Growth of bulk β-Ga2O3 crystals from melt without precious-metal crucible by pulling from a cold container

Abstract

We report the growth of bulk β-Ga2O3 crystals based on crystal pulling from a melt using a cold container without employing a precious-metal crucible. Our approach, named oxide crystal growth from cold crucible (OCCC), is a fusion between the skull-melting and Czochralski methods. The absence of an expensive precious-metal crucible makes this a cost-effective crystal growth method, which is a critical factor in the semiconductor industry. An original construction 0.4–0.5 MHz SiC MOSFET transistor generator with power up to 35 kW was used to successfully grow bulk β-Ga2O3 crystals with diameters up to 46 mm. Also, an original diameter control system by generator frequency change was applied. In this preliminary study, the full width at half maximum of the X-ray rocking curve from the obtained β-Ga2O3 crystals with diameters ≤ 46 mm was comparable to those of β-Ga2O3 produced by edge-defined film fed growth. Moreover, as expected, the purity of the obtained crystals was high because only raw material-derived impurities were detected, and contamination from the process, such as insulation and noble metals, was below the detection limit. Our results indicate that the OCCC technique can be used to produce high-purity bulk β-Ga2O3 single crystalline substrate.

Electrical properties of unintentionally doped β-Ga2O3 (010) thin films grown by a low-pressure hot-wall metalorganic chemical vapor deposition

“…Another important material feature of β-Ga 2 O 3 is that bulk single crystals can be synthesized by various melt growth methods such as floating zone, 9) Czochralski, 10,11) edge-defined film-fed growth, 12) vertical Bridgman, 13,14) and crucible-less bulk melt growth. 15) These physical properties suggest the great potential of β-Ga 2 O 3 for various applications to power electronics and harsh environment electronics. Taking advantage of the availability of high-quality β-Ga 2 O 3 epitaxial substrates, vertical Ga 2 O 3 FETs and diodes with homoepitaxial drift layers have been energetically developed.…”