Nanocrystal Quantum Dots
نویسنده
چکیده
214 Semiconductor lasers are ubiquitous in modern society and play a key role in technologies ranging from CD players to optical telecommunications. Current-generation lasers have high power output and low lasing thresholds, are stable over a wide range of temperatures, and are cheap and easy to produce. Still, there is room for improvement. We are developing a new type of laser based on ultrasmall bits of semiconductor material called quantum dots (QDs). Consisting of only a few hundred to a few hundred thousand atoms, QDs bridge the gap between the solid state and single atoms, and hence these specks of matter exhibit a mix of solid-state and atomic properties. In our work, we concentrate on nanoparticles that are synthesized by colloidal chemistry, and therefore, they are often called colloidal or nanocrystal QDs (NQDs). Interestingly, the emission wavelength (that is, the emission color) of QDs depends on the dot size, and in the case of semiconductor nanocrystals, color can be controlled precisely through simple chemistry. We are therefore developing an altogether new type of color-selectable lasing medium. Although this paper focuses on our NQD laser work, quantum dots are “bigger” than lasers. Because of their small dimensions and size-controlled electronic spectra, NQDs can be viewed as tunable artificial atoms with (b) CdSe Quantum Dot (QD)
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