Fig. 1. (Color online) Schematic top view of the patterns after processing, in which the trench width (g) is 20 μm, the stripe width (w) varies from 2 to 50 μm, the stripe length (l) is 210 μm and the height of the stripe is 0.5 μm, respectively.

Fig. 2. (Color online) Schematic diagram of the step-flow growth mode originated from sidewall on patterned substrate. The black steps denote miscut-induced steps while orange steps denote new steps from the sidewall.

Fig. 3. (Color online) 20 × 10 μm² AFM amplitude images of sample A after 1^st regrowth (a) and 2^nd regrowth (b) and sample B after 1^st regrowth (c) on the trench.

Fig. 4. 18 × 9 μm² AFM amplitude images of sample B after 2^nd regrowth (a) and 3^rd regrowth (c). (b) is 2 × 2 μm² image close to m-plane sidewall in (a), (d) is 1 × 1 μm² image close to m-plane sidewall in (c), respectively. The white dashed lines denote channels of about 1 nm deep.

Fig. 5. 20 × 10 μm² AFM amplitude images of sample C after 2^nd regrowth (a) and 3^rd regrowth (c). (b) and (d) are 2 × 2 μm² image close to m-plane sidewall in (a) and (c), respectively. The white dashed lines denote channels of about 1 nm deep.

Fig. 6. (Color online) The sketch map of relations between the adatom density n_s and terrace width d_s of steps close to the m-plane sidewall. The red line denotes the condition of high temperature or large Ⅴ/Ⅲ ratio while black line denotes the condition of low temperature or small Ⅴ/Ⅲ ratio. n_c is the critical adatom density for the occurrence of new steps from the sidewall, the terrace width is d_c at the moment.

Fig. 7. (Color online) The simulated results of morphological change on the trench at a large d_c (a) and a small d_c (b). The black, red and blue lines denote the morphology at initial stage, after 1^st regrowth and after 2^nd regrowth, respectively. The steps above the grey dashed lines are new steps from the sidewall.