HgS nanoparticles: Structure and optical properties

Nanocrystalline HgS thin films were synthesized by using an electrochemical route under galvanostatic conditions. Quantum size effects have resulted in the change of the semi-metallic behavior of bulk β-HgS (Eg=-0.5 eV) to semiconducting behavior with an absorption onset around 1.4 eV as confirmed from optical absorption studies. Glancing angle X-ray diffraction analysis confirms the presence of β-HgS (zinc-blend structure) with prominent crystallographic planes of (200), (220) and (311) in the deposit. This is consistent with results obtained from transmission electron diffraction studies. The Raman scattering measurements identified a broad 1LO confined phonon mode at 247 cm-1 which suggests that the crystalline sizes are small.