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.

Samples of heterostructures made on the basis of semiconductor wafers of binary compounds GaAs, GaSb and InAs as a result of substitution of Group V elements of atoms by atoms of other Group V elements supplied in the form of vapors, including simultaneous Zn diffusion are studied. The possibility of using the obtained structures to make a photoelectric converter is demonstrated.

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 possibility of manufacturing semiconductor heterostructures based on III–V compounds for photovoltaic converters by diffusion methods is investigated. In a semiconductor wafer of the AB compound, a near-surface nanoscale layer of AB1 – xCx solid solution is formed due to the solid-phase substitution reactions of B atoms with C atoms supplied to the surface of the wafer in vapor form at 480–580°C for GaSb wafers and 670°C for GaAs wafers. The source of the C-element vapor were saturated solution melts based on Ga or In, or unsaturated Sn-based solution melts. The possibility of forming a p–n junction due to Zn diffusion into the n-type AB wafer simultaneously with the formation of an AB1 – xCx near-surface layer is investigated. The positive effect of GaSb1 – xAsx and GaSb1 – xPx near-surface layers on the luminescence characteristics of GaSb-based structures with simultaneous zinc diffusion is shown.

In the study of doped anisotypic heterostructures with layers of Ga(1-x)In(x)P(1-y)As(y) grown on InP substrates with a buffer layer of InP by MOC-hydride epitaxy, the presence of transition regions was detected in the Ga(1-x)In(x)P(1-y)As(y) layer on the substrate side for individual samples, across which the arsenic content (y) increased from the interface with the InP layer to the surface of the structure by the amount of (Δy) up to 0.15, and the content of elements of the third group (x) remained constant.

When studying doped anisotypic heterostructures with Ga1 – xInxAsyP1 – y layers grown on InP substrates with an InP buffer layer by metal organic chemical vapor deposition, the presence of transition regions is revealed in the Ga1 – xInxAsyP1 – y layer from the side of the substrate in some of the samples, along which the arsenic content (y) increases from the interface with the InP layer to the surface of the structure by a Δy value of up to 0.15, while the content of elements of the third group (x) remains constant.

Luminescence properties of epilayers of Ga 1 – x In x As y P 1 – y (GaInAsP) solid solutions with graded content of Group V elements (Δ y up to 0.08 over a total thickness of about 1 μm) were studied at 77 and 300 K. The photoluminescence (PL) spectra of GaInAsP epilayers with large Δ y values were broadened. The GaInAsP epilayers of low crystalline perfection exhibited either no PL emission or showed PL spectra characteristic of transitions involving impurity energy levels.

The photoluminescent properties at 77 and 300 K are investigated for Ga1 xInxAsyP1 y epilayers with V-group elements content gradient Δy up to 0.08 across whole thickness (about 1 µm). Ga1 xInxAsyP1 y layers with high Δy values have widened photoluminescence spectra. For GaInAsP layers of low crystaline perfection, photoluminescence was either absent or manifested itself as it is typical for transitions involving impurity levels.

GaInPAs/InP heterostructures grown by low pressure (0.1 bar, 600 oC) metal-organic chemical vapor phase deposition were investigated. The thicknesses of grown GaInAsP layers were about 1 µm. For the epitaxial layers Ga1-xInxP1-yAsy) with average compositions of x = 0.77 – 0.87 and y = 0.07 – 0.42 the variation of V group elements content y with the epilayer depth were revealed, weher the compositions of V-group elements were changed up to Δy = 0.1 atomic fractions in V group elements sublattice. In most cases, y change occurs in a GaInAsP region up to 200 nm thick adjacent to the InP. In some cases, y changes throughout the whole GaInPAs layer thickness. Fo the epitaxial layers with a satisfactory crystal perfection the less was the mismatch between the substrate and the GaInPAs epitaxial layer, the smaller was the value of Δy. For GaInPAs layers characterized by a low degree of crystal perfection and a high lattice mismatch between GaInAsP and InP layers, the value of Δy was about zero. These data let us suggest that the incorporation of atoms of the V group in the epitaxial layer strongly depends on elastic deformation of the growing monolayer, that is mismatched with the underlying crystal surface.

GaInPAs/InP heterostructures grown by metalorganic chemical vapor-phase deposition at a temperature of 600°C and pressure of 0.1 bar are investigated. The thicknesses of the grown GaInAsP layers amount to about 1 μm. For Ga1 –xInxP1 –yAsy solid solutions with average compositions of x = 0.77–0.87 and y = 0.07–0.42, the variation in the content y of V-group atoms over the epitaxial-layer thickness by a value of Δy up to 0.1 atomic fractions in the sublattice of the V-group elements is revealed by secondary ion mass spectrometry. In most cases, a change in y occurs in the GaInAsP layer over a length to 200 nm from the InP heterointerface. In certain cases, y varies throughout the entire GaInPAs-layer thickness. For the epitaxial layers with satisfactory crystalline perfection, the value of Δy is less in the case of better lattice-matching between the GaInPAs epitaxial layer and the substrate. For GaInPAs layers strongly lattice-mismatched with the substrate and characterized by a low degree of crystalline perfection, the value of Δy is close to zero. All these facts enable us to assume that it is elastic deformations arising in the forming monolayer lattice-mismatched with the growing surface that affect the incorporation of V-group atoms into the forming crystalline lattice.

Gradual variation of the content y of Group-V components by Δy of up to 0.08 across the thickness (600–850 nm) of an epitaxial layer has been observed for Ga1 – xInxAsyP1 – y solid solutions (x = 0.86, y = 0.07–0.42) produced on InP by metal-organic vapor-phase epitaxy under lowered pressure, although the composition of the gas mixture, temperature, and pressure were maintained invariable in the course of the growth process. For different gas mixture compositions, the value of Δy and the manner of its variation were different. An analysis of the data obtained demonstrated that Δy is due to the deformations that appear in a growing layer because of the lattice mismatch with the substrate.

Ga1-xInxAsyP1−y epitaxial layers with compositions x = 0.77 − 0.87, y = 0.07 − 0.42 and thicknesses 620 − 850 nm were grown by MOCVD method on InP substrates. Temperature, pressure and gas mixture composition were held constant during growth procedure. Secondary-ion mass spectrometry showed change of V-group elements composition y through epilayers thicknesses by value Δy up to 0.08. Reducing Δy value down to 0.01 − 0.02 was achieved by optimizing the composition of gas mixture to reduce lattice mismatch between the layer and the substrate. The obtained data allow us to conclude that the deformations arising due to lattice mismatch between the forming layer and the growth surface result in varying the content of V-group elements through epilayer thickness.

При исследовании полученных методом газофазной эпитаксии гетероструктур InAsxPySb1-x-y/InAs (x>0.55) для рассогласованных с подложкой образцов методом вторичной ионной масс-спектрометрии выявлено заметное и протяженное (~800 nm) изменение содержания As и P (y до 0.12) по толщине слоя, носящее экспоненциальный характер. Рассчитанное по измеренному распределению компонентов As и P несоответствие параметров решеток было максимальным на границе эпитаксиального слоя с подложкой и уменьшалось по мере удаления от гетероинтерфейса в глубь эпитаксиального слоя. DOI: 10.21883/PJTF.2017.19.45085.16810

A study by secondary-ion mass spectrometry of InAs x P y Sb1–x–y/InAs heterostructures (x > 0.55) grown by vapor-phase epitaxy for lattice-mismatched with substrates samples revealed a noticeable and extended (~800 nm) exponential variation of the As and P content (y up to 0.12) across the layer thickness. The lattice mismatch calculated from the experimentally determined distribution of the As and P components was the strongest at the interface between the epitaxial layer and the substrate and decreased away from the heterointerface into the epitaxial layer.

Processes are considered in which ultrathin layers of III–V ternary solid solutions are formed via the delivery of Group-V element vapors to GaAs and GaSb semiconductor plates, with solid-phase substitution reactions occurring in the surface layers of these plates. This method can form defect-free GaAs1–xPx, GaAsxSb1–x, and GaPxSb1–x layers with thicknesses of 10–20 nm and a content x of the embedded components of up to 0.04.

A new method based on solid-state substitution reactions is proposed for obtaining nanodimensional layers of GaAsP solid solutions on the surface of GaAs semiconductor crystals. The processed GaAs wafers exhibit a wide-bandgap optical window effect, whereby their room-temperature photoluminescence intensity increases by a factor of up to 25.

Processes of epitaxial growth of narrow-bandgap (with bandgap value E g ≈ 0.3−0.48 eV) solid solutions GaInAsSb and InAsPSb on InAs substrates by metal-organic chemical vapor deposition at low pressure (76 Torr) are investigated. It is shown that, under chosen growth conditions, the InAsPSb epilayers have high crystalline quality, while the solid solutions Ga1−x In x As y Sb1−y and InAs y P z Sb1 − y − z have compositions close to InAs (0.86 < x < 0.93, 0.62 < y < 0.9, 0.17 < z < 0.26) and manifest photoluminescence at room temperature.

Epitaxial growth of Al u Ga 1 − u − x In x As y Sb 1 − y and Al u Ca 1 − u As y Sb 1 − y solid solutions has been investigated. Epitaxial layers with the compositions 0.02 < u < 0.11, 0.88 < x < 0.93, and 0.88 < y < 0.98 have been grown on InAs substrates by metal-organic vapor-phase epitaxy at low pressure (76 Torr) and at the ratio of the sum of partial pressures of compounds of fifth-group elements to that for compounds of third-group elements V/III = 3.6–6. At a lattice mismatch of 1 × 10 −3 , the half-widths of the rocking curves for the best samples were 15 arcsec for substrates and 66 arcsec for layers.

The composition of galkhaite from the Gal-Khaya deposit (Yakutia, Russia) and Chauvay Mine (Kyrgyzstan) has been examined by electron microprobe. A significant Cs content (up to 6.64 wt %) has been established in the mineral from both deposits; earlier, it had been not detected by either chemical or spectral analyses. The empirical formulas of galkhaite are (Hg4.89Cu0.92Zn0.07)5.88(Cs0.71Tl0.17)0.88(As3.98Sb0.17)4.15 S12.10 and (Hg4.64Cu0.98Zn0.34)5.96 (Cs0.85Tl0.04)0.89(As3.68Sb0.42)4.10S12.05 at the Gal-Khaya deposit and Chauvay Mine, respectively. The crystal structure of galkhaite from the Chauvay Mine (cubic, I43m, a = 10.4144(1) Å, V = 1129.5(2) Å3, Z = 2) for the composition [Hg4.83(Cu,Zn)0.98□](Cs0.71Tl0.14□) (As3.44Sb0.56)S12 has been determined by direct methods and refined to R = 0.0203. The structure of galkhaite is a framework consisting of vertex-shared [(Hg,Cu)-S4 2.5068(3) Å] tetrahedrons of the same orientation as large cavities formed in the initial sphalerite structural type due to eight anion vacancies: two [S4]-tetrahedrons at the point of origin and at the center of the I-cell and 12 cation vacancies as 2 cation octahedrons around the 000 and \( {\raise0.5ex\hbox{$\scriptstyle 1$} \kern-0.1em/\kern-0.15em \lower0.25ex\hbox{$\scriptstyle 2$}}{\raise0.5ex\hbox{$\scriptstyle 1$} \kern-0.1em/\kern-0.15em \lower0.25ex\hbox{$\scriptstyle 2$}}{\raise0.5ex\hbox{$\scriptstyle 1$} \kern-0.1em/\kern-0.15em \lower0.25ex\hbox{$\scriptstyle 2$}} \) sites.

An X-ray diffraction study of mineral livingstonite (HgSb 4 S 8 ) from Khaydarkan (Kyrgyzstan) has been performed on a Bruker Nonius X8Apex diffractometer with a 4K CCD detector ( R = 0.031). The unit-cell parameters were found to be a = 30.1543(10) Å, b = 3.9953(2) Å, c = 21.4262(13) Å, β = 104.265(1)°, V = 2501.7(2) Å 3 , Z = 8, d calcd = 5.013 g/cm 3 , and sp. gr. A 2/ a . It was confirmed that livingstonite belongs to rod-layers structures. In one type of layer, two double Sb 2 S 4 chains are bound by disulfide groups [S 2 ] 2− (S-S 2.078(2) Å); in the other type, these chains are bound via Hg 2+ cations. A crystallographic analysis confirmed the existence of independent pseudotranslational ordering in the cation and anion matrices, which is characteristic of the lozenge-like structures of sulfides and sulfosalts.