Phase diagram of the GaAsSb system

Ishida, K.; Shumiya, T.; Nomura, Tadashi; Ohtani, Hiroshi; Nishizawa, Tsutomu

doi:10.1016/0022-5088(88)90170-1

Cited by 27 publications

(13 citation statements)

References 20 publications

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“…Thus, a relative change in these parameters will determine the Sb composition in the NWs for a given influx composition. Due to the lower volatility of Sb as compared to As, the decrease in Ψ Sb will be relatively higher than in Ψ As with a decrease in temperature, and the liquid-solid phase diagram of the GaAs-GaSb system also suggests that the K Sb /K As ratio will be higher 40 at lower growth temperatures. Consequently, the Sb composition in the NWs will be enhanced when grown at lower substrate temperatures, which is consistent with our experimental observations.…”

Section: Resultsmentioning

confidence: 99%

A Two-Step Growth Pathway for High Sb Incorporation in GaAsSb Nanowires in the Telecommunication Wavelength Range

Ahmad

Karim

Hafiz

et al. 2017

Sci Rep

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Self-catalyzed growth of axial GaAs1−xSbx nanowire (NW) arrays with bandgap tuning corresponding to the telecommunication wavelength of 1.3 µm poses a challenge, as the growth mechanism for axial configuration is primarily thermodynamically driven by the vapor-liquid-solid growth process. A systematic study carried out on the effects of group V/III beam equivalent (BEP) ratios and substrate temperature (Tsub) on the chemical composition in NWs and NW density revealed the efficacy of a two-step growth temperature sequence (initiating the growth at relatively higher Tsub = 620 °C and then continuing the growth at lower Tsub) as a promising approach for obtaining high-density NWs at higher Sb compositions. The dependence of the Sb composition in the NWs on the growth parameters investigated has been explained by an analytical relationship between the effective vapor composition and NW composition using relevant kinetic parameters. A two-step growth approach along with a gradual variation in Ga-BEP for offsetting the consumption of the droplets has been explored to realize long NWs with homogeneous Sb composition up to 34 at.% and photoluminescence emission reaching 1.3 µm at room temperature.

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Section: Resultsmentioning

confidence: 99%

A Two-Step Growth Pathway for High Sb Incorporation in GaAsSb Nanowires in the Telecommunication Wavelength Range

Ahmad

Karim

Hafiz

et al. 2017

Sci Rep

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“…The proposed phase diagram of the Ga‐containing skutterudites at 923 K is shown in Figure a, and is based on general knowledge of binary phase diagrams 51–55. The related binary phases of Ga, Co, and Sb are shown on the axes including the known regions of solid or liquid solubility for the binary compounds and a rough estimate of the solubility of the ternary compounds (red regions).…”

Section: Resultsmentioning

confidence: 99%

Charge‐Compensated Compound Defects in Ga‐containing Thermoelectric Skutterudites

Qiu

Shi

et al. 2013

Adv Funct Materials

112

106

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Heavy doping changes an intrinsic semiconductor into a metallic conductor by the introduction of impurity states. However, Ga impurities in thermoelectric skutterudite CoSb3 with lattice voids provides an example to the contrary. Because of dual‐site occupancy of the single Ga impurity charge‐compensated compound defects are formed. By combining first‐principle calculations and experiments, we show that Ga atoms occupy both the void and Sb sites in CoSb3 and couple with each other. The donated electrons from the void‐filling Ga (GaVF) saturate the dangling bonds from the Sb‐substitutional Ga (GaSb). The stabilization of Ga impurity as a compound defect extends the region of skutterudite phase stability toward Ga0.15Co4Sb11.95 whereas the solid–solution region in other directions of the ternary phase diagram is much smaller. A proposed ternary phase diagram for Ga‐Co‐Sb is given. This compensated defect complex leads to a nearly intrinsic semiconductor with heavy Ga doping in CoSb3 and a much reduced lattice thermal conductivity (κL) which can also be attributed to the effective scattering of both the low‐ and high‐frequency lattice phonons by the dual‐site occupant Ga impurities. Such a system maintains a low carrier concentration and therefore high thermopower, and the thermoelectric figure of merit quickly increases to 0.7 at a Ga doping content as low as 0.1 per Co4Sb12 and low carrier concentrations on the order of 1019 cm−3.

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“…Since in this system c,"&0, the energy c"ofa single cluster is lower than the energy of a phase exhibiting a few clusters. As the temperature is lowered, hence the entropy term -TbS becomes less important, the system acts to enrich 8 X"), hence reducing hH(x, T), as seen in Fig. 11.…”

Section: G Excess Cluster Probabilitiesmentioning

confidence: 88%

First-principles calculation of alloy phase diagrams: The renormalized-interaction approach

1989

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We present a formalism for calculating the temperature-composition phase diagrams of isostructural solid alloys from a microscopic theory of electronic interactions. First, the internal energy of the alloy is expanded in a series of volume-dependent multiatom interaction energies. These are determined from self-consistent total-energy calculations on periodic compounds described within the local-density formalism. Second, distant-neighbor interactions are renormalized into composition-and volume-dependent effective near-neighbor multisite interactions. Finally, approximate solutions to the general Ising model (using the tetrahedron cluster variation method) underlying these effective interactions provide the excess enthalpy AH, entropy hS, and hence the phase diagram. The method is illustrated for two prototype semiconductor fcc alloys: one with a large size mismatch (CxaAs"Sb& ) and one with a small size mismatch (Al& Ga As), producing excellent agreement with the measured miscibility temperature and excess enthalpies. For latticernismatched systems, we find 0 & hH & AH, where 0 denotes some ordered Landau-Lifshitz (LL)structures, and D denotes the disordered phase. We hence predict that such alloys will disproportionate at low-temperature equilibrium into the binary constituents, but if disproportionation is kinetically inhibited, some special ordered phases (i.e., chalcopyrite) will be thermodynamically stabler below a critical temperature than the disordered phase of the same composition. For the lattice-matched systems, we find 0&EH &AH for all LL structures, so that only a phaseseparating behavior is predicted. However, in these systems, longer-period ordered superlattices are found to be stabler, at low temperatures, than the disordered alloy.

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Phase diagram of the GaAsSb system

Cited by 27 publications

References 20 publications

A Two-Step Growth Pathway for High Sb Incorporation in GaAsSb Nanowires in the Telecommunication Wavelength Range

A Two-Step Growth Pathway for High Sb Incorporation in GaAsSb Nanowires in the Telecommunication Wavelength Range

Charge‐Compensated Compound Defects in Ga‐containing Thermoelectric Skutterudites

First-principles calculation of alloy phase diagrams: The renormalized-interaction approach

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