###Atomic-scale quantum-electronic devices in germanium
Project ID: 2228bd1024 (You will need this ID for your application)
Research Theme: Quantum Technologies
UCL Lead department: London Centre for Nanotechnology (LCN)
Lead Supervisor: Steven Schofield
Project Summary:
Why this research is important: Germanium is an exceptionally promising material for the fabrication of nano- and atomic-scale quantum technological devices. Compared to silicon, germanium has a higher electron mobility, stronger spin-orbit coupling, larger Bohr radius, larger Stark effect, is relatively insensitive to exchange coupling oscillations, and donors in germanium have long coherence times.
Atomic-scale devices have been fabricated using phosphorus in silicon, including the single-atom transistor [Nature Nanotechnology 7, 242 (2012)] and a two quantum-bit device [Nature 571, 371 (2019)]. However, there is a fundamental problem with the use of phosphine in silicon that strongly limits scale-up to larger numbers of deterministically positioned donors (qubits).
Recently, in our group, we discovered a method for incorporating arsenic donors into germanium, involving the exposure of atomically-clean germanium (001) surfaces to arsine (AsH3) gas [arXiv:2203.08769 (under review at Angewandte Chemie)]. This method provides a solution to the scale-up problem and provides a path toward fabricating quantum technology devices in germanium.
Who you will be working with: This work fits within a wider scope of research in the fabrication and measurement of atomic-scale semiconductor devices at the LCN and will involve collaboration with Neil Curson (LCN/EEE), Taylor Stock (EEE), Andrew Fisher (LCN/P&A), and Mark Buitelaar (LCN/P&A).
What you will be doing: You will develop the capability to spatially control the incorporation of arsenic into germanium with atomic-scale precision using the atomic manipulation capabilities of the scanning tunnelling microscope (STM). You will assess the limits of spatial positioning accuracy and fabricate a range of devices. Devices will be characterised using cryogenic temperature STM (LCN) and synchrotron-based photoelectron spectroscopy methods (e.g, at Diamond or the Swiss Light Source).
Who we are looking for: A student with a strong background in solid-state physics and interest in the experimental fabrication of atomic-scale electronic devices in germanium.