Summary of the technology
Doping of semiconductors by impurity atoms enabled their widespread technological application in micro and optoelectronics. However, for strongly confined colloidal semiconductor nanocrystals, doping has proven elusive. This arises both from the synthetic challenge of how to introduce single impurities and from a lack of fundamental understanding of this heavily doped limit under strong quantum confinement. We develop a method to dope semiconductor nanocrystals with metal impurities providing control of the band gap and Fermi energy. A combination of optical measurements, scanning tunneling spectroscopy and theory revealed the emergence of a confined impurity band and band-tailing. Successful control of doping and its understanding provide n- and p-doped semiconductor nanocrystals which greatly enhance the potential application of such materials in solar cells, thin-film transistors, and optoelectronic devices.
Project ID : 3-2011-179
Intentionally inserting impurity atoms into a crystal, or doping, is the basis for the widespread application of semiconductors in electronic and electro-optic components.
An additional way to tune the properties of semiconductor structures is by controlling their size and dimensionality via quantum confinement effects.
Colloidal semiconductor nanocrystals are a family of materials that have size-dependent optical and electronic properties, and lend themselves to the simple manufacture of nanocrystal-based light-emitting diodes, solar cells, and transistor devices.
However, doping has proven elusive for strongly confined colloidal semiconductor nanocrystals.
Simple, room-temperature method for doping semiconductor nanocrystals with metal impurities. Exquisite control of the electronic properties, including the band gap and Fermi energy achieved through changing the dopant type and concentration.
First demonstration of electronic doping of quantum confined semiconductor nanocrystals under heavily doped regime
Provided understanding of the effects of heavy doping in semiconductor nanocrystals
Simple doping method in solution at room temperature using metal dopant atoms developed
Project in research phase, moving towards demonstrating a device based on doped nanocrystals
The ability to closely control the synthesis of doped nanocrystals, together with a better understanding of heavily-doped colloidal Quantum Dots opens potential avenues for solar cells, thin-film transistors, and diverse electronic and optoelectronic devices.