Nanocrystals of Narrow-Gap Semiconductors:
Strong Quantum Confinement and Infrared Light Sources

I will introduce the basic properties of semiconductor quantum dots, and then focus on the properties of lead-salt (PbS, PbSe, PbTe) nanocrystals. These structures allow us to investigate the limit of strong quantum confinement of charge carriers. They are also technologically relevant, because they are among the few material systems that can produce strong size-quantized optical transitions at wavelengths between one and two microns.