Fig. (13) The weak-field Hall-geometry factor of devices with three contacts and a single mirror symmetry versus its 2 DoF of the layout. In (a) the 2 DoF are λ_ed, λ_d in (b) the 2 DoF are the resistances of the ERC normalized to the sheet resistance R_d/R_sh, R_e/R_sh and in (c) the 2 DoF are the resistances between two contacts normalized to the sheet resistance R_{C1 → C2}/R_sh, R_{C1 → C3}/R_sh. The black solid curves denote devices with electrical symmetry R_d = R_e (i.e.λ_d = λ_e = 3λ_ed and R_{C1 → C2} = R_{C1 → C3}). R_e 2R_d means the parallel connection of R_e and 2R_d.