Figure 1. Characterization of flexible TIs thin film (Bi 2 Te 3 on PET substrate) ( a ) FESEM image of the FTTF (flexible TIs thin film), inset I is the EDS data of the selected portion as shown in the figure. Inset II and III (right side corner) show the deposited FTTF with variation in thickness. ( b ) UV absorption spectra of FTTFs. The black and red curves represent UV absorption data for 10 nm and 25 thick films respectively. Inset represents the estimation of the bandgap. ( c ) Raman characterization of the film. ( d ) Schematics of the photodetector device and insets show the flexibility of the deposited