Fig. 4From: RETRACTED ARTICLE: Flexible Field Emitter for X-ray Generation by Implanting CNTs into Nickel FoilSEM images of the CNT/PI film etched for different times a 60, b 120, c 240, and d 480 s. SEM images of the fabricated emitter etched for different times e 60, f 120, g 240, and h 480 sBack to article page