Fig. 2

Schematic diagram of scratching process, where a–f are the corresponding process modes \( (0001)/\left[2\overline{1}\overline{1}0\right] \), \( (0001)/\left[10\overline{1}0\right] \), \( \left(01\overline{1}0\right)/\left[2\overline{1}\overline{1}0\right] \), \( \left(01\overline{1}0\right)/\left[0001\right] \), \( \left(11\overline{2}0\right)/\left[1\overline{1}00\right] \), and \( \left(11\overline{2}0\right)/\left[0001\right] \), respectively