Symmetry Breaking in Twisted Bilayer CVD-Grown Single-Crystal MoS ₂ for High-Performance Polarization-Sensitive Photodetection

Endowing wafer-level-manufactured two-dimensional (2D) materials with anisotropy to enable polarization-sensitive photodetection applications holds significant research importance. On the one hand, although many kinds of 2D semiconductors deliver good polarization-sensitivity, most of them do not realize the wafer-scale growth due to the rare precursor, complex fabrication, or instability in ambient. On the other hand, molybdenum disulfide (MoS 2 ) has the possibility to grow as large as 12 in., but it is optically isotropic and does not exhibit polarization-sensitivity. It is a significant challenge to break its symmetry and enable future polarization-sensitive focal-plane-array photodetection. Herein, MoS 2 with different twisted angles was successfully prepared, and its optical, photoelectronic, and polarization properties were investigated, and its potential in polarization-sensitive photodetection was explored. First, the nonuniform interlayer coupling and local strain generated by lattice relaxation in twisted bilayer MoS 2 (TBL-MoS 2 ) were characterized from the structure, and the broken symmetry of TBL-MoS 2 was demonstrated. Besides, TBL-MoS 2 exhibited polarization-sensitive properties, the polarization ratio first increased and then decreased as the twisted angle decreases from 18.3° to 1.7°, reaching an extreme value of 1.40@650 nm at 2.2°. The anisotropic and polarization-sensitive photodetection properties exhibited by TBL-MoS 2 provide crucial evidence for exploring applications of isotropic 2D materials in polarization detection.