Micro-Raman spectroscopy of bending stresses in -Ga₂O₃(001) wafer

To develop high-performance semiconductor devices, it is critical to study the relationship between stress and phonon frequency shifts. We used micro-Raman spectroscopy on a beta-Ga2O3(001) wafer to better understand the relationship. We applied tensile stress to a sample along the [010] direction by bending in the direction normal to the (001) plane. The unbent sample's Raman spectrum showed 9A(g) + 4B(g) phonon modes, which are allowed in the experimental geometry. Although some of these peaks monotonically shifted to the lower frequency side as tensile stress increased, each phonon mode showed a different peak shift. The stress potential values for each phonon mode obtained from our results showed different trends from those of the theoretically calculated values reported in previous studies, suggesting that bending stresses on the (001) plane cause stresses in the (010) plane and along the [010] direction.