Preprint: Growing ScB₂ Crystals at Ambient Pressure for AlGaN Power Electronics
Crystal boules grown by floating zone at ambient pressure.
Our APEX team is pleased to share new work on the growth of scandium diboride (ScB₂) crystals, led by Satya K. Kushwaha (Johns Hopkins University and the University of North Texas) with senior author MVS Chandrashekhar (Morgan State University). Ultrawide bandgap semiconductors such as AlGaN could enable power electronics that operate at higher voltages and temperatures than today's devices, but they are held back by the lack of a substrate that matches their crystal structure and also conducts electricity and heat well. ScB₂ is a promising candidate, yet it has been difficult to grow because scandium evaporates near its melting point, which has typically required high-pressure equipment.
Together, we show that high-quality single crystals can be grown at ambient pressure using a floating zone approach with a boron-rich flux. Our combined electron microscopy, x-ray, and spectroscopy measurements indicate single-domain crystals of good structural quality, and they point to the next steps: growing AlGaN on these substrates and examining point defects at the atomic scale. This result reflects the collaborative strength of APEX, and I am grateful to our partners at Johns Hopkins, Morgan State, NLR, Argonne, Towson, and the University of Virginia.