Heavily Doped Semiconductor Nanocrystal Quantum Dots

TL;DR

This paper presents a novel method for doping semiconductor nanocrystals with metal impurities, enabling control over their electronic properties and advancing their application potential in optoelectronics.

Contribution

It introduces a new doping technique for colloidal semiconductor nanocrystals and provides fundamental insights into impurity band formation under quantum confinement.

Findings

Controlled doping of nanocrystals achieved

Emergence of impurity band and band-tailing observed

Enhanced potential for optoelectronic applications

Abstract

Doping of semiconductors by impurity atoms enabled their widespread technological application in micro and opto-electronics. For colloidal semiconductor nanocrystals, an emerging family of materials where size, composition and shape-control offer widely tunable optical and electronic properties, 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.