【Substrate Papers】Anisotropic mechanical properties of β-Ga₂O₃ single crystals grown by optical floating zone technique

      Researchers from the Anna University have published a dissertation titled "Anisotropic mechanical properties of β-Ga₂O₃ single crystals grown by optical floating zone technique" in Materials Science in Semiconductor Processing.

Abstract

      Single crystals of β-Ga₂O₃ were grown by the Optical Floating Zone technique. Diamond wire cutting was optimized to prepare β-Ga₂O₃ wafers with a thickness of 1.5 mm. The material removal mechanism during polishing followed by both (100) and (010) surfaces was observed by an optical microscope. Hardness measurements on as-grown and annealed samples indicate hardness values in the range of ∼5.63 to ∼5.16 GPa for (100) orientation and ∼7 to ∼6.41 GPa for (010) orientation. The reason for this difference in hardness values and material removal mechanism of (100) and (010) has been accounted for by the atomic arrangement, surface energy and bonding. An appropriate removal system was presented with the diamond as an abrasive. Studies on the interaction between the abrasive and β-Ga₂O₃ wafers were carried out and Transmission Electron Microscopic images of abrasives on each step of the polishing are recorded. Efforts were made to obtain a polishing recipe for both orientations towards optimization of the recipe. The material removal trend was reported with the use of an optical microscope at each step of polishing. Atomic force Microscope images of the fully polished β-Ga₂O₃ wafers show the uniformity of the surfaces with roughness values ∼1 nm. Schottky Barrier Diodes were fabricated using wafers polished by conventional and optimized polishing recipes. The diodes were electrically characterized and the effect of polishing on device performance was reported.

DOI：

https://doi.org/10.1016/j.mssp.2025.109600