Germanium quantum-dot array with self-aligned electrodes for quantum electronic devices

I. Hsiang Wang, Po Yu Hong, Kang Ping Peng, Horng Chih Lin, Thomas George, Pei Wen Li*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Semiconductor-based quantum registers require scalable quantum-dots (QDs) to be accu-rately located in close proximity to and independently addressable by external electrodes. Si-based QD qubits have been realized in various lithographically-defined Si/SiGe heterostructures and val-idated only for milli-Kelvin temperature operation. QD qubits have recently been explored in germanium (Ge) materials systems that are envisaged to operate at higher temperatures, relax litho-graphic-fabrication requirements, and scale up to large quantum systems. We report the unique scalability and tunability of Ge spherical-shaped QDs that are controllably located, closely coupled between each another, and self-aligned with control electrodes, using a coordinated combination of lithographic patterning and self-assembled growth. The core experimental design is based on the thermal oxidation of poly-SiGe spacer islands located at each sidewall corner or included-angle location of Si3N4/Si-ridges with specially designed fanout structures. Multiple Ge QDs with good tunability in QD sizes and self-aligned electrodes were controllably achieved. Spherical-shaped Ge QDs are closely coupled to each other via coupling barriers of Si3N4 spacer layers/c-Si that are elec-trically tunable via self-aligned poly-Si or polycide electrodes. Our ability to place size-tunable spherical Ge QDs at any desired location, therefore, offers a large parameter space within which to design novel quantum electronic devices.

Original languageEnglish
Article number2743
Issue number10
StatePublished - Oct 2021


  • Germanium
  • Quantum dot
  • Scalability
  • Self-aligned electrode


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