GREEN LUMINESCENCE FROM COPPER-DOPED ZINC-SULFIDE QUANTUM PARTICLES

Free-standing powder of zinc sulphide quantum particles has been synth esized using a chemical route. X-ray diffraction analysis shows that t he diameter of the particles is similar to 21+/-2 Angstrom which is sm aller than the Bohr exciton diameter for zinc sulphide. UV absorption shows an excitonic peak centered at similar to 300 nm corresponding to an energy gap of 4.1+/-0.1 eV. These particles show a luminescence ba nd at similar to 424 nm. The quantum particles could be doped with cop per during synthesis without altering the UV absorption or x-ray diffr action pattern. However, doping shifted the luminescence to 480 nm, gr een wavelength in the visible region. (C) 1995 American Institute of P hysics.