Investigation of directionally solidified InGaSb ternary alloys from Ga and Sb faces of GaSb(111) under prolonged microgravity at the International Space Station

Kumar, V. Jawahar Senthil; Arivanandhan, M.; Rajesh, Govindasamy; Koyama, Tadanobu; Momose, Yoshimi; Sakata, Koichi; Ozawa, Tomohiro; Okano, Yasunori; Inatomi, Yuko; Hayakawa, Y.

doi:10.1038/npjmgrav.2016.26

Cited by 12 publications

(3 citation statements)

References 27 publications

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“…In the <111> direction, the atomic structure of the semiconductor is an alternation of atomic layers of Ga and Sb, and the [111] and [111] directions are nonequivalent (Figure 1b,c). In accordance with commonly used notation of the A III B V surface with {111} orientation (e.g., [34]), the Ga-terminated (111) surface is called GaSb(111)A, and the Sbterminated (111) one -GaSb(111)B. In the present calculation, the GaSb(111) -(1 × 1) surface was simulated by eight-layer films.…”

Section: Computational Detailsmentioning

confidence: 99%

Role of Oxygen and Fluorine in Passivation of the GaSb(111) Surface Depending on Its Termination

et al. 2022

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The mechanism of the chemical bonding of oxygen and fluorine on the GaSb(111) surface depending on its termination is studied by the projector augmented-waves method within density functional theory. It is shown that on an unreconstructed (111) surface with a cation termination, the adsorption of fluorine leads to the removal of surface states from the band gap. The binding energy of fluorine on the cation-terminated surface in the most preferable Ga-T position is lower by ~0.4 eV than that of oxygen, but it is significantly lower (by ~0.8 eV) on the anion-terminated surface. We demonstrate that the mechanism of chemical bonding of electronegative adsorbates with the surface has an ionic–covalent character. The covalence of the O–Sb bond is higher than the F–Sb one, and it is higher than both O–Ga and F–Ga bonds. Trends in the change in the electronic structure of the GaSb(111) surface upon adsorption of fluorine and oxygen are discussed. It is found that an increase in the oxygen concentration on the Sb-terminated GaSb(111) surface promotes a decrease in the density of surface states in the band gap.

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Section: Computational Detailsmentioning

confidence: 99%

Role of Oxygen and Fluorine in Passivation of the GaSb(111) Surface Depending on Its Termination

et al. 2022

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“…However, the non-degenerate conduction band and alloy ordering in the InSb-rich compositions indicated a complex correlation between the optical and electrical parameters [27]. The ternary InGaSb alloys grown under microgravity conditions at the International Space Station using a vertical gradient freezing technique were used to analyze the dissolution at two different faces of GaSb [28].…”

Section: Introductionmentioning

confidence: 99%

Engineering of the band gap and optical properties of In_xGa_1−x(As/Sb) via across composition alloying for solar cell applications using density functional theory-based approaches

et al. 2019

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The optoelectronic properties of InxGa1−x(As/Sb) are analyzed using density functional theory by employing a modified potential scheme of Trans and Blaha as developed in WIEN2k code. The indium doping in GaAs and GaSb tune the band gap from 1.56 to 0.43 eV and 0.82 to 0.30 eV, respectively, which highlights their significance for solar cell related applications. The optical characteristics are assessed by studying the dielectric constant, refraction, absorption, optical conductivity and optical loss of light energy. The static dielectric constant related to the optical band gap through Penn’s model and with static refractive index = n2(0) increase consistently between the calculated results. The maximum absorption and small optical loss factor for visible to near UV regions can enhance the optical efficiency for solar cell and optoelectronic applications. Moreover, higher optical conductivity within 3.5–4.5 eV allows forward current, which is attractive for practical applications.

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“…An understanding of the formation of defects in crystalline materials requires a knowledge of nucleation kinetics during their growth process. Our research group performed various growth experiments under normal and microgravity conditions to understand the nucleation kinetics of InGaSb ternary alloys. − InGaSb is a III–V ternary alloy whose thermoelectric properties are yet to be understood well. The thermal conductivities of some significant III–V semiconductors such as InSb, InAs, GaSb, GaAs, and AlAs were around 17.5, 30, 36, 45, and 91 W/mK, respectively. , However, the highly efficient TE materials (ZT > 1) possess thermal conductivity less than 1 W/mK. − Thus, the III–V semiconductors have at least one order of higher magnitude of thermal conductivity when compared to other efficient TE materials.…”

Section: Introductionmentioning

confidence: 99%

An Approach to Optimize the Thermoelectric Properties of III–V Ternary InGaSb Crystals by Defect Engineering via Point Defects and Microscale Compositional Segregations

et al. 2019

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Thermoelectric power generators require semiconductor materials with controlled phonon and free charge carrier transport properties. This could be achieved by changing their molecular and lattice dynamics through introducing/ controlling structural imperfections (defects engineering). The structural imperfections such as point defects and compositional segregations in a multicomponent alloy are observed experimentally, and their impact on electron and phonon transport properties was explained. The thermoelectric properties of a III− V ternary alloy InGaSb was improved by the presence of point defects and compositional segregations. The compositions were segregated randomly, and they had a major impact on the phonon contribution to the thermal conductivity. The point defects affected electrical resistivity, and the Seebeck coefficient was influenced by carrier concentration. The figure of merit (ZT) of In 0.95 Ga 0.05 Sb is enhanced to 0.62 at 573 K, and it is the highest among any other reported values of binary/ternary III−V semiconductor alloys. The enhancement in the ZT of InGaSb from the viewpoints of point defects and compositional segregations are explained. This experimental defect engineering study could be helpful to understand and improve the thermoelectric properties of many other crystalline materials.

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Investigation of directionally solidified InGaSb ternary alloys from Ga and Sb faces of GaSb(111) under prolonged microgravity at the International Space Station

Cited by 12 publications

References 27 publications

Role of Oxygen and Fluorine in Passivation of the GaSb(111) Surface Depending on Its Termination

Role of Oxygen and Fluorine in Passivation of the GaSb(111) Surface Depending on Its Termination

Engineering of the band gap and optical properties of In_xGa_1−x(As/Sb) via across composition alloying for solar cell applications using density functional theory-based approaches

An Approach to Optimize the Thermoelectric Properties of III–V Ternary InGaSb Crystals by Defect Engineering via Point Defects and Microscale Compositional Segregations

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Investigation of directionally solidified InGaSb ternary alloys from Ga and Sb faces of GaSb(111) under prolonged microgravity at the International Space Station

Cited by 12 publications

References 27 publications

Role of Oxygen and Fluorine in Passivation of the GaSb(111) Surface Depending on Its Termination

Role of Oxygen and Fluorine in Passivation of the GaSb(111) Surface Depending on Its Termination

Engineering of the band gap and optical properties of InxGa1−x(As/Sb) via across composition alloying for solar cell applications using density functional theory-based approaches

An Approach to Optimize the Thermoelectric Properties of III–V Ternary InGaSb Crystals by Defect Engineering via Point Defects and Microscale Compositional Segregations

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Engineering of the band gap and optical properties of In_xGa_1−x(As/Sb) via across composition alloying for solar cell applications using density functional theory-based approaches