Structural and optical studies of indium gallium arsenide/gallium arsenide quantum dot molecules for terahertz applications

A quantum dot molecule-based Terahertz emitter allows the engineering of intraband transitions and leads to reduced absorption losses. A background of the growth mechanisms for the dots, the background and application of quantum dot molecules (QDMs), optical and structural characterization methods employed in quantum dot research, and the theoretical advantages of III-V quantum dots are discussed in this thesis.; A study of the structural and optical properties of In0.3Ga 0.7As/GaAs QDMs formed by two layers of self-assembled, vertically stacked quantum dots is presented. Structural parameters, as determined from transmission electron microscopy studies were used to calculate the strain. The calculated strain field was subsequently used to determine the electronic bandstructure. The theoretically calculated electronic bandstructures were found to be in good agreement with those experimentally measured by using the time integrated photoluminescence technique. In order to understand the QDM properties excitation and temperature dependent photoluminescence studies were conducted.