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The two facts: the presence of a very limited amount of impurities in a semiconductor, will substantially change the conductivity, the optical characteristics as well as other properties and the modern and advanced methods for growth of semiconductor quantum structures makes the fabrication of these quantum structures very controlled and accurate directly imply the importance of the area...
The recent development of advanced growth techniques such as molecular beam epitaxy and metal-organic vapor phase epitaxy has made it possible to fabricate ultrathin semiconductor layers, quantum structures, with an accuracy down to atomic layer thickness. This means that dimensions smaller than the de Broglie wavelength of the electrons can be achieved. We have accordingly advanced from the classical...
The possibility to incorporate impurities in the semiconductor crystal to change its optical and electrical properties is of paramount importance for the applications of semiconductors. The incorporation of an impurity to the semiconductor crystal corresponds to an effective addition of a charge carrier and a charged impurity ion to the system. The impurities will give rise to localized states in...
The electrons in a 3D bulk crystal can be described by Bloch waves, which can propagate throughout the lattice in an unrestricted way. If this freedom is limited in one direction by introducing potential barriers, a two-dimensional nanostructure, a quantum well, is formed. In this way, the properties of electronic particles in the quantum well will be modified [1–3].
In analogy with the hydrogen atom binding an extra electron to form the negatively charged H-ion, a donor in a semiconductor might bind another electron to form a negatively charged donor.
The properties of quantum well structures are strongly influenced by the presence of dopant impurities either in the well or in the barrier. As long as the impurity concentration is low, the wave functions of the impurities are spatially separated and the energy levels of the associated states are discrete. However, when the impurity concentration increases, an overlap of the impurity wave functions...
The fact that hydrogen interacts efficiently with most defects, shallow dopants as well as deep centers, with the formation of hydrogen-impurity complexes and saturation of dangling bonds as a result, has contributed to a great interest in the hydrogen passivation process. From a technological point of view, the hydrogen passivation plays an important role both at the growth and the processing phases...
The early calculations on the impurity states in quantum wells were based on the one-band effective mass approximation (EMA), which earlier has been successfully applied on the corresponding shallow impurity states in 3D bulk material. In the original theoretical work for the confined impurity states, Bastard performed calculations on the electronic structure of the impurities in quantum wells assuming...
The valence band top of bulk semiconductors with zincblende and diamond structures exhibits a fourfold degeneracy, due to the Td symmetry, which must be taken into account, when the acceptor states are calculated. Because of the more complex valence band structure, the electronic structure of an acceptor is also much more complicated than for the donor case.
The introduction of impurities, even in very small concentrations, in a semiconductor can change its optical and electrical properties entirely. This attribute of the semiconductor is utilized in the manifoldness of their applications. In this book, the progress on elucidating the physical properties of impurities confined in quantum structures are reviewed with an emphasis on the experimental aspects...
We report on an indirect optical method for the determination of glucose via the detection of hydrogen peroxide (H2O2) that is generated during the glucose oxidase (GOx) catalyzed oxidation of glucose. It is based on the finding that the ultraviolet (~374 nm) and visible (~525 nm) photoluminescence of pristine zinc oxide (ZnO) nanoparticles strongly depends on the concentration of H2O2 in water solution...
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