Fig. 2
From: Gate-controlled quantum dots and superconductivity in planar germanium
Fabrication and operation of a gate-defined quantum dot. a False-coloured SEM image of the quantum dot device. The quantum dot is defined under the top gate TG (dotted circle) and its occupancy can be controlled by the central plunger gate P. BS and BD correspond to source and drain barriers, respectively; FS and FD are finger gates for additional control. Scale bar is 100 nm. b Schematic of the device gate layers, showing the top gate and the ohmic contacts achieved by in-diffusion of Al. Scale bar is 50 nm. c Transport measurements showing Coulomb oscillations as a function of the top gate with VP = 0 mV and as a function of the plunger gate with VTG = −2120 mV (inset). d, e Influence of the barrier gates BS with VBD = 500 mV (d) and BD with VBS = 500 mV (e) on the observed conductivity. The coupling of the two individual gates to the quantum dot is nearly identical, emphasising the excellent homogeneity reached in this system
