A Complete Fabrication Route for Atomic-Scale, Donor-Based Devices in Single-Crystal Germanium

Abstract

Despite the rapidly growing interest in Ge for ultrascaled classical transistors and innovative quantum devices, the field of Ge nanoelectronics is still in its infancy. One major hurdle has been electron confinement since fast dopant diffusion occurs when traditional Si CMOS fabrication processes are applied to Ge. We demonstrate a complete fabrication route for atomic-scale, donor-based devices in single-crystal Ge using a combination of scanning tunneling microscope lithography and high-quality crystal growth. The cornerstone of this fabrication process is an innovative lithographic procedure based on direct laser patterning of the semiconductor surface, allowing the gap between atomic-scale STM-patterned structures and the outside world to be bridged. Using this fabrication process, we show electron confinement in a 5 nm wide phosphorus-doped nanowire in single-crystal Ge. At cryogenic temperatures, Ohmic behavior is observed and a low planar resistivity of 8.3 kΩ/□ is measured.

Large Stark tuning of donor electron spin qubits in germanium

“…As the transistor size approaches the atomic limit [1], research has turned from miniaturizing transistors towards replacing silicon with higher performance materials like germanium [2][3][4][5]. In parallel, the field of quantum information processing has been innovating the way computers work by taking advantage of quantum effects.…”

Magnetic anisotropy in epitaxial Mn5Ge3films

“…Germanium, thanks to its small band gap and its high mobility, is believed to lead to a new generation of devices having high-speed data processing, high-density integration, and low power consumption. 2 In addition, its long spin coherence time is of great advantage for innovative spintronic devices. Recently the injection of a spin polarized current into Ge through a tunnel junction [3][4][5] has been successfully demonstrated.…”

Electronic structure of phosphorus and arsenicδ-doped germanium

“…6 Further, multiple δ-layers can be vertically stacked in the Ge crystal, preserving their individuality from a structural and electrical point of view, [7][8][9] and opening the possibility of three-dimensional epitaxial circuits comprising vertically stacked 2DEGs and atomicscale Ge:P devices. Arsenic δ-layers in germanium have not yet been produced by these lithography techniques, but there is no in-principle reason against their fabrication.…”