Single-Crystal Growth of ZnO:Ga by the Traveling-Solvent Floating-Zone Method

Abstract

Transparent and blue ZnO:Ga (GZO) single crystals have been grown by the traveling-solvent floating-zone technique using the solvent B2O3 + MoO3 + Nb2O5. The crystals were typically 9–14 mm in diameter and 46–120 mm in length. The largest one was Φ12 mm × 120 mm in size. All GZO crystals were grown along the <001> direction. The growth rate was 0.3–0.5 mm/h, which was far faster than 0.1 mm/day of that grown by the hydrothermal method. The crystalline quality has been characterized by single crystal X-ray diffraction and X-ray rocking curve measurements. Ga substituted on Zn-site and was saturated at about 0.5 wt % of Ga2O3 addition. The GZO crystal doped with 0.5 wt % Ga2O3 has the lowest electrical resistivity of 1.083 × 10–3 Ω·cm and the highest carrier concentration of 1.78 × 1020 cm–3.

A homogeneity study on (Ce,Gd)3Ga2Al3O12 crystal scintillators grown by an optical floating zone method and a traveling solvent floating zone method

“…In addition, the stable solid–liquid interface and the high temperature gradient near the molten zone can maintain a higher crystallization driving force. 37,41…”

“…It revealed a different solidification rate between the two methods although their growth rates are the same during the crystal growth process. We suspect that since the solvent would not penetrate deeply into the feed or seed rod by the capillarity action along the grain boundaries, 37 a clear and smooth solid-liquid interface could thereby be kept during the process of dissolving the feed rod in the solvent; the mass transfer rate of the diffusion layer at the solid-liquid interface is slow 43 and the exchange of Ce 3+ between the melt of the feed and seed rod may be hindered by the clear interface of the solvent, and thus the solid solution of Ce 3+ was limited accordingly. Fig.…”

“…33,35 Recently, Ce-doped Gd 2 Si 2 O 7 and ZnO:Ga crystal scintillators were also successfully grown by the TSFZ method. 36,37 However, the application of the TSFZ method in scintillation crystals is still comparatively rare.…”