Figure 1
From: Critical aspects of substrate nanopatterning for the ordered growth of GaN nanocolumns
Influence of surface roughness on the selective columnar growth. Top row: typical example of (a) an ideal smooth mask obtained by EBL, (b) masks with increased roughness in the area around the holes obtained by EBL, and (c) a FIB mask with bumps around the holes. Insets: cross-section AFM analysis of the nanoholes. Bottom row: growth results using the respective masks in the upper row. (d) With an ideal smooth mask, perfect ordered growth is achieved; in the case of local higher roughness around the holes, typical donut-shaped growth is observed from the (e) top view and (f) side view SEM images.