Fractal pattern formation in thermal grooving at grain boundaries in Ag films on Si(111) surfaces

► Thermal grooving in Ag films grown on Si(111) surfaces has been investigated. ► At appropriate temperatures short annealing shows partly depleted grain boundaries. ► Depleted grain boundaries reveal a fractal pattern with a fractal dimension of 1.60. ► Long annealing produces percolated Ag-depleted regions with isolated Ag grains. ► A thorough analysis shows that current theories are unable to explain the results.