Fig. 1

Resistivity versus temperature (\(\:\rho\:\left(\varTheta\:\right)\)) characteristic for pristine devices of width (a) w = 20 μm (green diamonds) fabricated on high-resistivity silicon, of width (b) w = 20 μm (orange triangles) fabricated on sapphire, and of width (c) w = 100 μm (violet squares) fabricated on high-resistivity silicon. For each device, measurements collected both cooling down and warming up are presented. The arrows indicate the temperature direction and the numbers the temporal sequence (in order from darker to lighter). For the w = 100 μm device on Hi-Res Si and for the w = 20 μm device on AlOx, two consecutive sets are present.