The possibility of controlling the composition of lateral nanowires by the method of growth under quasi-equilibrium conditions in a quasi-closed volume from indium, phosphorus, and arsenic vapors with Au catalyst in the “vapor-liquid-solid” mechanism has been demonstrated for the first time. It has been experimentally shown that the additional presence of arsenic in the indium-phosphorus source leads to the coalescence of catalytic gold droplets at the initial stage of the growth, which determines the further morphology and growth kinetics of nanostructures. An additional formation of indium phosphide nanostructures with a composition different from that of the main nanowires was found. The results of the studies expand the possibilities of the developed method for obtaining lateral nanowires on gallium arsenide substrates.

The influence of substrate temperature on the morphology of indium tin oxide films deposited by magnetron sputtering and electron beam evaporation is demonstrated. It is found that during magnetron sputtering, the degree of film structuring increases with a rise in the substrate temperature. Based on the X-ray phase analysis of the samples, the structured films are described in terms of two phases: the first of which is an untextured sublayer with the properties corresponding to the material obtained at room temperature; the second one is textured elongated crystals with a large cell parameter, a large crystallite size, and without microstrains. The structural features and optical characteristics of studied films are compared with the structured film obtained by electron beam evaporation. The study of transmission and reflection spectra of the obtained films show that the film deposited at a temperature of 400 degrees C are characterized by the antireflection effect over a wide range of wavelengths.

The paper describes the results of optimizing rapid thermal annealing (RTA) of ohmic contacts to AlGaN:Si layers with a high aluminum content (70 mol%) and various electron concentration. The contact characteristics were measured using the transmission line method (TLM). It has been found that for highly doped Al0.7Ga0.3N:Si layers (>1018cm-3), the RTA annealing of Ti(25nm)/Al(80nm)/Ti/Au contact at a temperature 900 & DEG;C for 60 s makes it possible to obtain the minimum contact resistance of 8 & omega;xmm and specific contact resistivity of 9x10-4 & OHM;& BULL;cm2 with high uniformity over the surface of a 2-inch substrate. For lightly doped Al0.7Ga0.3N:Si layers (<1017 cm-3), almost the same contact characteristics can be achieved at a higher RTA temperature of about 1000C and an increase in the thickness of the Al contact layer to 250 nm.

we present the results of fabrication of flip-chip LEDs with removed substrate from AlInGaN heterostructures grown on SiC/Si substrates synthesized by vacancy-matching atom substitution. It is shown that SiC/Si substrates are optimal from the viewpoint of matching lattice parameters, thermal conductivity, and optical characteristics of the material at a significantly lower cost. Therewith, the procedure of cutting wafers into individual chips and removal of the opaque silicon part of the substrate becomes easier, and the transparent SiC part of the substrate remaining on the chip surface creates a relief that facilitates light output.

In this paper, the water wettability of nanostructured ITO films, including those with Al2O3 protective layers, was studied. Nanostructured ITO films were deposited by mag-netron sputtering and electron beam evaporation on the preheated surface of a glass substrate, after which they were additionally annealed in a nitrogen atmosphere for 10 min. Some samples were covered with an aluminium oxide layer with various thicknesses. The Al2O3 protective coating was fabricated by atomic layer deposition. To estimate the wettability, we measured the contact angles of water drops on the horizontal surface of the films. The results show that, depending on the deposition method and thickness, structured ITO films can be characterized both by hydrophilic and by hydrophobic properties. In the case of covering of the nanostruc-tured ITO film deposited by the electron beam evaporation with a protective coating of alumin-ium oxide, the hydrophobic properties of structured ITO films can be significantly improved and a superhydrophobic coating can be obtained.

We present the results of fabrication of flip-chip LED chips with removed substrate from AlInGaN heterostructures grown on SiC/Si substrates synthesized by vacancy-matching atom substitution. It is shown that SiC/Si substrates are optimal from the viewpoint of coordinated lattice parameters, thermal conductivity, and optical characteristics of the material at a significantly lower cost. In addition, the procedure of cutting wafers into individual chips, removal of the opaque silicon part of the substrate, and the transparent SiC part of the substrate remaining on the chip surface creates a relief that facilitates light output.

A technique and technology for manufacturing both LED chips and packaged LEDs from AlInGaN/GaN heterostructures grown on novel SiC/Si substrates synthesized by the method of matched substitution of atoms is described. We have studied the current-voltage characteristics, electroluminescence spectra, and dependence of output power and external quantum efficiency on the current. It is shown that the presence of pores in the SiC/Si substrate, which are naturally formed during its growth, leads to a significant increase in the quantum efficiency of LEDs compared with the quantum efficiency of LEDs fabricated on silicon without a SiC sublayer.

In this work, the antireflective nanostractured ITO/Al2O3 coatings that have a gradient of the effective refractive index in the direction perpendicular to the substrate plane have been studied. The coatings were obtained by the atomic layer deposition (ALD) of aluminum oxide on the structured ITO films. The transmission electron microscopy showed that the deposited nanosized aluminum oxide layer was of good quality and uniformly covered the ITO whiskers. As shown in experiments, the thickness of the resulting Al2O3 layer is affected by the thickness and, hence, by the degree of surface roughness of the initial ITO film. The resulting thicknesses can be several times lower than that planned in the experiment, based both on the calculations of the parameters of the ALD process and on the direct measurements of the aluminum oxide deposition rate for unstructured ITO films. A possible reason that affects the growth rate of A1O3 layers in nanostructured ITO films is a strong increase in the surface area of the ITO film during its structuring. So, the transmission and scanning microscopy data for a 700 nm-thick structured ITO film have shown that its surface area is more than 20 times greater than that of a smooth film.

In this work, research is carried out to analyze the possibility of fabricating nanostructured antireflection coatings based on ZnO. The dependence of structural features of the film on the substrate heating temperature during the deposition of aluminum-doped zinc oxide (AZO) is studied. It is shown that it is impossible to obtain the required structural properties of the film by changing a single parameter: the substrate temperature during deposition of the material in the range of 20–600°C. For this purpose, an approach is suggested, which consists in the preliminary deposition of a nanometer-thick Sn layer with subsequent substrate heating to the temperature of deposition of the main material layer. Optimization of the coating-deposition conditions leads to the fabrication of a medium consisting of many whiskers with transverse dimensions of tens of nanometers and a length of hundreds of nanometers, which are oriented mainly perpendicular to the substrate. It is shown that the gradient nature of a change in the material density, and, hence, in the effective refractive index in the direction perpendicular to the substrate plane, provides antireflection properties of the coating over a wide range of wavelengths as well as in different directions of light propagation.

The atomic-layer-deposition technique is used for the deposition of supplementary Al2O3 nanolayers onto nanostructured optically transparent and conductive indium–tin oxide (ITO) coatings produced by electron-beam evaporation. ITO coatings consisting of mainly vertically oriented whiskers and possessing an effective refractive index that steadily decreases in the direction orthogonal to the substrate plane are used. The influence of the thickness of the deposited Al2O3 layer on the optical characteristics of the samples is studied. It is shown that the atomic layer deposition technique provides a means for uniformly coating whiskers of thick nanostructured ITO films, in which the upper whiskers shade the lower ones, with protective shells. This will make it possible to fabricate antireflective conductive coatings that are more resistant to external impacts and which possess the required parameters. With the protective Al2O3 layer deposited, the gradient behavior of the refractive index inherent in the initial ITO film is retained.

A new method for growth of Au-catalyzed lateral Ga(In)AsP nanostructures in a quasi-closed volume from a vapor source under semi-equilibrium conditions has been studied. Varied time-temperature conditions and nucleation modes were examined. It was found that lateral nanostructures elongated in the [1 (1) over bar0] direction are formed on a (100) GaAs substrate at about 500 degrees C. Raising the growth temperature is accompanied by a significant change of the morphology of the nanostructures. The modified surface has a random textured structure with predominant pyramidal faceting. Changes in the alloy composition of the nanostructures were studied.

In this work, the antireflective nanostructured ITO/Al2O3 coatings that have a gradient of the effective refractive index in the direction perpendicular to the substrate plane have been studied. The coatings were obtained by the atomic layer deposition (ALD) of aluminum oxide on the structured ITO films. The transmission electron microscopy showed that the deposited nanosized aluminum oxide layer was of good quality and uniformly covered the ITO whiskers. As shown in experiments, the thickness of the resulting Al2O3 layer is affected by the thickness and, hence, by the degree of surface roughness of the initial ITO film. The resulting thicknesses can be several times lower than that planned in the experiment, based both on the calculations of the parameters of the ALD process and on the direct measurements of the aluminum oxide deposition rate for unstructured ITO films. A possible reason that affects the growth rate of Al2O3 layers in nanostructured ITO films is a strong increase in the surface area of the ITO film during its structuring. So, the transmission and scanning microscopy data for a 700-nm-thick structured ITO film have shown that its surface area is more than 20 times greater than that of a smooth film.

Впервые продемонстрирована возможность управления составом латеральных нитевидных наноструктур при использовании метода роста в квазиравновесных условиях в квазизамкнутом объеме из паров индия, фосфора и мышьяка с использованием Au-катализатора по механизму "пар-жидкость-твердое тело". Эксп-риментально показано, что дополнительное присутствие мышьяка в источнике индий-фосфор приводит к коалесценции каталитических капель золота на начальном этапе роста, что определяет дальнейшую морфологию и кинетику роста наноструктур. Обнаружено дополнительное образование наноструктур фосфида индия с составом, отличным от состава основных нитевидных наноструктур. Результаты проведенных исследований значительно расширяют возможности разработанного нами метода получения латеральных нитевидных наноструктур на подложках арсенида галлия. Ключевые слова: планарные нитевидные нанокристаллы InGaAsP, механизм роста "пар--жидкость--твердое тело", спектроскопия комбинационного рассеяния, фотолюминесценция.

На полученные методом электронно-лучевого испарения наноструктурированные оптически прозрачные и проводящие покрытия из оксида индия + олова методом атомно-слоевого осаждения наносились дополнительные слои Al2O3 нанометровой толщины. Использовались покрытия из оксида индия + олова, содержащие нитевидные кристаллы преимущественно вертикальной ориентации и обладающие эффективным показателем преломления, монотонно убывающим в направлении, перпендикулярном плоскости подложки. Изучалось влияние толщины наносимого слоя Al2O3 на оптические характеристики получаемых образцов. Показано, что применение метода атомно-слоевого осаждения позволяет равномерно покрывать защитными оболочками нитевидные кристаллы наноструктурированных пленок из оксида индия + олова большой толщины, в которых верхние нити затеняют нижележащие, что позволит получать более стойкие к воздействию внешней среды просветляющие проводящие покрытия с требуемыми параметрами. При нанесении защитного слоя Al2O3 сохраняется градиентный характер показателя преломления, присущий исходной пленке ITO. Ключевые слова: метод атомно-слоевого осаждения, наноструктурированные пленки ITO.

In this work, research was carried out to analyze the possibility to fabricate nanostructured antireflection coatings based on ZnO. The dependence of structural features of the film on the substrate heating temperature during deposition of an aluminum-doped zinc oxide (AZO) has been studied. It is shown that it is impossible to obtain the required structural properties of the film by changing one parameter, the substrate temperature during deposition of the material, in the range of 20 – 600 °C. For this purpose, an approach has been suggested, which consists in preliminary deposition of a nanometer-thick Sn layer with subsequent substrate heating up to the temperature of deposition of the main material layer. The optimization of coating deposition conditions led to the fabrication of a medium consisting of many whiskers with transverse dimensions of tens of nanometers and a length of hundreds of nanometers, which are oriented mainly perpendicular to the substrate. It is shown that the gradient nature of a change in the material density, and, hence, in the effective refractive index in the direction perpendicular to the substrate plane, provides antireflection properties of the coating over a wide range of wavelengths as well as in different directions of light propagation.

The technique and technology for fabricating both LED chips and packaged LEDs based on InGaN/GaN heterostructures grown on novel SiC/Si substrates synthesized by the method of matched atomic substitution have been described. The current-voltage characteristics, luminescence spectra, and the current dependences of output power and external quantum efficiency have been studied. It is shown that the presence of pores naturally formed in the SiC/Si substrate during its growth leads to a substantial increase in the quantum efficiency of LEDs in comparison with that of LEDs fabricated on silicon without a SiC sublayer.

The kind of profile produced during the reactive ion etching of AlGaInN light-emitting-diode (LED) heterostructures on the surface that became free after removal of the growth substrate is studied in relation to the composition of the gas mixture used in the etching process. It is shown that using a mixture composed of Cl2 and Ar, taken in a 3:2 ratio in terms of flow rates, leads to the thinnest profile, whereas a 2 : 1 gas mixture of BCl3 and Ar provides the largest structural elements. To study the effect of the kind of profile on the quantum efficiency (QE), flip-chip LEDs are fabricated on a silicon substrate. The LEDs are etched in different modes after the growth substrate is removed. Etching in the Cl2:BCl3:Ar mixture with a flow ratio of 6:10:11, which leads to intermediate sizes of the etching profile elements, is optimal for obtaining maximum light extraction from a LED chip at a wavelength of 460 nm. The variation of the kind of profile with the gas-mixture composition suggests that the profile parameters can be tuned to the wavelength used. An analysis of how the QE of LED chips depends on the etching duration in the three-component mixture under consideration results in that the optimum etching duration is estimated to be ~30 min. The results of the study can also be of use in the search for conditions minimizing the reflection of incident light by a chip, e.g., for photodetectors.

Abstract The kind of profile produced during the reactive ion etching of AlGaInN light-emitting-diode (LED) heterostructures on the surface that became free after removal of the growth substrate is studied in relation to the composition of the gas mixture used in the etching process. It is shown that using a mixture composed of Cl_2 and Ar, taken in a 3:2 ratio in terms of flow rates, leads to the thinnest profile, whereas a 2 : 1 gas mixture of BCl_3 and Ar provides the largest structural elements. To study the effect of the kind of profile on the quantum efficiency (QE), flip-chip LEDs are fabricated on a silicon substrate. The LEDs are etched in different modes after the growth substrate is removed. Etching in the Cl_2:BCl_3:Ar mixture with a flow ratio of 6:10:11, which leads to intermediate sizes of the etching profile elements, is optimal for obtaining maximum light extraction from a LED chip at a wavelength of 460 nm. The variation of the kind of profile with the gas-mixture composition suggests that the profile parameters can be tuned to the wavelength used. An analysis of how the QE of LED chips depends on the etching duration in the three-component mixture under consideration results in that the optimum etching duration is estimated to be ~30 min. The results of the study can also be of use in the search for conditions minimizing the reflection of incident light by a chip, e.g., for photodetectors.

A relief on the surface of GaN previously released from the growth substrate is formed by a combined method in which reactive ion etching is used in combination with liquid etching (in KOH or hydrochloric-acid solutions). The dependence of obtained relief on the sequence of operations used is studied. It is shown that etching in a KOH solution followed by reactive ion etching provides the appearance of truncated hollow cones on the surface. In experiments, the ability of a hydrochloric-acid solution for etching exclusively GaN relief elements formed by reactive ion etching of the surface is also found. As a result, reactive ion etching of the sample followed by immersion into hydrochloric acid forms objects of cylindrical shape on its surface transforming at the base into conical or strongly distorted pyramidal structures. The appearance of this relief can be explained by the predominance of the chemical component in reactive ion etching with increasing distance from the sample surface. Further optimization of the relief parameters obtained as a result of combined etching is possible by varying the modes of operation under use.

We have shown the possibility of Ga(In)AsP on GaAs (100) nanowire growth in a quasi-closed volume from the vapour phase witn the use of Sn catalyst. We have investigated the dynamics of nanowire formation depending on the growth time at constant V/III ratio given by the process temperature. It is shown that growth of free-standing nanowires is realized through the vapor-liquid-solid mechanism. Based on the Raman scattering data sequential growth of two phases have been shown. Phosphorous concentration in free-stamding nanowires was estimated to be high.