Conduction in Small Localized 2D Systems

Abstract

Studies have been made of two types of small localized 2D systems on silicon surfaces. In one type the samples were long (~12 μm) and narrow (~0.05 μm). These samples showed variable range (1D) hopping above about 300 mK. Below strong structure occurs as a function of chemical potential because of the small number of states within 10 kT (10-100). Because single hops are involved, conduction in the peaks is simply activated and rectifying. The second type of sample was short (0.5 μm) and conduction was dominated by tunnelling at low temperatures (<200 mK). The peaks observed did not vary in width or length below about 80 mK but broadened and decreased at higher temperatures as expected of tunneling. Temporal fluctuations and substructure were seen that might reasonably be caused by fluctuations in the occupation of other sites. The long samples were studied with R A Webb, J Wainer and A Hartstein. The tunneling samples were studied with G Timp, R A Webb and J Wainer.