Nanoparticles

This chapter introduces the zero-dimensional electrons in Quantum Dots (QD)s, and obtains expressions for the quantized subbands, density-of-state function, absorption, gain, and emission properties by following the simple particle-in-a box picture. Elementary ideas of growth by self-assembly are given next, mentioning the effect of size distribution in the ideal absorption spectra. The structure of QD lasers, the gain characteristics, and the competition between electron-hole and excitonic recombination are next illustrated. The difference between strong and weak confinement regimes is then pointed out. The elementary theory of excitonic processes is refined by empirical methods. A classification of nanocrystals based on growth by top-down and bottom-up methods is then given, mentioning synthesis of nanoparticles. The core-shell nanostructures are next illustrated. A brief discussion on bright and dark excitons, biexcitons, and trions then follows. Applications like QD lasers, detectors, QD infrared photodetector, solar cells, colour filters, and photochromatic glasses are mentioned.