Fig. 1. (Color online) Schematic illustration of the topics of this review, including the fabrication conditions, spectroscopy, and applications in Sn-doped CdS micro-nano structures.

Fig. 2. (Color online) Images of Sn-doped CdS samples with different nanostructures. (a) SEM image of microcones, with an inset showing the optical image of the superlattice structure^[31]. (b) SEM image of nanowires. (c) SEM image of the core-shell structure^[32]. (d) Optical image of superlattice nanowires. (e) SEM image of the comb-like nanostructure^[33]. (f) Optical image of the nanobelt structure, with an inset showing the SEM image^[34].

Fig. 3. (Color online) (a) Schematic diagram of the growth process of core-shell structured nanowires. (b) Spatial distribution and local composition of O at different stages during the growth of CdS^[39].

Fig. 4. (a) and (b) are the micro Raman scattering spectra of single Sn-doped CdS nanowire with high and low CdS/SnO₂ ratios, respectively^[45].

Fig. 5. (Color online) (a)−(d) PL spectra of CdS nanowires with increasing Sn doping concentration^[45].

Fig. 6. (Color online) Optical waveguide (a) and interconnect structure (b) of a single CdS nanowire 580 μm in length, illustrated with corresponding bright-field optical images, and (c) local far-field PL spectra of CdS nanowire with uncurved structure detected at excitation points a and emission points b^[35].

Fig. 7. (Color online) (a) The relationship between near-band emission intensity and transmission distance at different excitation power densities. (b) The relationship between emission intensity and propagation distance of deep-level defects under different excitation power densities^[49].

Fig. 8. (Color online) (a) Low temperature (7 K) chemical spectra show three luminescence regions. (b) Photoluminescence spectra of Sn-doped CdS nanowire at 4 K. (c) Temperature-dependent μ-PL spectra of Sn-doped CdS nanowires. (d) Band structure of Sn-doped CdS nanowires and some exciton-non-exciton transitions^[9].

Fig. 9. (Color online) (a) Images of Sn-doped CdS nanowires under dark-field microscopy at different temperatures. (b) Temperature-dependent PL spectra of a single Sn-doped CdS nanowire ranging from 100 to 300 K. The two black vertical dashed lines indicate the positions of the near-band-edge emission peak and the maximum WGM at 300 K. (c) Schematic diagram of the luminescence mechanism of Sn-doped nanowires at 80 K. (d) Temperature (T) dependence of the intensity I of the near-band-edge emission (black curve) and the maximum WGM (red curve). (e) Temperature (T) dependence of the peak positions P of the near-band-edge emission and the maximum WGM^[52].

Fig. 10. (Color online) Far-field PL images of excited samples at different reaction times: (a) 20 min; (b) 30 min. Insets in (a) and (b) are the corresponding optical images. (c) Schematic diagram of the emission process in 1D superlattice nanowires with λ_exc = 488 nm. (d) PL spectra of periodic CdS/CdS : SnS₂ superlattice nanowires^[37].

Fig. 11. (Color online) (a)−(d) Dark-field PL images of CdS_1−xSe_x/Sn : CdS_1−xSe_x superlattice nanowires with x = 0, 0.1, 0.2, 0.4. Insets show the corresponding bright-field optical images. (e) Normalized PL spectra measured from (a)−(d)^[38].

Fig. 12. (Color online) (a) CdS nanowires and (c) CdS/CdS : SnS₂ superlattice nanowires, with insets showing the corresponding optical images. (b) and (d) show the PL spectra of CdS nanowires and CdS/CdS : SnS₂ superlattice nanowires, respectively^[55].

Fig. 13. (Color online) (a) PL spectra of a single Sn-doped CdS micrometer under different excitation wavelengths of laser. (b) PL spectra of Sn-doped CdS microcone with increasing excitation power. (c) PL spectra of a single Sn-doped CdS microcone with different cross-sectional radii^[31].

Fig. 14. (Color online) (a) ARPL spectrum of the micrometer cone sample when perpendicular to the incident slit of the monochromator. (b) ARPL spectrum of the micrometer cone sample when parallel to the incident slit of the monochromator. (c) PL spectra of the micrometer cone with different cross-sectional radii^[56].

Fig. 15. (Color online) (a) Radius-dependent circularly polarized PL spectra of Sn-doped CdS micrometer cones. (b) The relationship between the degree of polarization and the cross-sectional radius. (c) The relationship between the energy change in the PL spectra and the cross-sectional radius of Sn-doped CdS micrometer cones^[57].

Fig. 16. (Color online) (a) Lateral irradiation of the laser at the junction of the trunk and branch. (b) Irradiation of the laser at the central part of the branch. (c) Vertical irradiation of the laser at the position indicated by the white ellipse^[40].

Fig. 17. (Color online) (a) Room-temperature Raman spectra of different parts (junction/trunk/branch) of the CdS comb-like structure. (b) Raman spectra over a temperature range of 78−300 K. (c) Room-temperature photoluminescence spectra of different parts. (d) PL spectra at different temperatures^[33].

Fig. 18. (Color online) (a)−(c) Show the actual photoluminescence images at 2, 6, and 35 mW, respectively. (d) Variation of the intensity of green and red emissions with laser power. (e) Photoluminescence image of pure CdS comb-like nanostructures^[61].

Fig. 19. (Color online) Simulation analysis of luminescence modes in Sn-doped CdS porous structures with different wall thicknesses. (a)−(c) Schematic illustrations of radial optical propagation in hexagonal Sn-doped CdS porous structures with three different wall thicknesses, where the red arrows indicate the three existing mode propagation mechanisms. (d) Variation of Q with rhole and optical wavelength. (e)−(l) Electric field distributions of the eight high-Q modes corresponding to (d)^[32].

Fig. 20. (Color online) Schematic diagram of a photodetector based on CdS/CdS : SnS₂ superlattice nanowires^[55].

Fig. 21. (Color online) (a) Schematic diagram of the energy band structure and carrier transfer in the hybrid P3HT-CdS/CdS : SnS₂ superlattice nanowire structure. (b) Schematic diagram of the flexible hybrid film photodetector on paper substrate. (c) Actual image of the hybrid photodetector on paper substrate^[68].

Fig. 22. (Color online) (a) Schematic diagram of a four-quadrant photodetector. (b) Schematic diagram of the working principle of the designed photodetector^[71].

Fig. 23. (Color online) Schematic diagram of photodetector designed by Liu based on Sn-doped CdS nanowires^[49].

Fig. 24. (Color online) (a) Schematic diagram of the design of a low-threshold single-mode laser. (b) Schematic illustration of the optical path between the CdS nanoribbons and the DBR. (c) SEM image of the physical device based on this design. (d) Laser spectra of CdS nanoribbons with different thicknesses embedded in the DBR microcavity^[73].

Fig. 25. (Color online) (a) Actual photograph of nanoribbons under laser excitation, with a scale bar of 20 μm. (b) PL spectra detected at different positions marked in (a)^[34].

Fig. 26. (Color online) Automatic alignment of disordered nanowires into an array. (a) Disordered CdS nanowires. (b) Alignment process of CdS nanowires. (c) Aligned array of nanowires^[74].

Fig. 27. (Color online) (a) Spectrum at 300 K. (b) Physical images at 300 K. (c) Contours of corresponding intensity distributions at the ends of four different branches. (d) Barcode diagram at 300 K. (e)−(h) Images corresponding to room temperature conditions at 78 K^[75].

Fig. 28. (Color online) (a) and (b) True color photoluminescence images of Sn-doped CdS comb nanostructures at different excitation powers. (c) and (d) Corresponding photogenic spectrum. (e) Coding strategy based on SN-doped CdS comb nanostructures^[75].