Limits to mobility in ultrahigh-mobility GaAs two-dimensional electron systems*

Two dimensional electron systems (2DESs) in GaAs quantum wells are some of the cleanest materials that can be grown in a lab. Continuous improvement in their quality (mobility) through advances in molecular beam epitaxy has enabled emergence of several unexpected exotic many-body phases over the past few decades. With recent interest in GaAs 2DESs due to potential applications in topological quantum computing and continued search for new interaction-driven, many-body phases, it becomes imperative to understand what limits the mobility in modern ultrahigh-mobility 2DESs. We try to answer this question by presenting experimental mobility data for a wide variety of state-of-the-art GaAs 2DESs, and analyzing various scattering mechanisms that set the limits to mobility [1]. Ultraclean GaAs 2DESs with densities ranging from ~ 0.2 to 3 x 10¹¹/cm² exhibit an interesting trend in mobility, rising with density up to a new world record of ~57 x 10⁶ cm²/Vs at a density of 1.55 x 10¹¹/cm², and then dropping. A careful comparison of experimental data and models explains the trends while providing guidelines to achieving 100 x 10⁶ cm²/Vs mobility and beyond.  

 

[1] Y. J. Chung, A. Gupta, K. W. Baldwin, K. W. West, M. Shayegan, and L. N. Pfeiffer, Phys. Rev. B 106, 075134 (2022).