Soft Processing for the Introduction of Metal Dopants to Metal Sulfide Semiconductor Thin Films and Nanoparticles

UoM administered thesis: Phd

  • Authors:
  • Emmanuel Onche

Abstract

This thesis describes a cheap, easily scalable and solvent-free method for doping semiconductors of group II-VI nanoparticles using melt reactions. Dithioimidodiphosphinate metal complexes of Pb, Cd and Zn were used as source of host metal sulfides while complexes of Mn, Zn and Fe were used as a source of metal dopants. Two doping regimes were obtained based on the appropriate range of mole fractions (0.02, 0.04, 0.06, 0.08, 0.10 and 0.12) of dopants which is wide enough to shed light on previously hidden regimes. Based on this, the choice of dopants in either the interstitial or substitutional positions is possible in the dithioimidodiphosphinate metal sulfide systems. The positions of the metal dopants (Mn2+, Zn2+ and Fe2+) on the host semiconductors (PbS, CdS and ZnS ) affect the microstructures and therefore, the optical properties of the doped semiconductors. The physical changes introduced to the unit cells of the host metal sulfides by the presence of metal dopants were studied using XRD, SEM, EDX, PL and Raman spectroscopy. The Debye-Scherrer and Williamson-Hall plots were used to study the contributions of crystal sizes and lattice strain on p-XRD peak broadenings. The p-XRD analysis showed that there was no phase change in any of the dithioimidodiphosphinate metal sulfide systems that were doped. We also show that Cu, Zn and Sn dithioimidodiphosphinate single source precursors can be used in tandem to produce the solar absorber material Cu2ZnSnS4 (CZTS), for potential use in type III cells.

Details

Original languageEnglish
Awarding Institution
Supervisors/Advisors
Award date31 Dec 2019