Surface and Quantum Effects in Nanosized Semiconductor

Abstract

Novel properties of nano-scale semiconductors based on the surface and quantum effects have been studied and applications identified. Spherical potential well model is used to study quantum effect whereas basic geometrical models are used for the surface effect. We have shown such effects to be the fundamental factors responsible for the novel nanosized semiconductor characteristics different from the bulk of same material. It is found that the surface area to volume ratio follows inverse power law. Thus at nanoscale, the surface to volume ratio increases significantly to enhance chemical reactivity. In addition, the increased surface area makes most nananocrystals highly soluble in liquid and dramatically lowers their melting temperature. The result strongly suggests also that the shape of the nanoparticles influences the surface area which has huge impact on their properties and performance. Our results of quantum size effect reveal that spatial confinement of charge carriers within semiconductor nanocrystals significantly modulates their properties such as size dependent absorption and emission spectra with non-zero discrete electronic transition energies as well as their blue shift band gaps. Thus by changing the size of the particle, we can literally fine-tune a material property of interest such as optical, electrical, and surface area. Specifically we found that InAs and InSb nano semiconductor optical absorption spectrum, in contrast to their bulk, can be tuned in broad range of UV to IR regions which are favorable operating wavelengths for nano photonic technology such as IR photo detectors and full spectrum solar cells applications.

Hot carrier exploitation strategies and model for efficient solar cell applications

“…The incorporation of QDs that simultaneously offer an improved optical absorption, photo-excited carrier collection and phonon bottleneck effects are presently being explored. QDs are semiconductors in nanometer dimensions providing strong quantum confinements on the carriers in 3D leading to discrete and size dependent energy spectrum in sharp contrast to the bulk matter whose electronic states are distributed in continuous bands as depicted in Figure 4, thus making QDs typical example of live quantum mechanical phenomenon [24]. The discrete energy level spectrum in QDs is a replica of atomic energy spectra which confers on them the moniker "artificial atoms" [25].…”

Synthesis of Copper Nanoparticles by Using Solenostemma argel Extract and Its Application as an Antimicrobial Agent

“…The availability of copper has made it a better choice to work with because it shares properties similar to those of other expensive noble metals, including silver and gold. The choice of copper in the present research is attributed to the factors mentioned above; copper nanoparticles are reported to have antimicrobial activity against several species of bacteria and fungi [8,[10][11][12][13].…”