Growth and electrical characterization of Al0.24Ga0.76As/AlxGa1-xAs/Al0.24Ga0.76As modulation-doped quantum wells with extremely low x

TL;DR

This paper reports the growth and electrical analysis of ultra-low aluminum mole fraction quantum wells, revealing alloy scattering as a key mobility-limiting factor in high-purity 2DEGs for fractional quantum Hall studies.

Contribution

It presents the first detailed electrical characterization of AlGaAs quantum wells with extremely low aluminum content, highlighting alloy disorder effects.

Findings

Alloy scattering rate of 24 ns^-1 per %Al at zero magnetic field

Alloy scattering dominates mobility limitations at x=0.00057

Quantum wells enable studies of fragile fractional quantum Hall states

Abstract

We report on the growth and electrical characterization of modulation-doped Al0.24Ga0.76As/AlxGa1-xAs/Al0.24Ga0.76As quantum wells with mole fractions as low as x=0.00057. Such structures will permit detailed studies of the impact of alloy disorder in the fractional quantum Hall regime. At zero magnetic field, we extract an alloy scattering rate of 24 ns-1 per %Al. Additionally we find that for x as low as 0.00057 in the quantum well, alloy scattering becomes the dominant mobility-limiting scattering mechanism in ultra-high purity two-dimensional electron gases typically used to study the fragile nu=5/2 and nu=12/5 fractional quantum Hall states.