Fractionally charged magnetoelectron (anyon) complexes formed by the creation of magnetic flux quanta vortices in single-electron states are detected in a three-electron Wigner quantum dot (Wigner-Seitz radius ) using low-temperature (30 K) magnetophotoluminescence spectroscopy measurements. In zero magnetic field, vortices induce their own field , so such vortices and corresponding complexes can be identified as elementary magnetic poles and Dirac anyons (DAs), respectively. In this quantum dot, DA structures with an average number of vortices per electron from 3 to 2/5 and B from -7 to 0 T were identified in the magnetic field range . Spectral data and calculations of electron density distributions using the configurational interaction approach show that at T the structures are triangular molecules with a side of nm and a DA size of similar to 30 nm, whereas at higher field it is a DA puddle of similar to 80 nm, and thus the molecular states are suppressed by the strong magnetic field. The recognition of magnetoelectron complexes as DAs and the observation of the molecular-puddle transition in the DA composites induced by a magnetic field in Wigner quantum dots are important steps in the investigation of these unique magnetoelectronic quantum states that can be exploited in anyon-based quantum computing. We also show the connection of DAs with the quantum Hall effect states, which clarifies unresolved issues in their description.

The possibility of manufacturing photovoltaic converter structures due to solid-phase reactions of substitution of Sb atoms in GaSb semiconductor wafers with As or P atoms, with simultaneous diffusion of Zn, is demonstrated.

The results of investigations by the method of Electron beam-induced current of p-n-junctions based on InP with GaP crystallites in the space charge region are presented. It is shown that the introduction of crystallites into the space charge region leads to short-circuiting of the p-n-junction. The quality of the material grown on top of the crystallites allows to create of photoactive regions, as evidenced by measurements of the photoluminescence spectra. Keywords: crystallites, tunnel junction, connecting element.

The technology for production one and two-cascade power laser converters was presented in this paper. According to the measurement results of the grown samples, an efficiency of 34.5

Thick smoothly graded Al x Ga 1−x As layers (50–100 µm) are used in light-emitting diode structures and also for creation of high-power photovoltaic converters with side-input of laser radiation. To achieve the required thickness of the Al x Ga 1−x As layer the high temperature LPE growth technique is required. However high epitaxial temperature increases the unintentional doping level. Epitaxy from mixed Ga-Bi melts was investigated as a way to solve this problem. It was found that for growing relatively thick Al x Ga 1−x As layers, it is expedient to use Ga-Bi melts with 20 at.% or less bismuth content. SIMS and Hall characterization of Al x Ga 1−x As layers revealed that the growth of Al x Ga 1−x As from mixed Ga-Bi melts reduces the background doping level (including carbon) and influences the native defect formation keeping the n-type conductivity. This effect is explained by the changes of the group III and V elements concentrations in the melt as well as Bi incorporation in the lattice.

Experiments on the growth of self-assembled InP/GaInP2 quantum dots in dielectric mask 0.1–1 μm apertures by MOVPE epitaxy have been carried out. A sequence of operations for the implementation of the lift-off lithography method is proposed and implemented. The possibility of obtaining apertures with 100 nm diameter and less is shown. Combination of thermally deposited SiO2 and wet etching is shown to produce minimal amount of nonradiative defects and results in a stable PL signal from single QDs in the aperture.

The effect of lattice relaxation instability (martensitic transition) on piezoelectric fields (EPE) in spontaneously ordered GaInP2/GaAs epitaxial layers was demonstrated using scanning Kelvin probe microscopy in combination with electron microscopy and optical spectroscopy measurements. The transition manifests itself in the dependence of the surface potential of the epi-layer on the mechanical (cleavage) and thermal (annealing) impacts. This is associated with a switching of the crystal lattice between relaxed and strained martensitic states, corresponding to a change in EPE in the epi-layer. The measured surface potential values (0.2–2.4 V) correspond to EPE within ±100 kV/cm and a strong decrease in |EPE| with increasing layer thickness, indicating the pinning of the Fermi level and piezoelectric doping. Our results open up the prospects for using spontaneously ordered semiconductor alloys to control electronic states in semiconductor nanostructures by controlling their piezoelectric fields.

Thick smoothly graded AlxGa1−xAs layers (50–100 µm) are used in light-emitting diode structures and also for creation of high-power photovoltaic converters with side-input of laser radiation. To achieve the required thickness of the AlxGa1−xAs layer the high temperature LPE growth technique is required. However high epitaxial temperature increases the unintentional doping level. Epitaxy from mixed Ga–Bi melts was investigated as a way to solve this problem. It was found that for growing relatively thick AlxGa1−xAs layers, it is expedient to use Ga–Bi melts with 20 at% or less bismuth content. SIMS and Hall characterization of AlxGa1−xAs layers revealed that the growth of AlxGa1−xAs from mixed Ga-Bi melts reduces the background doping level (including carbon) and influences the native defect formation keeping the n-type conductivity. This effect is explained by the changes of the group III and V elements concentrations in the melt as well as Bi incorporation in the lattice.

The growth of thick (more than 50 μm) AlxGa1 – xAs gradient layers in the Al–Ga–As–Sn system has been modeled. Sn-doped AlxGa1 – xAs layers up to 85 μm thick were obtained by liquid-phase epitaxy. The obtained experimental profiles of the AlxGa1 – xAs composition gradient satisfy the used theoretical model for the cases of growth from a limited volume of a solution–melt.

Solidus and liquidus isotherms in the Al–Ga–As–Bi system have been modeled for an initial epitaxy temperature of 900°C, which is needed for growing relatively thick (50–100 μm) compositionally graded AlxGa1–xAs layers. The theoretical isotherms have been confirmed by experimental data. It has been shown that, to grow relatively thick (>50 μm) AlGaAs layers, it is reasonable to use Ga–Bi mixed melts containing no more than 20 at

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.

✉ gruzaa01@gmail.com Abstract. We used the photoluminescence spectra of a single InP/GaInP2 quantum dot with a Wigner-Seitz radius of about 3.4, doped with 4 electrons, to measure the magnetic field dispersion of single quantum states in a range between 0 , 10 T at 30 K. The measurements show the formation of a molecular structure at high temperature and its transition to a pud-dle-like structure with a decrease of localization size from 110 nm to 70 nm. Fock-Darwin spectrum fitting shows a decrease in the cyclotron frequency and magnetic field shift, that are interpreted as the formation of an anyon structure in a QD with fractional charge 1/5, 2/3, 1/2 and a built-in magnetic field of -3T.

The development of GaAs based high power side-input photovoltaic converters requires thick (50-100 mu m) transparent gradient refraction layers that can be grown by liquid phase epitaxy. Such thick layers can also be used in LED structures. To solve the problem of AlxGa1-xAs conductivity reduction at the x similar to 40% point a five-component, Al-Ga-As-Sn-Bi system is proposed. The interaction parameters in the liquid phase (alpha ij) in the Al-Ga-As-Sn-Bi system are determined within the framework of a quasi-regular solutions model. For an AlxGa1-xAs solid solution growing from a Ga-melt containing 10 at.% of Bi (as a neutral solvent) and 15 at.% of Sn (as an n-type dopant), liquidus and solidus isotherms for 900 degrees C are modeled based on the calculated alpha ij. Satisfactory agreement between calculated and experimental data has been obtained. Hall data show that AlGaAs layers grown from Bi-containing melts have n-type conductivity. Doping by tin during growth from mixed Ga-Bi melts makes it possible to increase the electron concentration in the AlGaAs layer.

Для начальной температуры эпитаксии 900°C, которая необходима для выращивания относительно толстых градиентных слоев Al x Ga 1– x As (50–100 мкм), были смоделированы изотермы солидусa и ликвидусa в системе Al–Ga–As–Bi. Теоретические изотермы подтверждены экспериментальными данными. Обнаружено, что для выращивания толстых (более 50 мкм) слоев AlGaAs целесообразно использовать смешанныe Ga–Bi-расплавы с содержанием висмута не более 20 ат. %.

We report non-contact local doping of a monolayer WSe2 transferred onto a piezoelectric substrate having surface potential wells (SPWs) induced by structural inhomogeneities. We used epitaxial GaN and InP/GaInP2 structures, in which there are SPWs ∼0.2 V deep and 0.1–2 μm in size. Using surface topography and potential scanning probe microscopy, as well as optical reflectance, photoluminescence, and Raman spectroscopy measurements, we observed strong enhancement of charged exciton emission and Raman intensity in the SPW regions of the monolayer WSe2, which indicate on piezoelectric doping at a level n ≥ 1012 cm−2 on a length scale ∼0.2–1 μm. Our results can be used to create electron/hole quantum puddles with anyon states in transition metal dichalcogenides, promising for the development of room temperature and magnetic-field-free fault-tolerant topological quantum computing.

The characterization of Si-doped GaSb epitaxial layers, grown by metal-organic vapor-phase epitaxy at a constant SiH4 flow with a TMSb/TEGa ratio ranging from 1 to 50, is presented. X-ray diffraction rocking curves, photoluminescence spectra, Raman scattering spectra, resistivity, concentration of free carriers, and their mobility in GaSb:Si layers are analyzed.

We demonstrate non-contact local doping of a monolayer WSe2 transferred onto a piezo-electric substrate having structural inhomogeneities using surface topography and potential scanning probe imaging along with photo-luminescence (PL) and Raman spectra mapping. We used a GaN epilayer grown by molecular beam epitaxy, in which surface potential wells having the depth of ~0.2 V and the size of ~1 μm, induced by inversion domains and Ga droplets are formed. In the monolayer WSe2 flake mechanically exfoliated on the epilayer, we observed a strong enhancement of the trion emission and the A1g phonon Raman intensity in the well region, which indicate a local piezo-electric doping of WSe2 at a level n>1012 cm-2. We show that our results can be used to create quantum Hall puddles having fractionally charged magneto-electron/anyon states at room temperature, which are promising for the development of fault-tolerant topological quantum computing.

In magneto-photoluminescence (magneto-PL) spectra of quasi two-dimensional islands (quantum dots) having seven electrons and Wigner–Seitz radius rs~1.5, we revealed a suppression of magnetic field (B) dispersion, paramagnetic shifts, and jumps of the energy of the emission components for filling factors ν > 1 (B < 10 T). Additionally, we observed B-hysteresis of the jumps and a dependence of all these anomalous features on rs. Using a theoretical description of the magneto-PL spectra and an analysis of the electronic structure of these dots based on the single-particle Fock–Darwin spectrum and many-particle configuration-interaction calculations, we show that these observations can be described by the rs-dependent formation of the anyon (magneto-electron) composites (ACs) involving single-particle states having non-zero angular momentum and that the anyon states observed involve Majorana modes (MMs), including zero-B modes having an equal number of vortexes and anti-vortexes, which can be considered as Majorana anyons. We show that the paramagnetic shift corresponds to a destruction of the equilibrium self-formed ν~5/2 AC by the external magnetic field and that the jumps and their hysteresis can be described in terms of Majorana qubit states controlled by B and rs. Our results show a critical role of quantum confinement in the formation of magneto-electrons and implies the liquid-crystal nature of fractional quantum Hall effect states, the Majorana anyon origin of the states having even ν, i.e., composite fermions, which provide new opportunities for topological quantum computing.

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.