Optoelectronic Properties and Applications of Quantum Dots

In semiconductor quantum dots (QDs) are called artificial atoms, sharing some of the optical and optoelectronic properties with atoms. This chapter focuses on the epitaxially grown QDs and presents the applications of colloidal QDs. It briefly discusses some different techniques for the epitaxial growth of semiconductor QDs of high optical quality. The elementary electronic excitation, the exciton, in semiconductor QDs is an electron–hole pair excited across the electronic bandgap within the QD as defined by the bulk energy gap and the quantization energies within the conduction and valence bands, respectively, and modified by the Coulomb interaction between electron and hole. Since quantitative absorption experiments are difficult to carry out on epitaxially grown QDs, the optical and optoelectronic properties of QDs are most conveniently studied in photoluminescence experiments where the QDs are excited via absorption in the barrier material and subsequent relaxation and capture of electrons and holes into their lowest quantized states in the QDs.