A complete fabrication route for atomic-scale, donor-based devices in single-crystal germanium

Area of Science:

• Semiconductor nanoelectronics
• Germanium (Ge) based devices
• Atomic-scale fabrication

Background:

• Germanium (Ge) shows promise for ultrascaled classical transistors and quantum devices.
• Traditional silicon CMOS fabrication processes face challenges with Ge, particularly rapid dopant diffusion, hindering electron confinement.
• The field of Ge nanoelectronics is nascent, requiring novel fabrication techniques.

Purpose of the Study:

• To establish a complete fabrication route for atomic-scale, donor-based devices in single-crystal Ge.
• To overcome the hurdle of electron confinement in Ge due to fast dopant diffusion.
• To demonstrate a method for bridging atomic-scale patterned structures with external circuitry.

Main Methods:

• Utilized scanning tunneling microscope (STM) lithography for atomic-scale patterning.
• Employed high-quality crystal growth techniques for single-crystal Ge.
• Developed an innovative lithographic procedure using direct laser patterning of the semiconductor surface.

Main Results:

• Successfully fabricated atomic-scale, donor-based devices in single-crystal Ge.
• Demonstrated electron confinement in a 5 nm wide phosphorus-doped nanowire within Ge.
• Observed Ohmic behavior at cryogenic temperatures.
• Measured a low planar resistivity of 8.3 kΩ/□.

Conclusions:

• The developed fabrication route enables the creation of atomic-scale devices in Ge.
• This method addresses the critical challenge of electron confinement in Ge nanoelectronics.
• The findings pave the way for advanced Ge-based transistors and quantum devices.