Synthesis and characterization of indium doped cadmium sulfide nanoribbons

This paper reports the synthesis and optical characterization of indium doped cadmium sulfide (CdS) nanoribbons (NRs) by the metal-catalyzed vapour-liquid-solid growth method. The NRs had a hexagonal wurtzite structure, lengths of up to 100 νm, widths of 0.6-15 νm and thicknesses of 30-60 nm. Indium doping into the CdS lattice was identified and characterized by low-temperature photoluminescence and photoconductivity measurements. Temperature-dependent photoluminescence (PL) measurements showed that the PL spectra of the In-doped CdS NRs have three emission peaks at 9 K, which can be attributed to band edge emission (2.510 eV) and shallow donor levels (2.398 eV and 2.366 eV) due to doping, respectively. Photoconductive characteristics including spectral response and light intensity response of the doped CdS NR were also investigated. The dark current in the doped CdS NRs was found to be one order higher in magnitude than that of the intrinsic, which can be attributed to effective incorporation of the indium dopant in the CdS crystal lattice and, subsequently, the reduction in the recombination barrier in the nanostructures. The current jumped from 1.8 × 10^-9 to 2.1 × 10^-5 A upon white light illumination with a power density of 2 mW cm^-2. The presented results show promising application of these materials in the field of optoelectronics as photo detectors. © 2009 IOP Publishing Ltd.