【Member Papers】The research team of Zhejiang University Science and Technology Innovation Center realized the growth of 4-inch Mg-doped Gallium Oxide single crystal and substrate by casting method

      Recently, a research team from Zhejiang University published an article in the academic Journal of Alloys and Compounds titled “Characteristics of 4-inch (100) oriented Mg-doped β-Ga₂O₃ bulk single crystals grown by a casting method” (Characteristics of 4-inch (100) oriented Mg-doped β-Ga₂O₃ bulk single crystals grown by casting method).

Abstract

      As an oxide semiconductor material, β-phase Gallium Oxide has an ultra-wide band gap of ~4.8 eV. Its unique properties, including a high breakdown field of up to 8 MV/cm and a Baliga figure-of-merit of 3444, endow β-Ga₂O₃ with great potential for high-power field effect transistors and high-performance Schottky Barrier Diodes. The growth of high-quality 4-inch-diameter Mg-doped semi-insulating β-Ga₂O₃ single crystal and substrate has been achieved for the first time by the casting method. The crystal structure and basic electrical and optical properties of (100) oriented Mg-β-Ga₂O₃ wafers were characterized. The XRD rocking curves (400) sampled at five points have sharp and symmetrical peaks, and FWHM is less than 40 ", showing a high crystal quality. The polished wafers measured an average resistivity of 3.5 × 10¹² Ω∙cm at room temperature and demonstrated high uniformity, compared to the 0.333Ω ∙cm resistivity of the unintentionally doped (UID) sample, where Mg doping showed excellent semi-insulating properties. This study demonstrates the promise of the casting method for efficient, low-cost, large-size growth of β-Ga₂O₃ single crystals with tunable resistivity.

Figure 1. 4-inch diameter β-Ga₂O₃ (a) ingot grown by casting and (b) corresponding polished substrate.

Figure 2. HRXRD pattern of 4-inch Mg:β-Ga₂O₃ substrate.

Figure 3. (a) In-plane resistivity distribution of a 4-inch Mg-doped-β-Ga₂O₃ wafer,  (b) The resistivity of Mg-doped β-Ga₂O₃ wafer (orange circle) and UID β-Ga₂O₃ substrate (purple circle) compared to the resistivity of crystals grown by the Z. Galazka, CZ and T. Onuma, OFZ

Paper Link：https://doi.org/10.1016/j.jallcom.2024.174162