Relaxation Polarization in Hydrogenated GaSe Layered Crystals

The dielectric properties of hydrogenated Gallium Selenide crystals are investigated. It is shown that the frequency dependences of ε' and ε'' permittivity components in HxGaSe have relaxation character and are described by the Cole-Cole distribution. Keywords: gallium selenide, permittivity, polarization.</span

Хімія. Методичні рекомендації та завдання до самостійної роботи з дисципліни для студентів усіх спеціальностей (частина 1)

The methodical instructions contain individual tasks in the course of chemistry, which are compiled on the topics of the theoretical course.Методичні рекомендації містять індивідуальні завдання відповідно до тем теоретичного курсу хімії

Fabrication and Characterization of Photosensitive n-CdO/p-InSe Heterojunctions

Photosensitive n-CdO/p-InSe heterojunctions were developed and studied for the first time. The heterojunctions were fabricated by dc reactive magnetron sputtering of CdO thin films onto the freshly cleaved p-InSe single-crystal substrates (0 0 1). Surface morphology of the obtained films was studied by means of atomic force microscopy. From the X-ray diffraction result it is shown that the CdO film is polycrystalline with cubic structure. The mechanisms of current transport through the space-charge region under forward and back biases were established by investigation of temperature dependences of the I-V characteristics. The main photoelectric parameters and the photosensitivity spectra were measured at room temperature

Annealing effect on I-V characteristic of n-ZnO-p-InSe heterojunction

The article is devoted to studying of influence of vacuum low-temperature annealing on the electrical and photoelectric characteristics of n-ZnO-p-InSe heterostructure. Indium monoselenide (InSe) is a semiconductor of the A3B6 group of layered compounds. The basic unit consists of two planes of metal atoms sandwiched between two planes of chalcogen atoms (Se-In-In-Se). The absence of dangling bonds on InSe cleaved surface makes it possible to use this semiconductor as a substrate for fabrication of heterostructures based on semiconductor materials with different symmetries and lattice spacings. Zinc oxide (ZnO) is the most suitable material for window materials and solar cells buffer layers application due to its marvelous transparency in the range of visible region. InSe single crystals were grown by the Bridgman technique from a nonstoichiometric melt and characterized by a pronounced layered structure along the whole length of a sample. ZnO thin oxide film was formed on freshly cleaved van der Waals surface of InSe layered crystal. n-ZnO-p-InSe heterostructure was prepared by the method of high-frequency magnetron sputtering. Sensitivity spectral areas were identified by MDR-3 monochromator with a resolution of 2.6 nm/mm. The current-voltage characteristics of the n-ZnO-p-InSe heterostructures showed a clearly pronounced diode character. In the forward bias of the initial samples, the diode factor had the value 3.7 at room temperature. It is shown that vacuum low-temperature annealing reduces shunt currents of the heterojunction, which is reflected in the decrease in the values of n from 3.7 to 2.7

Основні поняття й закони хімії. Методичні рекомендації та завдання.

The theoretical themes of "Basic concepts and laws of chemistry", are examples of solving common tasks, in order to consolidate the material there are presented self-study tasks for solving.Розглянуто теоретичні положення теми «Основні поняття й закони хімії», наведено приклади розв’язку типових задач з метою закріплення матеріалу, подано задачі для самостійного розв’язування

Capacitors on the basis of intercalate GaSe<KNO3>

The compound GaSe is obtained by the technique of intercalation of a GaSe single crystal in a melt of the ferroelectric salt KNO3. The x-ray analysis of its crystal structure has been carried out and dielectric frequency characteristics of samples has been measured. It is estab-lished, that accumulation of electric charges occurs in the examined examples in frequency area 100—1000 Hz. A sample of filter capacitor has been created on the basis of the re-ceived compounds

Heterostructures manufactured by annealing of InSe monocrystals in sulfur vapor

InS/InSe heterostructures were created by a long-term (during 120 h) thermal processing of InSe monocrystals in sulfur vapor. Investigations of electrical and photoelectric properties of structures manufactured by this method showed essential advantage of the anysotype heterostructure n-InS/p-InSe in comparison with its isotype analog. A comparison of the spectral properties of n-InS/p-InSe heterostructures obtained at different times of annealing were performed. The quantities of interband transitions and parameters of the unit lattice cell were determined defined for the InS film

Photocapacitor based on nanocomposite n-InSe<RbNO3>

The n-InSe nanocomposite material was obtained by the method of intercalation of the InSe layered single crystal from a melt of RbNO3 ferroelectric salt, which can be used for the production of a high-specific capacitance photoconductor. X-ray analysis of the structure, AFM-imaging of the surface and measurement of dielectric frequency characteristics of the samples were carried out. It was found that the intercalated InSe samples keeps the type of monocrystalline structure, and the spectrum of X-ray diffraction pattern indicates the implantation of the intercalant in the van der Waals gaps of layered InSe single crystal with an increase in the parameters of the crystal lattice. AFM images of the surface of nanocomposite material layers show the RbNO3 islands in the form of nanosized rings. The islands' height does not exceed the width of van der Waals gap for InSe, which is ≈ 0,35 nm, and the average outside diameter of the rings is ≈ 50 nm. The ensemble of nanorings is characterized by a high surface density in (0001) plane of the crystal layers (109—1010 cm–2). Thus, the physical phenomena of self-organization of nanostructures with ionic conductivity on the surfaces of layers with a molecular type of bond are used in the making of nanocomposite material for the proposed photoconductor. This allows us to obtain arrays of nanosized 2D inclusions with ionic conductivity and with given geometrical sizes, morphology and spatial distribution in a matrix of a layered crystal. The developed photoconductor has a high specific electrical capacity, a high coefficient of overlapping of the capacity (≈ 109) in the light, has the ability to accumulate electric charge, it can be used as a low-voltage semiconductor device in optoelectronic memory systems, in photoelectric sensors, in light energy converter and in the storage of electric energy

Electrical Properties of Cd Doped InSe Crystals

The measurements of electrical conductivity along (alternating electric field) and across (direct electric field)the crystallographic C axis of Cd‐doped indium selenide single crystals are carried out. The parameters of thehopping conductivity of InSe &lt;Cd&gt; are calculated.Keywords: layered crystal, indium selenide, conductivity.</p

Low-Impedance Investigations of Hydrogenated GaSe Layered Crystals

The structure, electrical and dielectric properties of hydrogenated gallium selenide crystals were investigated. It was shown that AC-conduction mechanism along the crystallographic axis C in the 103–105 Hz have hopping character. The parameters of the band theory of hopping conduction were calculated. The frequency dependence of ε' and ε'' components of permittivity in HxGaSe were obtained. Keywords: gallium selenide, hopping conduction, permittivity.</span