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A new approach to β-Ga 2 O 3 single crystal growth was studied, using the vertical Bridgman (VB) method in ambient air, while measuring the β-Ga 2 O 3 melting temperature and investigating the effects of crucible composition and shape. β-Ga 2 O 3 single crystals 25 mm in diameter were grown in platinum–rhodium alloy crucibles in ambient air, with no adhesion of the crystals to the crucible wall. Single crystal growth without a crystal seed was realized by (100) faceted growth with a growth direction perpendicular to the (100) faceted plane. [ABSTRACT FROM AUTHOR]

A new technique is proposed in the traditional vertical Bridgman growth of sapphire crystals, in which thin-neck formation follows the initial seeding. Low-angle grain boundaries generated at the periphery of the seeding interface were eliminated at the thin neck, and the c-axis sapphire crystals with main bodies free from low-angle grain boundaries were grown. [ABSTRACT FROM AUTHOR]

Abstract: The growth of sapphire by the traditional vertical Bridgman (VB) method was studied by using various shapes of seed crystals and tungsten (W) crucibles shaped to match the seeds. Approximately 2-in. diameter, c-axis sapphire single crystals were reproducibly grown from three kinds of seed: thin, tapered and full diameter. Factors relating seed type to single-crystal growth are discussed, including the reproducibility of seeding processes, and the generation and elimination of low-angle grain boundaries (LAGBs). What was learned facilitated the subsequent growth of large-diameter, 3-, 4- and 6-in., c-axis single-crystal sapphires from full-diameter seeds. [Copyright &y& Elsevier]

• 50 mm-diameter Sn-doped (0 0 1) β-Ga 2 O 3 crystals were grown in the VB furnace with ambient air. • Dislocation densities was widely distributed across a wafer from 100 to 2000/cm2. • FWHM values was also widely distributed across a wafer from 10 to 50 arcsec. • A carrier density of 3.6 × 1018/cm3 were obtained from a 0.1 mol% Sn-doped crystal. • The obtained (0 0 1) n-type wafers might be useful for epitaxial growth substrate. 50 mm-diameter Sn-doped β-Ga 2 O 3 crystals with growth orientation perpendicular to (0 0 1) plane were grown with the newly-developed resistance heating vertical Bridgeman furnace using platinum–rhodium alloy crucibles in ambient air. Weak low angle grain boundaries and several small grains were detected on the both-side mirror-polished 50 mm-diameter (0 0 1) wafer, using high resolution refraction x-ray topography. However, no imperfections were observed over the whole wafer area when using crossed polarizer analysis. Measured values of both the full width at half maximum and the dislocation densities were widely distributed in the wafer, ranging from 10 to 50 arcsec and 100 to 2000 /cm2 respectively with no distinctive correlations among them. The Sn-doped crystals with concentrations ranging from 5 × 1017 to 5 × 1018 atom/cm3 could be grown by Sn-doping in a range from 0.05 to 0.1 mol%, and (0 0 1) oriented, 50 mm-diameter n-type oxide semiconductor wafers with a carrier density of 3.6 × 1018 /cm3, a mobility of 60 cm2/Vsec and a resistivity of 0.03 Ω-cm, were obtained from a 0.1 mol% Sn-doped crystal. [ABSTRACT FROM AUTHOR]

A resistance heating vertical Bridgeman (VB) furnace able to maintain high temperatures up to 1830 °C in ambient air was developed to suppress weight loss of both the crucible and raw material Ga 2 O 3. Large-size 50 mm diameter β-Ga 2 O 3 crystals with a growth orientation perpendicular to (1 0 0) plane were grown by the VB growth process in platinum-rhodium alloy crucibles using this furnace. The total weight loss during a VB growth run is very small, amounting to less than 1% of the total weight of the platinum-rhodium alloy crucible and the Ga 2 O 3 raw material. [ABSTRACT FROM AUTHOR]

Morphologies of metallic inclusions observed in sapphire crystals grown by the vertical Bridgman (VB) technique using a tungsten (W) crucible were investigated. Square- or hexagonal-shaped inclusions 2-5 µm in size were observed in sapphire crystals around the interface between the seed and the grown crystal. It was found that such inclusions consisted of W metal used for the crucible. The morphology of some of the inclusions reflects a rhombic dodecahedron which is based on the cubic structure of W and is surrounded by {110} faces. It is probable that inclusions form in the sapphire melt during the crystal growth process, and then sink in the melt to the growth interface due to the high density of W. [ABSTRACT FROM AUTHOR]