Layered metal thiophosphates with a general formula MPX3 (M is a group VIIB or VIII element and X is a chalcogen) have emerged as a novel member in a two-dimensional (2D) family with fascinating physical and chemical properties. Herein, the photoelectric performance of the few-layer MnPSe3 was studied for the first time. The multilayer MnPSe3 shows p-type conductivity and its field-effect transistor delivers an ultralow dark current of about 0.1 pA. The photoswitching ratio reaches ∼103 at a wavelength of 375 nm, superior to that of other thiophosphates. A responsivity and detectivity of 392.78 mA/W and 2.19 × 109 Jones, respectively, have been demonstrated under irradiation of 375 nm laser with a power intensity of 0.1 mW/cm2. In particular, the photocurrent can be remarkably increased up to 30 times by integrating a layer of Au nanoparticle array at the bottom of the MnPSe3 layer. The metal-semiconductor interfacial electric field and the strain-induced flexoelectric polarization field caused by the underlying nanorugged Au nanoparticles are proposed to contribute together to the significant current improvement.
Keywords: 2D material; MnPSe3; flexoelectricity; p-type semiconductor; phototransistor.