Photosensing and Characterizing of the Pristine and In-, Sn-Doped Bi(2)Se(3) Nanoplatelets Fabricated by Thermal V–S Process

Pristine, and In-, Sn-, and (In, Sn)-doped Bi(2)Se(3) nanoplatelets synthesized on Al(2)O(3)(100) substrate by a vapor–solid mechanism in thermal CVD process via at 600 °C under 2 × 10(−2) Torr. XRD and HRTEM reveal that In or Sn dopants had no effect on the crystal structure of the synthesized rhombohedral-Bi(2)Se(3). FPA–FTIR reveals that the optical bandgap of doped Bi(2)Se(3) was 26.3%, 34.1%, and 43.7% lower than pristine Bi(2)Se(3). XRD, FESEM–EDS, Raman spectroscopy, and XPS confirm defects ([Formula: see text]), ([Formula: see text]), ([Formula: see text]), ([Formula: see text]), and ([Formula: see text]). Photocurrent that was generated in (In,Sn)-doped Bi(2)Se(3) under UV(8 W) and red (5 W) light revealed stable photocurrents of 5.20 × 10(−10) and 0.35 × 10(−10) A and high I(photo)/I(dark) ratios of 30.7 and 52.2. The rise and fall times of the photocurrent under UV light were 4.1 × 10(−2) and 6.6 × 10(−2) s. Under UV light, (In,Sn)-dopedBi(2)Se(3) had 15.3% longer photocurrent decay time and 22.6% shorter rise time than pristine Bi(2)Se(3), indicating that (In,Sn)-doped Bi(2)Se(3) exhibited good surface conduction and greater photosensitivity. These results suggest that In, Sn, or both dopants enhance photodetection of pristine Bi(2)Se(3) under UV and red light. The findings also suggest that type of defect is a more important factor than optical bandgap in determining photo-detection sensitivity. (In,Sn)-doped Bi(2)Se(3) has greater potential than undoped Bi(2)Se(3) for use in UV and red-light photodetectors.