Electrical properties of semiconductor structures with Si nanoclusters in SiO 2 grown by high temperature annealing technology of SiO X layer, X<2

Abstract. The theoretical and experimental investigations of electrical properties of the SiO 2 /Si-ncs/SiO 2 /Si structures grown by high temperature annealing SiO X , X<2, have been carried out. The influence of Si cluster growth conditions on frequency dependences of V C characteristics, static and dynamic conductance of investigated structures has been clearly observed. As a result of theoretical modeling, V C dependences have been calculated. The experimentally obtained negative constituent of differential capacitance has been qualitatively described. It has been experimentally found that the SiO 2 /Si-ncs/SiO 2 /Si structures with the tunnel dielectric layer revealed the effect of memorizing

ДОСЛІДЖЕННЯ ВОЛЬТ-ФАРАДНИХ ЗАЛЕЖНОСТЕЙ, ЩО МАЮТЬ НЕГАТИВНУ ДИФЕРЕНЦІАЛЬНУ ЄМНІСТЬ, ДІОДІВ ШОТТКІ З GAAS/INAS КВАНТОВИМИ ТОЧКАМИ

Сapacitance-voltage investigations were made on Schottki diodes with embedded GaAs/InAs quantum dots and quantum wells. An effect of the negative differential capacitance(NDC) was clear observed. Numerical modeling of the C-V dependences was carried out with temperature and concentration of QDs as parameters. Energy structure of the investigated samples was examined by deep level transient spectroscopy(DLTS). It was shown that the proposed model is in good agreement with experiment and describe well the NDC effect. Вольт-фарадные исследования проводились на диодах Шоттки с GaAs/InAs квантовыми точками и квантовыми ямами. На экспериментальных зависимостях наблюдался эффект негативной дифференциальной емкости(НДЕ). Энергетическая картина структур исследовалась с помощью релаксационной спектроскопии глубоких уровней. Было проведено численное моделирование вольт-фарадных зависимостей, которое описывает эффект НДЕ и хорошо совпадает с экспериментальными результатами.  Вольт-фарадні дослідження проводилися на діодах Шотткі з GaAs/InAs квантовими точками та квантовими ямами. Експериментально спостерігався ефект негативної диференціальної ємності(НДЄ). Енергетична картина структур досліджувалася за допомогою релаксаційної спектроскопії глибоких рівнів. Було проведено чисельне моделювання вольт-фарадних залежностей, де параметрами були температура та концентрація квантових точок, що описує ефект НДЄ та добре співпадає з експериментальними результатами.

Site-Selective Oxidative Coupling Reactions for the Attachment of Enzymes to Glass Surfaces through DNA-Directed Immobilization

Enzymes are able to maintain remarkably high selectivity toward their substrates while still retaining high catalytic rates. By immobilizing enzymes onto surfaces we can heterogenize these biological catalysts, making it practical to study, use, and combine them in an easily controlled system. In this work, we developed a platform that allows for the simple and oriented immobilization of proteins through DNA-directed immobilization. First, we modified a glass surface with single-stranded DNA. We then site-selectively attached the complementary DNA strand to the N-terminus of a protein. Both DNA modifications were carried out using an oxidative coupling strategy, and the DNA strands served as easily tunable and reversible chemical handles to hybridize the protein–DNA conjugates onto the surface. We have used the aldolase enzyme as a model protein to conduct our studies. We characterized each step of the protein immobilization process using fluorescent reporters as well as atomic force microscopy. We also conducted activity assays on the surfaces with DNA-linked aldolase to validate that, despite being modified with DNA and undergoing subsequent immobilization, the enzyme was still able to retain its catalytic activity and the surfaces were reusable in subsequent cycles

Nanoimaging of Electronic Heterogeneity in Bi2Se3 and Sb2Te3 Nanocrystals

Topological insulators (TIs) are quantum materials with topologically protected surface states surrounding an insulating bulk. However, defect-induced bulk conduction often dominates transport properties in most TI materials, obscuring the Dirac surface states. In order to realize intrinsic topological insulating properties, it is thus of great significance to identify the spatial distribution of defects, understand their formation mechanism, and finally control or eliminate their influence. Here, the electronic heterogeneity in polyol-synthesized Bi2Se3 and chemical vapor deposition-grown Sb2Te3 nanocrystals is systematically investigated by multimodal atomic-to-mesoscale resolution imaging. In particular, by combining the Drude response sensitivity of infrared scattering-type scanning near-field optical microscopy with the work-function specificity of mirror electron microscopy, characteristic mesoscopic patterns are identified, which are related to carrier concentration modulation originating from the formation of defects during the crystal growth process. This correlative imaging and modeling approach thus provides the desired guidance for optimization of growth parameters, crucial for preparing TI nanomaterials to display their intrinsic exotic Dirac properties

Nanoimaging of Electronic Heterogeneity in Bi2Se3 and Sb2Te3 Nanocrystals

Topological insulators (TIs) are quantum materials with topologically protected surface states surrounding an insulating bulk. However, defect-induced bulk conduction often dominates transport properties in most TI materials, obscuring the Dirac surface states. In order to realize intrinsic topological insulating properties, it is thus of great significance to identify the spatial distribution of defects, understand their formation mechanism, and finally control or eliminate their influence. Here, the electronic heterogeneity in polyol-synthesized Bi2Se3 and chemical vapor deposition-grown Sb2Te3 nanocrystals is systematically investigated by multimodal atomic-to-mesoscale resolution imaging. In particular, by combining the Drude response sensitivity of infrared scattering-type scanning near-field optical microscopy with the work-function specificity of mirror electron microscopy, characteristic mesoscopic patterns are identified, which are related to carrier concentration modulation originating from the formation of defects during the crystal growth process. This correlative imaging and modeling approach thus provides the desired guidance for optimization of growth parameters, crucial for preparing TI nanomaterials to display their intrinsic exotic Dirac properties