Inserting an "atomic trap" for directional dopant migration in core/multi-shell quantum dots

Area of Science:

• Solid-state chemistry and materials science
• Nanotechnology and quantum dot synthesis
• Computational materials science

Background:

• Ion diffusion in crystalline lattices is vital for solid-state technologies.
• Controlling ion diffusion in nanoscale lattices presents significant challenges.
• Dopant migration in quantum dots (QDs) impacts their properties but is difficult to manage.

Purpose of the Study:

• To investigate a method for controlling dopant migration in core/multi-shell quantum dots (QDs).
• To utilize an alloyed interface layer as an "atomic trap" to facilitate directional dopant migration.
• To understand the influence of doping site and lattice environment on dopant mobility.

Main Methods:

• Fabrication of core/multi-shell quantum dots with an inserted CdZnS alloyed interface layer.
• Experimental observation and analysis of manganese (Mn(ii)) dopant migration.
• Density functional theory (DFT) calculations to determine energy barriers for dopant hopping.

Main Results:

• The CdZnS interface layer effectively acted as an "atomic trap," facilitating controlled Mn(ii) dopant migration.
• Dopant migration was significantly influenced by the host lattice site; larger Cd(ii) sites promoted migration, while smaller Zn(ii) sites inhibited it.
• DFT calculations confirmed higher energy barriers for Mn(ii) hopping from smaller Zn substitutional sites compared to larger Cd sites.

Conclusions:

• Controlled dopant migration via "atomic trapping" is achievable in QDs using an alloyed interface layer.
• The initial doping site and local lattice distortion critically influence dopant mobility and stability.
• This approach offers a novel strategy for tuning the properties of doped nanomaterials.