Crystal growth of GaSb under microgravity conditions (original) (raw)
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The growth of GaSb under microgravity conditions
Journal of Crystal Growth, 1985
A high quality GaSb bicrystal was grown in a Bridgman type arrangement under microgravity conditions on board of Salyut-6. Rutherford back-scattering measurements indicate oxide and damage free surfaces. Scanning Electron Microscopy revealed microfacets on the space grown sample. The morphology of the sample suggests a crystallization quite free of a wall effect. A comparison is given between space and terrestrial GaSb ingots, showing differences in surface quality, crystal perfection and hole mobilities. In the space grown sample a l% ~ 2700 cm 2 v-1 s-1 value was found while for the terrestrial control this value was only 2000 cm 2 v-1 s-1
Growth and characterization of shaped GaSb crystals
Journal of Crystal Growth, 2000
Shaped GaSb crystals (ribbons and rods) were grown by pulling from the melt using a non-wetted #oating shaper to control the crystal cross-section shape and size. Graphite, which does not react chemically with molten gallium antimonide, has been chosen as shaper and crucible material. Etch pit density and electrical properties of the ribbons were determined.
Microgravity growth of GaSb single crystals by the liquid encapsulated melt zone (LEMZ) technique
Journal of Crystal Growth, 1999
A liquid encapsulated melt zone (LEMZ) technique was used to grow [1 0 0] GaSb single crystals under microgravity conditions aboard the STS-77 Shuttle Endeavor mission. One tellurium-doped and two undoped single crystals, encapsulated in a eutectic mixture of sodium chloride and potassium chloride, were regrown from 16 mm diameter single-crystal rods at translation speeds ranging from 1 to 6 mm/h. The quality of the crystals was compared to those grown on ground using the LEMZ technique at translation speeds ranging from 3 to 18 mm/h. It was found that the microgravity-grown crystals, particularly the Te-doped crystal, exhibited lower dislocation densities than those grown on ground. The dislocation density was also found to depend on the solid/liquid interface shape with a planar interface resulting in a lower density. Reduction of rotational and nonrotational striations was obtained with the encapsulation technique in all crystals. Moreover, the use of the encapsulant allowed for longer and more stable melt zones for those samples processed on ground.
Compositional and structural characterisation of GaSb and GaInSb
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2005
Low band gap III-V semiconductors are researched for applications in thermophotovoltaic technology. GaSb crystal is often used as a substrate. Ga 1Àx In x Sb is also a promising substrate material, because its lattice parameters can be adjusted by controlling x. We used a new method to synthesise GaSb and GaInSb, in which a high frequency alternate magnetic field is used to heat, to melt and to mix the elements. We present a compositional and structural characterisation of the materials using a combination of complementary techniques. Rutherford backscattering was used to determine accurately the composition of the GaSb. With proton induced X-ray emission in conjunction with a 3 · 3 lm 2 micro-beam we studied the homogeneity of the samples. Structural analysis and phase identification were done with X-ray diffraction. The results for GaSb show a homogeneous composition while the GaInSb samples were found to be strongly heterogeneous at the end of the ingot. The ingots produced are competitive feed material, when compared to other growth techniques, to be used in a second step for the production of good quality ternary crystals.
More progressive technology of GaSb single crystal growth
Czechoslovak Journal of Physics - CZECH J PHYS, 1997
GaSb single crystals were grown by the Czochralski method without encapsulant in an atmosphere of ionized hydrogen. It has been found that the resistivity increased by more than one order of magnitude (0.8 1.0Omega cm) and free carrier concentration decreased to the value of (1 2) × 1016 cm-3 in comparison with the crystals grown under molecular hydrogen atmosphere. A certain asymmetry in acceptor and donor passivation is assumed because the Hall concentration does not vary along the direction of crystal growth. Donors are passivated more than acceptors, which should be confirmed by increasing resistivity and decreasing mobility.
Journal of Crystal Growth, 2007
Results of ground-based experiments on crystallization of gallium antimonide on the POLIZON facility carried out within the framework of space experiment preparation aboard FOTON satellite are submitted. Technical and technological opportunities of suppression of disturbing factors for improvement of quality of grown crystals in space are substantiated. Features of formation of concentration and structure inhomogeneities in GaSb:Si crystals grown under non-stationary and stationary convection conditions are investigated. Experimental data about structure and dopant distribution inhomogeneities are discussed taking into account results of numerical researches of GaSb:Si crystallization. Also earlier received results of modeling of GaSb:Te crystallization under close temperature conditions are used. Correlation between computational and experimental data is shown. The data on intensity of flows close to crystallization front are received at which non-stationary or stationary conditions of crystallization are realized. The forecast for space conditions is made. The influence of a rotating magnetic field on convection in melt for application in space experiment projected is investigated.
npj Microgravity, 2016
InGaSb ternary alloys were grown from GaSb (111)A and B faces (Ga and Sb faces) under microgravity conditions on board the International Space Station by a vertical gradient freezing method. The dissolution process of the Ga and Sb faces of GaSb and orientation-dependent growth properties of InGaSb were analysed. The dissolution of GaSb(111)B was greater than that of (111)A, which was found from the remaining undissolved seed and feed crystals. The higher dissolution of the Sb face was explained based on the number of atoms at that face, and its bonding with the next atomic layer. The growth interface shape was almost flat in both cases. The indium composition in both InGaSb samples was uniform in the radial direction and it gradually decreased along the growth direction because of segregation. The growth rate of InGaSb from GaSb (111)B was found to be higher than that of GaSb (111)A because of the higher dissolution of GaSb (111)B.
Decrease in free carrier concentration in GaSb crystals using an ionized hydrogen atmosphere
Materials Chemistry and Physics, 1996
GaSb single crystals were grown under a flow of ionized hydrogen using the Czochralski method without encapsulant. The optimal position of a deuterium lamp was studie'd, and it has been found that the lamp position is not the main factor, in principle. However, better results were achieved in the case of the lamp position being several millimeters above the solid/liquid interface. In addition, it seems to be very likely that donors are passivated more than acceptors, which is confiimed by the growth of Te-doped GaSb. The low Te-doped crystals were p-type in the whole volume, and the free carrier concentration was almost the same and very homogeneous from the top to the bottom of the GaSb crystal, 1.8-2.3 x 1016 cmW3.
Structural Characterization of Doped GaSb Single Crystals by X-ray Topography
Journal of Electronic Materials, 2010
We characterized GaSb single crystals containing different dopants (Al, Cd and Te), grown by the Czochralski method, by x-ray topography and high angular resolution x-ray diffraction. Lang topography revealed dislocations parallel and perpendicular to the crystal's surface. Double-crystal GaSb 333 x-ray topography shows dislocations and vertical stripes than can be associated with circular growth bands. We compared our high-angular resolution x-ray diffraction measurements (rocking curves) with the findings predicted by the dynamical theory of x-ray diffraction. These measurements show that our GaSb single crystals have a relative variation in the lattice parameter (Δd/d) on the order of 10-5. This means that they can be used as electronic devices (detectors, for example) and as x-ray monochromators.
Dislocations and dislocation reduction in space grown GaSb
Crystal Research and Technology, 2009
The behaviour of dislocations in GaSb crystals grown in space both from a stoichiometric melt (floating zone method, FZ) and a Bi solution (floating solution zone, FSZ) respectively, is studied. Predominantly straight 60° dislocations with Burgers vectors of the type b = a/2 <110> in (111) glide planes are identified. In the 20 mm long FZ single crystal the linear growing out of the dislocations is observed which reduces the dislocation density in the centre of the crystal to values below 300 cm -2 . The Bi incorporation in the FSZ crystal results in a misfit between seed and grown crystal and in a network of misfit dislocations at the interface. Thermocapillary convection during growth as well as the surface tension may be the reasons for the presence of curved dislocations and the higher dislocation density within a 1 -2 mm border region at the edges of both of the crystals.