A3B5 nanowires are usually grown via the vapor-liquid-solid mechanism. Species from the vapor are incorporated into the nanowires using a catalyst droplet. Typically, the droplet is a low-melting-point eutectic alloy of catalyst and group III metal. This growth imposes a set of limitations on the heterostructure formation and doping. Axial A3B5 heterostructure nanowires obtained via an interchange of group III metals suffer from blurring and kinking. Amphoteric dopants such as Si could act as donors and acceptors, leading to electron-to-hole ratio oscillations along the nanowire. To overcome these limits, the growth with a catalyst, which could dissolve both components of the nanowire, is studied. Tin has a eutectic with both components, As and Ga. This makes the growth of GaAs nanowires with a tin catalyst different from that with standard catalysts. Nanowire growth occurs with at least two types of catalysts, Ga-rich and Ga-poor (As-rich). This article aims to study the nanowire growth with an Sn catalyst. For the first time, the growth of GaAs nanowires using a tin catalyst by molecular beam epitaxy is shown. Tin can serve as a catalyst not only for the chemical growth of GaAs nanowires but also as a nucleation site for their growth. Both compositions of the catalyst are observed. The annealing of a thin film of tin on a Si and GaAs substrate has also been studied. At temperatures below 450 °C, small metal droplets form, while tin dissolves into the substrate at higher temperatures.

Branched III-V nanowires (NWs) are interesting both from the fundamental viewpoint and for the development of electronic and optoelectronic structures with enhanced functionality. Herein, we present a robust approach to synthesis of branched AlGaAs NWs using the Au-catalyzed molecular-beam epitaxy directly on Si(111) substrates. The second and third deposition of Au onto the substrate with NWs gives rise to the first and second generation of branches. First generation branches grow in the [1-100] direction perpendicular to the NW trunks; their coalescence yields the NW bridging. Compositional and structural analysis, performed by transmission electron microscopy and Raman spectroscopy, reveal an AlAs fraction of 0.2-0.3 and almost pure wurtzite crystal phase of both NW trunks and uncoalesced branches of the first generation. According to the microscopy measurements the wurzite phase purity is more than 95%. The method is useful for obtaining complex branched structures in wurtzite AlGaAs NWs on Si substrates, and may be translated to other material systems. These branched structures open new perspectives for next generation optoelectronic, energy harvesting and biological devices.

III-arsenide nanowires are often grown via the vapor-liquid-solid mechanism with foreign catalyst. Here we discuss the initial stage of nanowire growth with tin and lead catalyst - annealing of thin film. The influence of temperature and time of annealing was discussed.

The effect of cooling conditions in the plasma-assisted molecular-beam epitaxy growth on the structural and optical properties of InGaN nanostructures is studied. It is shown that cooling of the samples without nitrogen plasma contributes to the suppression of phase separation in InGaN nanostructures. The integrated intensity of photoluminescence from these nanostructures increased by a factor of 2.

In this work, we studied the influence of the III/V flux ratio on the structural and optical properties of InGaN nanowires grown by plasma-assisted molecular beam epitaxy. It was found that the formation of InGaN nanowires with a core–shell structure occurs if the III/V flux ratio is about 0.9–1.2 taking into account the In incorporation coefficient. At the same time, an increase in the III/V flux ratio from the intermediate growth regime to metal-rich one leads to a decrease in the In content in nanowires from ~45% to ~35%. This nanowires exhibit photoluminescence at room temperature with a maximum in the range of 600–650 nm. A further increase in the III/V flux ratio to ~1.3, or its decrease to ~0.4 leads to the formation of coalesced nanocolumnar layers with a low In content. The results obtained may be of interest for studying the growth processes of InGaN nanowires and creating RGB light-emitting devices on them.

In this study, for the first time, the influence of the III/V flux ratio on the structural and optical characteristics of InGaN nanowires grown by plasma-assisted molecular beam epitaxy are investigated. It is found that the formation of InGaN nanowires with a core–shell structure occurs when the III/V flux ratio (taking into account the In-incorporation coefficient) is about 0.9–1.2. At the same time, an increase in the III/V flux ratio from the intermediate growth conditions to metal-rich conditions leads to a decrease in the In content in nanowires from 45 to 35

This study investigates the growth of gallium arsenide nanowires, using lead as a catalyst. Typically, nanowires are grown through the vapor–solid–liquid mechanism, where a key factor is the reduction in the nucleation barrier beneath the catalyst droplet. Arsenic exhibits limited solubility in conventional catalysts; however, this research explores an alternative scenario in which lead serves as a solvent for arsenic, while gallium and lead are immiscible liquids. Liquid lead easily dissolves in Si as well as in GaAs. The preservation of the catalyst during the growth process is also addressed. GaAs nanowires have been grown by molecular beam epitaxy on silicon Si (111) substrates at varying temperatures. Observations indicate the spontaneous doping of the GaAs nanowires with both lead and silicon. These findings contribute to a deeper understanding of the VLS mechanism involved in nanowire growth. They are also an important step in the study of GaAs nanowire-doping processes.

For n-type doping of A3B5 semiconductors silicon are commonly used. However, Si in A3B5 nanowire is p-type dopant. Species are incorporated into nanowire through the intermediate liquid phase. Solubility of metals in catalyst are usually much more than nitrogen family elements. Nitrogen family elements easily dissolve in metal carbon family elements such as lead and tin. Here we discuss the growth of GaAs nanowires with lead catalyst on Si substrate. Lead could easily dissolve nitrogen family elements as well as boron family elements, which allows to switch nanowire growth from metal-rich to pnictide-rich growth.

The possibility of InP nanowhiskers growth from the saturated phosphorus and indium vapors with V/III ratio of 8–10 in a quasi-closed volume on (111) oriented silicon substrates with a natural oxide layer 2–2.5 nm has been demonstrated. The growth of InP nanowhiskers from Au-In-P catalytic droplets formed during the initial period is reported. Optical studies confirmed the formation of InP nanostructures upon the Si surface. The nanostructures exhibit a high doping level presumably with tin atoms.

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.

AlzGa1−zAs layers of various compositions were grown using metalorganic chemical vapor deposition on a GaAs substrate with a pattern of alternating SiO2 mask/window stripes, each 100 µm wide. Microphotoluminescence maps and thickness profiles of AlzGa1−zAs layers that demonstrated the distribution of the growth rate and z in the window were experimentally studied. It was shown that the layer growth rate and the AlAs mole fraction increased continuously from the center to the edge of the window. It was experimentally shown that for a fixed growth time of 10 min, as z increased from 0 to 0.3, the layer thickness difference between the center of the window and the edge increased from 700 Å to 1100 Å, and the maximum change in z between the center of the window and the edge reached Δz 0.016, respectively. Within the framework of the vapor -phase diffusion model, simulations of the spatial distribution of the layer thickness and z across the window were carried out. It was shown that the simulation results were in good agreement with the experimental results for the effective diffusion length D/k: Ga—85 µm, Al—50 µm.

The effect of cooling conditions in the plasma-assisted molecular-beam epitaxy growth on the structural and optical properties of InGaN nanostructures is studied. It is shown that cooling of the samples without nitrogen plasma contributes to the suppression of phase separation in InGaN nanostructures. The integrated intensity of photoluminescence from these nanostructures increased by a factor of 2.

AlGaAs nanowires with InAs quantum dots on the silicon surface were synthesized by molecular-beam epitaxy. Morphological and optical properties of grown nanostructures were studied. It is important to note, that emission from quantum dots is observed in the wavelength range from 780 to 970 nm. Assumptions about the nature of short-wave radiation from quan-tum dots were formulated. In particular, one of the reasons may be the significant desorption of indium atoms and the presence of gallium atoms in the catalyst droplets during growth at the substrate temperature of 510 degrees C. Our work, therefore, opens new prospects for integration of direct bandgap semiconductors with silicon platform.

An experimental study aimed at developing the method of the spontaneous synthesis of InGaN/GaN nanowires formed as radial heterostructures by molecular-beam epitaxy is reported. By means of electron microscopy, it is shown that a wedge-shaped crack can be formed at an In content x = 0.4 and 0.04 in the core and shell, respectively. On the basis of the model of internal structural stresses, a formula is proposed to estimate the critical dimensions and composition for the formation of cracks in nanowires. Comparison of the estimates with the experimental morphology data shows good agreement between them.

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.

Growth of hexagonal Ge stripes on the side facets of wurtzite AlGaAs and GaAs nanowires is considered. It is shown experimentally and explained within a model that Ge forms stripes on AlGaAs nanowires, while it covers conformally GaAs nanowires. The effect is explained by different surface and interface energies in the two material systems.

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.

The influence of the growth time on the structural properties of InGaN nanowires grown on Si substrate by plasma-assisted molecular beam epitaxy are studied. Under appropriate other growth conditions, the growth for 2h leads to the formation of separated nanowires, whereas the growth for 2h 30min and 3h leads to the formation of nanostructures such as nano-umbrellas. The separated NWs exhibit a photoluminescence spectrum with maxima at about 590 nm, whereas the nano-umbrellas show two pronounced photoluminescence lines at 421 and 619 nm.

The results of experimental studies concerned with the deposition of Ge onto the surface of AlGaAs nanowires are reported. The formation of both cubic and hexagonal Ge phases is detected by means of Raman spectroscopy. It is shown that thin Ge layers in the hexagonal phase are formed mainly on lateral surfaces of wurtzite-structured nanowires due to inheritance of the crystal structure.

We present the results on experimental studies of the directional radiation from GaAs quantum dots in AlGaAs nanowires grown by molecular beam epitaxy technique on silicon surface. It was shown that the radiation intensity from GaAs quantum dots in the direction of nanowires growth is 2 orders of magnitude higher than the intensity of radiation in the perpendicular direction.