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 (MoS2) 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, MoS2 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 MoS2 (TBL-MoS2) were characterized from the structure, and the broken symmetry of TBL-MoS2 was demonstrated. Besides, TBL-MoS2 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-MoS2 provide crucial evidence for exploring applications of isotropic 2D materials in polarization detection.