Strain-enhanced polarization sensitivity in β-Ga₂O₃ photodetector

Polarization-sensitive photodetection and imaging have great application value in fields such as polarization division multiplexing optical communication, remote sensing, near-field imaging and military monitoring. Pursuing a high polarization ratio has always been the research hotspot in polarization-sensitive photodetectors. In this paper, we report a compression strain enhanced polarization ratio in β-gallium oxide (β-Ga₂O₃) single crystal flake. A rigorous crystallographic analysis confirmed its high crystalline quality and orientation. Angle-resolved polarization Raman spectroscopy (ARPRS) was adopted to study the anisotropy of its optical properties. Extensive ARPRS measurements and theoretical calculation consistently demonstrate the strong optical anisotropy in the high-quality β-Ga₂O₃ flake. A polarization ratio of 0.96 was obtained in the flat β-Ga₂O₃ flake. Furthermore, mechanical strain of ±0.7% was introduced into β-Ga₂O₃. An increased polarization ratio of 0.98 was achieved in the case of 0.7% compression strain, which is, to the best of our knowledge, the highest value for UVC polarization-sensitive photodetectors. That corresponds to an improved polarization rejection ratio of 100. This work proposed a new path towards improving polarization sensitivity by applying strain engineering in the active material.