This project is co-funded by the Electronic and Photonic Materials (EPM) and Condensed Matter Physics (CMP) Programs in the Division of Materials Research (DMR).
This project is on synthesis, spectroscopy and dynamic studies of colloidal quantum dots and represents a comprehensive effort to evaluate the photophysics of colloidal dots in the mid-infrared spectral range from 3 to 10 micrometers. The research uses quantum confinement to create mid-infrared electronic transitions. The materials are the semimetal HgTe and the wide band gap semiconductors Cd(Te, Se, S). HgTe becomes a tunable mid-infrared gap semiconductor at small sizes while the Cd(Te, Se, S) colloidal dots have strong intraband transitions in this mid-infrared spectral range. The effects of confinement on energy relaxation, thermal properties, and low- and high-excitation levels are investigated by using picosecond mid-infrared time-resolved laser spectroscopy. Ligands on the colloidal dots introduce coupling of the infrared electronic excitations to molecular vibrations. Processing is developed to eliminate or reduce the effect of organic ligands, which will allow slower phonon relaxation and Auger processes, facilitating photodetection and lasing.
The project addresses basic research issues in a topical area of materials research, with potential technological impacts. Success of the research will expand our fundamental understanding of the infrared properties of colloidal quantum dots in a spectral range from 3 to 10 micrometers. Potential applications of these quantum dots include infrared photodetector and lasers. Infrared detection is useful for thermal imaging and molecular detection. Infrared lasers are useful for spectral analysis of atmospheric contaminants and telecommunications. In this project, graduate and undergraduate students are trained in an interdisciplinary environment that combines materials science, physics, and chemistry.