Density of states of AlAs/GaAs fractional layer superlattice quantum wires in a modulation doped structure

Abstract

The density of states (DOS) of AlAs/GaAs fractional layer superlattice (FLS) quantum wires is found to consist of one-dimensional and zero-dimensional states. The FLS quantum wires are fabricated by electron beam lithography from the AlAs/GaAs FLS modulation doped heterostructure. The periodicity of the FLS quatum wires is 8 nm and the width is 0.25 μm. Drain current oscillations with negative transconductance is observed below 7.5 K due to a reduction in wire width. The density of states is estimated from the temperature dependence of the threshold voltage ( V th). Since the DOS of the FLS quantum wire structure has sharper peaks than that of the unconfined FLS modulation-doped structure, which has both one-dimensional and two-dimensional electron states, we can conclude that the additional sub-micron confinement reduces these states to zero-dimensional and one-dimensional, respectively.