Shallow and Undoped Germanium Quantum Wells: A Playground for Spin and Hybrid Quantum Technology

Amir Sammak, Diego Sabbagh, Nico W. Hendrickx, Mario Lodari, Brian Paquelet Wuetz, Alberto Tosato, La Reine Yeoh, Menno Veldhorst, Giordano Scappucci*, More Authors

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

54 Citations (Scopus)
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Buried-channel semiconductor heterostructures are an archetype material platform for the fabrication of gated semiconductor quantum devices. Sharp confinement potential is obtained by positioning the channel near the surface; however, nearby surface states degrade the electrical properties of the starting material. Here, a 2D hole gas of high mobility (5 × 105 cm2 V−1 s−1) is demonstrated in a very shallow strained germanium (Ge) channel, which is located only 22 nm below the surface. The top-gate of a dopant-less field effect transistor controls the channel carrier density confined in an undoped Ge/SiGe heterostructure with reduced background contamination, sharp interfaces, and high uniformity. The high mobility leads to mean free paths ≈ 6 µm, setting new benchmarks for holes in shallow field effect transistors. The high mobility, along with a percolation density of 1.2 × 1011cm−2, light effective mass (0.09me), and high effective g-factor (up to 9.2) highlight the potential of undoped Ge/SiGe as a low-disorder material platform for hybrid quantum technologies.

Original languageEnglish
Article number1807613
Number of pages8
JournalAdvanced Functional Materials
Issue number14
Publication statusPublished - 2019


  • germanium
  • mobility
  • quantum devices
  • quantum well


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