Controllable Composition Ternary Group III-V Alloy Quantum Dots and Synthesis Methods
SUMMARY
- Group III-V quantum dots (QDs) are useful for applications such as photovoltaics and display technologies because of their direct band gaps and favorable electronic properties. The bandgaps of these types of semiconductors can be precisely tuned by adjusting the composition of the ternary alloys.
- As an alternative to traditional epitaxial QDs, solution processed colloidal QDs can provide a simpler, lower-cost manufacturing process for bottom-up assembly of electronic and optical devices. Precise tuning of alloy composition of colloidal QDs has however been a challenge.
- The inventors developed a method for controlling the composition of ternary alloy quantum dots using a molten inorganic salt as a solvent in cation exchange reactions. Choosing a salt combination that is stable at high temperatures and chemically inert allows the cation exchange reaction temperature to be raised high enough to overcome diffusion limitations without creating crystalline defects in the product.
- The method was used to produce In1-xGaxAs or In1-xGaxP colloidal quantum dots using a molten eutectic salt of CsBr:LiBr:KBr as a solvent for the cation exchange reaction between GaI3 and InP or InAs.
- In1-xGaxAs and In1-xGaxP colloidal quantum dots with ZnS shells showed a significantly reduced lattice mismatch, improved optical properties and increased thermostability over InP quantum dots with the same ZnS shell.
FIGURE
ADVANTAGES
ADVANTAGES
- Tunable alloy composition for desired optical properties
- Improved optical absorption properties
- Fewer crystal defects and reduced lattice mismatch
- Improved thermal stability
APPLICATIONS
- Photovoltaics
- LED display technology
- Light sensors
- In vivo biological imaging applications
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