Bandgap Engineering of the II-IV, III-V and IV-VI Semiconductor Quantum Dots for Technological Applications

H. I. Ikeri, A. I. Onyia, V. C. Onuabuchi

Bandgap Engineering, Quantum Confinement, Quantum Dot, Schrodinger Equation, Spherical Potential Well, Emission and Absorption Spectrum.

Bandgap engineering in semiconductor quantum dots (QDs) has been studied for technological applications. The model obtained demonstrates that the optical bandgap can be tuned to custom-designed by varying the confinement size. This results in dramatic improvement in band-to-band excitation energy and hence a blue shift in the absorption and luminescence with decreasing QD size. This offers potential revolutionary solutions in many areas of modern science and engineering technology to overcome the fundamental limitation of conventional semiconductors that have their bandgap fixed. In addition, QDs display broad absorption band characteristics with narrow-emission spectra that are tunable due to size quantization effects, which contribute to advancement of medical imaging and multiplexing potentials such as multicolor detection with a single wavelength excitation energy. It is found that CdSe and CdS QDs posses an optical spectrum that confer on them potential active materials for efficient light emitting diode (LED) and lasers operating over the whole range of visible region. ZnS QD possesses the widest bandgap energy which plays a vital role for absorption and emission of high energy blue photons and permits devices to operate at much higher voltages and temperatures crucial for optoelectronic device applications such as Pn junctions and power transistors. In addition, the wide bandgap absorption spectra will be relevant in high optical transmittance specifically in the range of visible to infra red (IR) spectral region. GaAs, InAs and InSb QDs show promising optical bandgap energies in the visible to near infrared (NIR) spectral region which is desirable for optoelectronic devices, operating at NIR wavelengths. We found that PbS, PbSe and PbSe QDs displayed exceptional optical characteristics that are favorable for solar cells applications owing to the fact that their absorption band are fairly good match to the solar spectrum.

https://dx.doi.org/10.31873/IJEAS.8.7.01