Low-temperature SEM studies of beam-induced voltage contrast in YBCO thin films

Beam‐induced voltage contrast has been demonstrated in a superconducting thin film of YBa2Cu3O7‐x (YBCO) grown on MgO. Copper‐rich inclusions in the material contribute to spatially varying resistive behaviour but do not account for all the observed details. A new method of scanning in which the beam was moved away from the sample between each data acquisition point was found to increase the resolution by limiting thermalisation, to allow imaging of resistive features as small as 0.5 μm. Direct comparisons of beam‐induced contrast and micro‐structure at 9000 times magnification were possible using simultaneous image acquisition via a purpose‐built image store. Mounting a preamplifier within the scanning electron microscope chamber, to give a variable overall gain of 1000–100,000, was also found to significantly improve the signal‐to‐noise ratio.