Tuning the Through-Space Charge Transfer Emission in Triarylborane and Triarylamine Functionalized Dipeptide Organogels

We report herein a new class of either carbazolyl or BMes2 (Mes = mesityl) group functionalized Boc-Lys(Z)-Phe-OMe (Z = carbobenzyloxy) dipeptides—Boc-Lys(Z)-Phe-C5-carbazolyl (N2) and Boc-Lys(Z)-Phe-C6-BMes2 (B2). Both of the compounds are...

Локализация носителей заряда в квантовых ямах InGaN/GaN, ограниченная объемным зарядом

The mechanism of carrier tunneling through the potential walls of InGaN/GaN quantum well in the p-n structures is studied by means of the deep center tunneling spectroscopy. A number of humps on the current and photocurrent tunneling spectra, as well as on the forward bias dependences of the intensity and the peak energy of photoluminescence band from the quantum well are detected. These findings allow us to propose a model of carrier localization in the quantum well that permit to relate the tunneling transparency of the potential walls of the QW to the space-charge of deep-level centers in the quantum well barriers and its changes under optical excitation and forward biasing of p-n structure.

Low-Temperature Annealing of CdZnTeSe under Bias

We performed a gradual low-temperature annealing up to 360 K on a CdZnTeSe radiation detector equipped with gold and indium electrodes under bias at both polarities. We observed significant changes in the detector’s resistance and space-charge accumulation. This could potentially lead to the control and improvement of the electronic properties of the detector because the changes are accompanied with the reduction in the bulk dark current and surface leakage current. In this article, we present the results of a detailed study of the internal electric field and conductivity changes in CdZnTeSe detector for various annealing steps under bias taking into account different polarities during annealing and subsequent characterization. We observed that low-temperature annealing results in an increase in the barrier height at the contacts that, in general, reduces the dark current and decreases the positive space charge present in the sample compared to the pre-annealed condition.

CHARGE DISTRIBUTION IN THE AlO - SiO SYSTEM EXPOSED TO IONIZING RADIATION

Полупроводниковые МДП (металл - диэлектрик - полупроводник) структуры являются ключевыми элементами современной электронной техники, в том числе устройств работающих в условиях воздействия проникающих излучений. Одним из возможных подходов к уменьшению радиационных эффектов в МДП структурах является использование диэлектриков, которые уменьшают генерацию и накопление избыточного пространственного заряда в объеме диэлектрика. В работе исследована система диэлектриков AlO - SiO. Исследование показывает пригодность использования МДП структур, на основе системы диэлектриков, для формирования приборов с высокой радиационной стойкостью. Нанесение слоя AlO поверх слоя SiO улучшает рабочие характеристики МДП структур за счет повышения однородности параметров. Основной эффект влияния слоя AlO на параметры структур заключается в уменьшении механических напряжений на границе SiO-подложка. Захват ловушками электронов в AlO, компенсирует заряд захваченных дырок в AlO, и снижает паразитный ток через AlO. Metal-insulator-semiconductor (MIS) structures are key elements of modern electronic technology, including devices operating under conditions of exposure to penetrating radiation. One of the possible approaches to reducing radiation effects in MIS structures is the use of dielectrics, which reduce the generation and accumulation of excess space charge in the bulk of the dielectric. We investigated the system of dielectrics AlO - SiO. The study shows the suitability of using MIS structures based on a system of dielectrics for formation of devices with high radiation resistance. Applying a AlO layer on top of the SiO layer improves the performance of MIS structures by increasing the uniformity of parameters. The main effect of the influence of the AlO layer on the parameters of the structures is to reduce the mechanical stresses at the interface SiO -substrate. The trapping of electrons in AlO, compensates for the charge of the trapped holes in SiO, and reduces the parasitic current through AlO.

Composite Micro-Nanoarchitectonics of MMT-SiO2: Space Charge Characteristics under Tensile State

Low density polyethylene (LDPE) is a good insulating material which is widely used in cable materials due to its excellent insulation and processability. However, in the DC high voltage environment, pure polyethylene materials still face many problems, the most serious of which is space charge accumulation. The cable will inevitably be subjected to tensile stress during production, installation and operation. Therefore, it is of great significance to study the effect of stretching on the microstructure and space charge characteristics for polymers and their composites. In this paper, MMT/LDPE micro-composites, SiO2/LDPE nano-composites and MMT-SiO2/LDPE micro-nano-composites were prepared by melt blending. Mechanical stretching was carried out on pure LDPE materials and the above three kinds of composite materials. Each material was stretched according to four stretching ratios, which are 0%, 5%, 10% and 20%. The crystal morphology was observed by polarizing microscope (PLM), the crystallization perfection was tested by differential scanning calorimetry (DSC), and the space charge distribution inside each sample was measured by pulsed electro-acoustic (PEA) method. At the same time, the average charge density and apparent charge mobility for samples during depolarization were calculated and analyzed. The experimental results show that when the pure low density polyethylene sample is not stretched, its crystal structure is loose. Tensile stress can make the loose molecular chains align in LDPE and improve its crystalline structure, which is helpful to restrain the accumulation of space charge inside the sample. For MMT/LDPE, SiO2/LDPE and MMT-SiO2/LDPE composites, their internal crystal structure is compact. Stretching will destroy their original crystal structure at first, and then disorder molecular chains inside the three composite materials. With the increase of stretching ratio, the molecular chains begin to orient along the direction of force, the crystallization tends to be perfect gradually, and the space charge accumulation in samples also decreases. From the calculation results of apparent charge mobility for each sample, with the increase of stretching ratio, the trap depth and trap density inside samples firstly increased and then decreased.