Fig. 4From: Fabrication of 20.19% Efficient Single-Crystalline Silicon Solar Cell with Inverted Pyramid MicrostructureSEM images of inverted pyramid (cross sections in insert) processing for different time. SEM images: a nanoporous silicon and b–f inverted pyramid surface-section and cross section texturing at 60 °C in aqueous NaOH solution for 1, 3, 5, 7, and 9 min, respectivelyBack to article page