Arsine on germanium: a new route to donor-based quantum devices.*

Efforts to construct atomic-scale donor-based quantum devices have largely focussed on positioning phosphorus donors in silicon using phosphine (PH3) as the molecular precursor.  However, recently germanium has been the focus of much attention for the creation of semiconductor quantum devices due to advantages over silicon including higher electron mobility, stronger spin-orbit coupling, larger Bohr radius, and stronger Stark effect. In this talk we introduce arsine (AsH3) on the germanium (001) surface for the creation of atomic-scale donor-based quantum devices.  We present atomic-resolution scanning tunnelling microscopy (STM) measurements combined with density functional theory (DFT) calculations.  We discuss our results in the context of atomic-scale device fabrication using STM-based hydrogen resist lithography and emphasise the unique advantages of this system compared to phosphine on silicon.