Novel Crystal Technology (NCT), a global leader in Gallium Oxide (Ga₂O₃) technology, has successfully grown the first 6-inch Ga₂O₃ single crystal using the advanced Vertical Bridgman (VB) technique. This achievement marks a significant step forward in NCT’s efforts to deliver larger, high-quality semiconductor wafers for Ga₂O₃-based power devices.

The VB technique offers several advantages over NCT’s existing Edge-defined Film-fed Growth (EFG) method. By growing the crystal in a cylindrical shape, VB significantly reduces costs associated with substrate cutting. Additionally, it allows for production of substrates in various crystalline orientations, unrestricted by limitations imposed by crystal anisotropy. Furthermore, the controlled thermal environment of VB growth leads to superior crystal quality with minimal defects, compared to EFG. Finally, dopant uniformity within the substrate is expected to improve, aligning with industry standards for other semiconductors like silicon.

(Figure 1: Ga₂O₃ bulk crystals)

NCT carried out a comparative evaluation between VB and EFG crystals with National Institute of Advanced Industrial Science and Technology (AIST) revealed a dramatic improvement in crystal quality. Synchrotron radiation X-ray topography analysis confirmed minimal defects in the VB-grown crystal, compared to the high density of defects observed in the EFG-grown crystal. This clearly demonstrates the superiority of the VB technique for producing high-quality Ga₂O₃ substrates.

(Figure 2: Synchrotron radiation X-ray topography images)

Ga₂O₃ is a promising material for power electronics due to its ability to significantly reduce power loss compared to commonly used Silicon Carbide (SiC) in high-voltage applications, like electric vehicles and renewable energy systems. Its wide bandgap characteristics hold immense potential for energy conservation and CO₂ emission reduction.

Established in 2015, NCT manufactures 2-inch and 100 mm gallium oxide (Ga₂O₃) substrates and epi-wafers for power devices. These are commercially available and used by universities, institutes, and power device companies worldwide. NCT currently supplies thousands of these substrates annually to support research and development efforts.

NCT is actively developing larger substrates such as 6-inch. Beyond substrates, NCT has a vision for broader Ga₂O₃ device production. They are already offering samples of their first Ga₂O₃ Schottky Barrier Diode, with qualification tests expected to be completed in September 2024.

The development of the Vertical Bridgman growth technique for Ga₂O₃ single crystals was initiated by Shinshu University, successfully achieving growth of 2-inch and 4-inch crystals. NCT acquired and extended their techniques to enable larger diameter crystal development. This research and development program was partially funded by the Adaptable and Seamless Technology Transfer Program through Target Driven R&D (A-STEP) of the Japan Science and Technology Agency (JST).