Synthesis and optical characterization of infra-red emitting mercury sulfide (HgS) quantum dots

Abstract

A simple synthetic route to ∼4 nm diameter mercury sulfide (HgS) QDs existing in the cubic metastable (β-HgS) crystal phase is first demonstrated. Essential experimental evidence to support atomistic tight binding models of negative band gap HgS quantum dots (QDs) is presented. Optical characterization of the β-HgS QDs shows photoluminescence (PL) peaking at ∼1.1 eV, a band gap of ∼1.21 eV, and a ∼90 meV Stokes shift with the PL originating from two distinct processes. In the absence of any previous comprehensive experimental evidence these observations are discussed in light of various models of HgS electronic properties and found to be in strong agreement with atomistic tight binding theory. These materials offer potential for application as low-energy photodetectors and as excitonic insulators.