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CPP: Chemische Physik und Polymerphysik

CPP 4: SYMPOSIUM Materials for Molecular Electronics

CPP 4.2: Talk

Monday, March 24, 2003, 15:00–15:30, ZEU/160

Colloidal Semiconductor Nanocrystals- Lasers from a Nano-world — •Hans Eisler, Vikram Sundar, and Moungi Bawendi — MIT, Department of Chemistry, Cambridge, MA USA

The advantages of three-dimensional quantum confinement have long motivated research towards the creation of color-selective lasers based on colloidal semiconductor nanocrystals (NCs). Recent observations of amplified spontaneous emission (ASE) from close-packed films of cadmium selenide (CdSe) nanocrystals have hastened efforts to develop appropriate NC-microcavity feedback structures, and demonstrate true laser action from these nanocrystals. This talk details our efforts in this regard. We describe a novel sol-gel NC/titania matrix, which provides a facile technique for spin-coating waveguides showing ASE. Some novel characteristics of these waveguides include their greater stability, processability and ability to fine-tune their refractive index: features we use to create more-complicated structures showing ASE simultaneously at different wavelengths. Lastly, we report on the successful creation of optically pumped lasers utilizing these NC-titania films as the gain media and distributed feedback (DFB) gratings as the optical feedback mechanism. Novel features of the resulting lasers are detailed, including the ability to tune the output color by simply changing the size of the constituent NC and the ability to operate these lasers at temperatures varying from 80 K to room temperature.