Design of patterned sapphire substrates for GaN-based light-emitting diodes<xref ref-type="fn" rid="cpb150397fn1">*</xref>

Design of patterned sapphire substrates for GaN-based light-emitting diodes*

Wang Hai-Yan^a), Lin Zhi-Ting^a), Han Jing-Lei^a), Zhong Li-Yi^a), Li Guo-Qiang^a),^b)

SEM images of the air gaps of V-shaped-groove PSSs with different pattern periods of (a) 6 μm and (b) 18 μm; GaN nucleation distribution of V-shaped-groove PSSs in different stages: (c) low-temperature 30-nm-thick GaN nucleation; (d) annealing; (e) high-temperature 0.5-μm-thick GaN layer.^{[ 27 ]}