Fig. 2
From: High-Efficiency Silicon Inverted Pyramid-Based Passivated Emitter and Rear Cells
Morphology of the prepared Si inverted pyramid structures (Si IPs-strus). a SEM image of porous silicon obtained by MACE. b SEM image of nanoholes by the following modifications in the HF/HNO3 mixed solutions. c–e SEM images of inverted pyramids (cross section in inset) by the etching in aqueous NaOH solution at 60 °C for 30, 60, and 90 s, respectively. f Compared photos for different surface structures corresponding to a–e