Red luminescence of spherical Cu_xZn_(1-x)S semiconductor nanoparticles using 2-mercaptoethanol as capping agent

摘要

Cu~(2+)-doped (0-2 at%) ZnS nanoparticles stabilized by 2-mercaptoethanol (2-ME) were successfully prepared using wet precipitation route in aqueous solution. The structural and optical characteristics were studied by various techniques. XRD pattern showed zinc blende cubic structure of Cu~(2+)-doped ZnS with grain size of 4±0.5 nm. Spherical shape and well distribution of particles is confirmed by TEM, SEM and STM microscopy. Copper doping were identified by elemental dispersive (EDS) spectrometry. UV-vis spectroscopy revealed strong confinement effect due to blue shift in absorption shoulder peak as compared to bulk ZnS. Red luminescence band at～657 nm on Cu~(2+) doping may be arising from recombination of electrons at sulfur vacancies (V_s) and Cu(t_2) states formed at ZnS band gap. Optimum concentration of 0.25 at% (red band) of Cu~(2+) doping was selected by the observed enhanced PL emission.