Growth Measures to Achieve Bulk Single Crystals of Transparent Semiconducting and Conducting Oxides

Galazka, Zbigniew

doi:10.1016/b978-0-444-63303-3.00006-7

Cited by 4 publications

(7 citation statements)

References 138 publications

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“…The first three endothermal peaks are connected with a mass loss that is monotonous but changes in rate: E.g. at point (1) where the DTA curve is less endothermal, also the TG curve is flatter. Obviously the reaction rate is smaller at this point, and consequently mass loss is reduced, in agreement with a smaller endothermal effect.…”

Section: Resultsmentioning

confidence: 99%

“…The technological interest in developing transparent conducting oxide (TCO) or transparent semiconducting oxide (TSO) materials has seen a dramatic increase in recent years. Established TCO's, such as CdO, β-Ga 2 O 3 , In 2 O 3 , SnO 2 and ZnO [1,2] are n-type semiconductors in which electrons act as main charge carriers. However, in semiconductor electronics, p-n-junctions are of major importance where hole conduction is required in the p-type parts [3].…”

Section: Introductionmentioning

confidence: 99%

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Thermodynamic investigations on the growth of CuAlO2 delafossite crystals

Wolff

Klimm

Siche

2018

Journal of Solid State Chemistry

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Simultaneous differential thermal analysis (DTA) and thermogravimetric (TG) measurements with copper oxide/aluminum oxide mixtures were performed in atmospheres with varying oxygen partial pressures and with crucibles made of different materials. Only sapphire and platinum crucibles proved to be stable under conditions that are useful for the growth of CuAlO 2 delafossite single crystals. Then the ternary phase diagram Al 2 O 3 -CuO-Cu and its isopleth section Cu 2 O-Al 2 O 3 were redetermined. Millimeter sized crystals could be obtained from copper oxide melts with 1-2 mol-% addition of aluminum oxide that are stable in platinum crucibles held in oxidizing atmosphere containing 15-21% oxygen.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Thermodynamic investigations on the growth of CuAlO2 delafossite crystals

Wolff

Klimm

Siche

2018

Journal of Solid State Chemistry

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“…Besides, r-GeO 2 has a remarkably high Vickers hardness number of ∼2500, 25 which is larger than that of sapphire, and it is exceeded only by materials which are synthesized at a very high pressure, such as stishovite r-SiO 2 . 26 Another beneficial property of GeO 2 is the remarkably low melting point (1115 °C) as compared to the established WBG oxide semiconductors ZnO (1975 °C), 27 β-Ga 2 O 3 (1820 °C), 28 In 2 O 3 (1950 °C), 29 and SnO 2 (>2100 °C). 30 However, the GeO 2 melt is extremely viscous, and upon cooling, it solidifies as an amorphous glass.…”

Section: Introductionmentioning

confidence: 99%

“…Another beneficial property of GeO 2 is the remarkably low melting point (1115 °C) as compared to the established WBG oxide semiconductors ZnO (1975 °C), β-Ga 2 O 3 (1820 °C), In 2 O 3 (1950 °C), and SnO 2 (>2100 °C) . However, the GeO 2 melt is extremely viscous, and upon cooling, it solidifies as an amorphous glass.…”

Section: Introductionmentioning

confidence: 99%

Shallow Valence Band of Rutile GeO₂ and P-type Doping

et al. 2020

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GeO2 has an α-quartz-type crystal structure with a very wide fundamental band gap of 6.6 eV and is a good insulator. Here we find that the stable rutile-GeO2 polymorph with a 4.6 eV band gap has a surprisingly low ~6.8 eV ionization potential, as predicted from the band alignment using first-principles calculations. Because of the short O-O distances in the rutile structure containing cations of small effective ionic radii such as Ge 4+ , the antibonding interaction between O 2p orbitals raises the valence band maximum energy level to an extent that hole doping appears feasible. Experimentally, we report the flux growth of 1.5 × 1.0 × 0.8 mm 3 large rutile GeO2 single crystals and confirm the thermal stability for temperatures up to 1021 ± 10 o C. X-ray fluorescence spectroscopy shows the inclusion of unintentional Mo impurities from the Li2O-MoO3 flux, as well as the solubility of Ga in the r-GeO2 lattice as a prospective acceptor dopant. The resistance of the Ga-and Mo-co-doped r-GeO2 single crystals is very high at room temperature, but it decreases by 2-3 orders of magnitude upon heating to 300 o C, which is attributed to thermally-activated p-type conduction.

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“…Exploration of these materials for electronics is exciting due to two very advantageous features as compared to established TOSs. First, the 1115 °C melting point of GeO 2 (trigonal, P 3 1 21) is remarkably low as compared to the neighboring group IV oxides such as SiO 2 (1710 °C), SnO 2 (>2100 °C), and β-Ga 2 O 3 (1820 °C). The low melting temperature makes single crystal growth from the melt significantly easier.…”

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confidence: 99%

Crystal Structure Built from a GeO₆–GeO₅ Polyhedra Network with High Thermal Stability: β–SrGe₂O₅

Niedermeier

Yamaura

et al. 2019

ACS Appl. Electron. Mater.

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By tackling the challenge of extending transparent oxide semiconductors to Ge-based oxides, we have found a not-yet-reported crystal structure, named β-SrGe2O5, which is composed of edge-sharing GeO6 octahedra interconnected by GeO5 bipyramids. Single crystals were successfully grown by the high-pressure flux method. β-SrGe2O5 has a band gap of 5.2 eV and a dispersive conduction band with an effective mass as small as 0.34 times the electron rest mass, which originates from the edge-sharing GeO6 octahedra network. Although known compounds with octahedral GeO6 coordination are commonly unstable at atmospheric pressure and elevated temperatures, β-SrGe2O5 exhibits thermal stability up to 700 o C.

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Growth Measures to Achieve Bulk Single Crystals of Transparent Semiconducting and Conducting Oxides

Cited by 4 publications

References 138 publications

Thermodynamic investigations on the growth of CuAlO2 delafossite crystals

Thermodynamic investigations on the growth of CuAlO2 delafossite crystals

Shallow Valence Band of Rutile GeO₂ and P-type Doping

Crystal Structure Built from a GeO₆–GeO₅ Polyhedra Network with High Thermal Stability: β–SrGe₂O₅

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Growth Measures to Achieve Bulk Single Crystals of Transparent Semiconducting and Conducting Oxides

Cited by 4 publications

References 138 publications

Thermodynamic investigations on the growth of CuAlO2 delafossite crystals

Thermodynamic investigations on the growth of CuAlO2 delafossite crystals

Shallow Valence Band of Rutile GeO2 and P-type Doping

Crystal Structure Built from a GeO6–GeO5 Polyhedra Network with High Thermal Stability: β–SrGe2O5

Contact Info

Product

Resources

About

Shallow Valence Band of Rutile GeO₂ and P-type Doping

Crystal Structure Built from a GeO₆–GeO₅ Polyhedra Network with High Thermal Stability: β–SrGe₂O₅