transport in laterally confined phosphorusδlayers in silicon

“…Besides directly depositing thin metal wires on nonconducting substrates, quasi-1D systems can also be realized by constricting a twodimensional electron gas ͑2DEG͒ formed in semiconductors. The Nyquist mechanism has also been observed in narrow Si inversion layers in metal-oxide-semiconductor field effect transistors ͑MOSFETs͒ 10,11 and etched GaAs/ AlGaAs heterostructures. 12 Degenerately ␦-doped Si is another 2DEG system.…”