Topic
Potential well
About: Potential well is a research topic. Over the lifetime, 1430 publications have been published within this topic receiving 30812 citations.
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TL;DR: The results show that the sizes and size distribution of silicon quantum dots can be tuned by changing the annealing atmosphere and the atom ratio of silicon and carbon in the matrix.
Abstract: Silicon quantum dots embedded in an amorphous matrix of silicon carbide were realized by a magnetron co-sputtering process and post-annealing. X-ray photoelectron spectroscopy, glancing x-ray diffraction, Raman spectroscopy and high-resolution transmission electron microscopy were used to characterize the chemical composition and the microstructural properties. The results show that the sizes and size distribution of silicon quantum dots can be tuned by changing the annealing atmosphere and the atom ratio of silicon and carbon in the matrix. A physicochemical mechanism is proposed to demonstrate this formation process. Photoluminescence measurements indicate a multi-band configuration due to the quantum confinement effect of silicon quantum dots with different sizes. The PL spectra are further widened as a result of the existence of amorphous silicon quantum dots. This multi-band configuration would be extremely advantageous in improving the photoelectric conversion efficiency of photovoltaic solar cells.
32 citations
TL;DR: In this article, the relationship between the size and the emission was investigated through spectroscopic analyses to reveal the appearance of the quantum confinement effect in germanium nanocrystals (Ge NCs).
Abstract: Highly efficient ‘deep-green’ luminescent germanium nanocrystals (Ge NCs) have been synthesized by a one-step laser ablation process. The NCs are thoroughly characterized by TEM, Raman and optical spectroscopic techniques. The relationship between the size and the emission is investigated through spectroscopic analyses to reveal the appearance of the quantum confinement effect. Due to the strong quantum confinement of photogenerated carriers in diamond cubic Ge NCs and well-controlled size distribution, both a full width half maxima (FWHM) of the photoluminescence (PL) (about 55 nm) and a 17% absolute PL quantum yield (QY) of the Ge NCs in thin film form are drastically improved.
32 citations
TL;DR: In this paper, the ground state and the excited states wave functions as well as the corresponding eigenvalues of a spherical quantum dot were obtained in the presence of a confining potential which is a combination of linear, Coulomb and quadratic terms.
32 citations
TL;DR: A successful demonstration of electric-field control of ferromagnetism in the Mn(0.05)Ge( 0.95) quantum dots up to 300 K is reported, showing that, by using quantum structure, high-quality material can be obtained and effective hole mediation due to quantum confinement effect can be achieved.
Abstract: Room-temperature control of ferromagnetism by electric fields in magnetic semiconductors has been actively pursued as one of important approaches to realize practical spintronic and nonvolatile logic devices. While Mn-doped III-V semiconductors were considered as potential candidates for achieving this controllability, the search for an ideal material with high Curie temperature (T(c) > 300 K) and controllable ferromagnetism at room temperature has continued for nearly a decade. Recently, Mn(0.05)Ge(0.95) quantum dots (QDs) were demonstrated to have a T(c) above 300 K. However, the field control of ferromagnetism based on hole-mediated effect remained at low temperatures and thus prohibited spintronic devices operable at ambient environment. Here, we report a successful demonstration of electric-field control of ferromagnetism in the Mn(0.05)Ge(0.95) quantum dots up to 300 K. We show that, by using quantum structure, high-quality material can be obtained and effective hole mediation due to quantum confinement effect can be achieved. Upon the application of gate bias to a metal-oxide-semiconductor (MOS) capacitor, the ferromagnetism of the channel layer, that is, the Mn(0.05)Ge(0.95) quantum dots, was manipulated through the change of hole concentration. Our results are fundamentally and technologically important toward the realization of room-temperature spin field-effect transistors and nonvolatile spin logic devices.
32 citations
TL;DR: In this paper, the in-plane effective mass in the two-dimensional electron gas of nominally undoped AlGaN/GaN heterostructures with a different degree of quantum confinement was investigated.
Abstract: We report the results of direct measurements and a theoretical investigation of the in-plane effective mass in the two-dimensional electron gas of nominally undoped AlGaN/GaN heterostructures with a different degree of quantum confinement. It is shown that in most cases the conduction band nonparabolicity effect is overestimated and the electron wave-function penetration into the barrier layer should be taken into account. The contribution of the wave-function hybridization is determined to play the dominant role. The band edge effective mass value is deduced to be (0.2±0.01)m0.
32 citations