We noticed that Figures 1, 2, and 4(a) in the original publication were of poor quality due to formatting issues. This erratum provides corrected versions of those figures. The original results and discussions were not affected. RHEED images in the inset to the Fig. 1 are now fully visible. Figure 2 shows now properly fitted frames for the AFM image with the correctly placed height scales. Figure 4(a) shows now a correctly presented block diagram for the effective measurement circuit.