THEORETICAL STUDY OF THE QUANTUM CONFINEMENT EFFECTS ON QUANTUM DOTS USING PARTICLE IN A BOX MODEL

Using particle in a box model, we have studied the quantum confinement effects on quantum dots (QDs). A mathematical equation for the confinement energy and energy gap for the quantum dot crystal was obtained and used to calculate such energies specifically for CdSe, ZnS and GaAs quantum dots. The box size was adjusted to fit the real life dot crystals that are geometrically spherical in shape rather than square and the dot particles assumed their effective masses in the periodic lattice. Results showed that discrete electronic states arose at conduction and valence bands. Therefore optical spectra of QDs showed a blue shift in the transition energy. Also, energy gap became size dependent and decreased with increasing size (radius). Thus, energy gap could be fine tuned by changing the size of QDs, which played a fundamental role in optical and electronic properties of QDs. In addition, our results indicate that confinement energy was inversely proportional to the square of QDs size. Our simple model accurately predicts QD energy gap at any radius. Among the QDs considered, CdSe quantum dot possessed distinctive optical properties that could be utilized for photonics applications owing to its size-dependent luminescence colours which spanned nearly the visible and near infra red spectra.