Mapping the Origins of Surface- and Chemistry-Dependent Doping Trends in III–V Quantum Dots with Density Functional Theory

Modifying
the optoelectronic properties of nanostructured materials
through the introduction of dopant atoms has attracted intense interest,
but the approaches employed are often trial and error, preventing
rational design. We demonstrate the power of large-scale electronic
structure calculations with density functional theory (DFT) to build
an atlas of preferred sites for a range of M­(II) and M­(III) dopants
in the representative III–V InP magic size cluster (MSC). We
quantify the thermodynamic favorability of doping, which we identify
to be both specific to the sites within the MSC (i.e., interior vs
surface) and to the nature of the dopant atom (i.e., smaller Ga­(III)
vs larger Y­(III) or Sc­(III)). For isovalent M­(III) doping (i.e., Y,
Sc, or Ga), we observe stronger sensitivity of the predicted energetics
to the ligand binding mode on the surface than to the dopant type.
For M­(II) (i.e., Zn or Cd) dopants, we show that the binding mode
of ligand removed to balance charge during the doping reaction is
critical. We observe limited cooperativity with dopants up to moderate
concentrations, indicating that rapid single-dopant estimations of
favorability from DFT can efficiently guide rational design.