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Synthesis and Characterization of Quantum Dots
Haiguang Zhao and Dongling Ma
2.1 Introduction
Semiconductor quantum dots (QDs) are uorescent nanocrystals (NCs) normally smaller
than 20 nm in diameter [1]. Typically, they are composed of an inorganic core, made up of a
few hundred to a few thousand atoms, surrounded by an organic outer layer of surfactant
molecules (ligands). Bulk semiconductors are characterized by a composition-dependent
bandgap (Figure 2.1a), which is the minimum energy required to excite an electron from
the valence band into the conduction band. With the absorption of a photon of energy
greater than the bandgap energy