Strain Tune Suspended MoS2 for Polarization Photodetection

In situ modulation of molybdenum disulfide (MoS2) structure and breaking its isotopic optical property are crucial for fabricating high-performance multidimensional photodetectors. However, achieving this remains a challenge. Herein, by introducing a cavity in the channel, the strain tunable suspended MoS2 phototransistor is fabricated. By pumping the environment, a pressure difference between the environment and cavity is generated, inducing strain in the MoS2. Simulation reveals the strain can be tuned up to 0.598% by changing environment pressure. The electrical and photoelectrical properties exhibit significant tuning in response to pressure. During this experiment, the conductance of MoS2 under different pressures shows considerable differentiation between 50 and 100 kPa. As light wavelength decreases, the trend of photocurrent increasing under different pressure becomes more apparent. The differential conductance-voltage curve of different wavelengths at 10 Pa is more dispersed than that at 101 kPa. Those results demonstrate the coupling effect between light and strain. Interestingly, the symmetric photoelectrical property of MoS2 can be broken, resulting in polarization detection. At a pressure of 60 kPa, the dichroic ratio reaches 1.38, similar to intrinsic anisotropic two-dimensional materials. This can be attributed to the breaking of symmetric structure caused by strain.