Characteristics of 4-inch (100) oriented Mg-doped β-Ga2O3 bulk single crystals grown by a casting method

In this Letter, 4-inch diameter (100) magnesium-doped monoclinic gallium oxide (Mg:β-Ga2O3) bulk single crystals were grown by a casting method. The crystallographic structure, electrical, optical properties, and defects of Mg-doped β-Ga2O3 was thoroughly investigated by XRD rocking curves, AFM, non-contact resistivity measurements, XPS, optical transmission spectra, Raman spectroscopy, and defect-selective chemical etching processes. Comparing to the UID samples, the larger bandgap of 4.75 eV and high resistivity of 3.50×1012 Ω∙cm indicated Mg a proper dopant for fabricating semi-insulating β-Ga2O3 substrates which could be preferred for power devices. XPS spectra exhibited the ability of Mg2+ to inhibit the formation of oxygen vacancy defects in the crystals. Meanwhile, the high crystalline quality and low density of defects demonstrated the advantages of casting method in achieving large-size and high-quality β-Ga2O3 bulk single crystals with changeable resistivity. This result indicates a high potential to achieve high-quality and low-cost substrates which satisfy the requirement of high-performance power electronic devices.