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

Research output: Contribution to journalArticleScientificpeer-review

23 Citations (Scopus)
107 Downloads (Pure)


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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