DENSITY OF STATES OF ALAS/GAAS FRACTIONAL LAYER SUPERLATTICE QUANTUM WIRES IN A MODULATION DOPED STRUCTURE

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 quantum wires is 8 nm and the width is 0.25-mu-m. 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.