Lightly-strained germanium quantum wells with hole mobility exceeding one million

TL;DR

This paper reports the creation of a lightly-strained germanium 2D hole gas with exceptionally high mobility exceeding one million, enabling advanced quantum device applications.

Contribution

It introduces a novel lightly-strained germanium heterostructure supporting high-mobility holes with tunable quantum effects, advancing quantum hardware potential.

Findings

Hole mobility exceeds 1 million cm²/Vs

Supports fractional quantum Hall effect at low density

Low disorder and small effective mass

Abstract

We demonstrate that a lightly-strained germanium channel ($\varepsilon_{//}$ = -0.41%) in an undoped Ge/Si$_{0.1}$Ge$_{0.9}$ heterostructure field effect transistor supports a 2D hole gas with mobility in excess of 1$\times$10$^{6}$ cm$^{2}$/Vs and percolation density less than 5$\times$10$^{10}$ cm$^{-2}$. This low disorder 2D hole system shows tunable fractional quantum Hall effect at low density and low magnetic field. The low-disorder and small effective mass (0.068$m_e$) defines lightly-strained germanium as a basis to tune the strength of the spin-orbit coupling for fast and coherent quantum hardware.