Photosensing and Characterizing of the Pristine and In-, Sn-Doped BiSe Nanoplatelets Fabricated by Thermal V-S Process.

Pristine, and In-, Sn-, and (In, Sn)-doped BiSe nanoplatelets synthesized on AlO(100) substrate by a vapor-solid mechanism in thermal CVD process via at 600 °C under 2 × 10 Torr. XRD and HRTEM reveal that In or Sn dopants had no effect on the crystal structure of the synthesized rhombohedral-BiSe. FPA-FTIR reveals that the optical bandgap of doped BiSe was 26.3%, 34.1%, and 43.7% lower than pristine BiSe. XRD, FESEM-EDS, Raman spectroscopy, and XPS confirm defects (In3+Bi3+), (In3+V0), (Sn4+Bi3+), (V0Bi3+), and (Sn2+Bi3+). Photocurrent that was generated in (In,Sn)-doped BiSe under UV(8 W) and red (5 W) light revealed stable photocurrents of 5.20 × 10 and 0.35 × 10 A and high I/I ratios of 30.7 and 52.2. The rise and fall times of the photocurrent under UV light were 4.1 × 10 and 6.6 × 10 s. Under UV light, (In,Sn)-dopedBiSe had 15.3% longer photocurrent decay time and 22.6% shorter rise time than pristine BiSe, indicating that (In,Sn)-doped BiSe exhibited good surface conduction and greater photosensitivity. These results suggest that In, Sn, or both dopants enhance photodetection of pristine BiSe 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 BiSe has greater potential than undoped BiSe for use in UV and red-light photodetectors.