Optical and Surface Structural Properties of Mn2+ Doped ZnSe Nanoparticles

T.J. Norman, D. Magana, T. Wilson, C. Burns, D. Cao, F. Bridges and J.Z. Zhang
University of California Santa Cruz, US

Keywords: nanoparticles, ZnSe, Mn2+, XAFS

Abstract:
Four Mn2+ doped ZnSe nanoparticles, one with low Mn2+ concentration (A), one with an intermediate Mn2+ concentration (B), one with a high Mn2+ concentration (C), and one with no Mn2+, were synthesized. The sample with no Mn2+ had a sharp ZnSe bandedge emission peak. The samples with Mn2+ had a significant decrease in bandedge emission. Sample A had no Mn2+ 4T1à 6A1 emission, but showed some ZnSe bandedge emission and trap state emission. Sample B had Mn2+ 4T1à 6A1 emission and a further reduction in ZnSe bandedge emission and trap state emission. Sample C showed an increase in the Mn2+ 4T1à 6A1 emission, a dramatic increase in trap state emission. XAFS and ESR data were taken on the samples. The XAFS data indicated there was a reduction in the Zn and Mn first neighbor Se coordination from the bulk value but a lack of a reduction in the Se first neighbor coordination. This suggests that the core of the nanoparticles resembles that of bulk ZnSe, and the surface of the particle has a higher concentration of metal atoms. We propose that the surface Mn2+ possessed an octahedral geometry, and the overall low emission is primarily due to the surface Mn2+.

Nanotech 2004 Conference Technical Program Abstract