Limiting scattering processes in high-mobility InSb quantum wells grown on GaSb buffer systems

TL;DR

This study reports high-mobility InSb quantum wells grown on GaSb buffers, analyzing their crystalline quality, surface morphology, and electron transport properties, highlighting their potential for quantum device applications.

Contribution

It demonstrates the growth of high-quality InSb quantum wells on GaSb buffers with detailed analysis of scattering mechanisms and spin-orbit coupling, advancing nanoscale quantum device development.

Findings

Achieved electron mobilities up to 349,000 cm²/Vs at cryogenic temperatures.

Identified remote ionized impurities as the main scattering source.

Revealed high spin-orbit coupling with an effective g-factor of -38.4.

Abstract

We present molecular beam epitaxial grown single- and double-side $\delta$-doped InAlSb/InSb quantum wells with varying distances down to 50 nm to the surface on GaSb metamorphic buffers. We analyze the surface morphology as well as the impact of the crystalline quality on the electron transport. Comparing growth on GaSb and GaAs substrates indicates that the structural integrity of our InSb quantum wells is solely determined by the growth conditions at the GaSb/InAlSb transition and the InAlSb barrier growth. The two-dimensional electron gas samples show high mobilities of up to 349 000 cm$^2$/Vs at cryogenic temperatures and 58 000 cm$^2$/Vs at room temperature. With the calculated Dingle ratio and a transport lifetime model, ionized impurities predominantly remote from the quantum well are identified as the dominant source of scattering events. The analysis of the well pronounced Shubnikov$-$de Haas oscillations reveals a high spin-orbit coupling with an effective $g$-factor of $-38.4$ in our samples. Along with the smooth surfaces and long mean free paths demonstrated, our InSb quantum wells are increasingly competitive for nanoscale implementations of Majorana mode devices.