Auger Recombination in Quantum Dot Materials @ University of Minnesota
January 12, 2010 :: Highlight from IRG4
: Ryan Gresback, Uwe Kortshagen- University of Minnesota
Auger recombination is a mechanism in which the excitation energy stored in an electron-hole pair is transferred to another charge carrier. It is an important mechanism that can limit the performance of semiconductor lasers and solar cells. Ryan Gresback, a graduate student in Professor Kortshagen's group, was involved in a study with the group of Dr. Victor Klimov at Los Alamos National Lab, comparing Auger recombination rates of direct and indirect band gap semiconductor nanometer-sized crystals, so-called quantum dots. In bulk semiconductors, Auger recombination rates differ by 4-5 orders of magnitude for direct and indirect band gap materials. In this study, the researchers reported the first experimental observation of a striking convergence of Auger recombination rates in quantum dots of both direct (InAs, PbSe, CdSe) and indirect band gap (Ge) semiconductors, which is in contrast to the dramatic difference in the Auger decay rates in the respective bulk solids. This study supports that at the nanometer-size scale the difference in the photo-physics of direct and indirect band gap materials ceases to exist.
