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Non-centrosymmetric material systems can generate spontaneous photocurrent without a p-n junction under uniform illumination, which is known as the bulk photovoltaic effect (BPVE). It has garnered significant attention for its application potential in the fields of energy harvesting and photoelectric detection. In this study, we report the BPVE observed in two-dimensional ferroelectric α-In2Se3 multilayer flakes. The reversal in spontaneous photocurrent polarity is observed and associated with the out-of-plane ferroelectric polarization direction. The spontaneous photocurrent originating from the shift current is also polarization-sensitive. The amplitude of spontaneous photocurrent is further increased by one order of magnitude through vacuum annealing. Our results provide a further application potential for new-generation photodetectors based on BPVE with low power consumption and multi-dimensional optoelectronic detection. [ABSTRACT FROM AUTHOR]

Non-centrosymmetric material systems can generate spontaneous photocurrent without a p-n junction under uniform illumination, which is known as the bulk photovoltaic effect (BPVE). It has garnered significant attention for its application potential in the fields of energy harvesting and photoelectric detection. In this study, we report the BPVE observed in two-dimensional ferroelectric α-In2Se3 multilayer flakes. The reversal in spontaneous photocurrent polarity is observed and associated with the out-of-plane ferroelectric polarization direction. The spontaneous photocurrent originating from the shift current is also polarization-sensitive. The amplitude of spontaneous photocurrent is further increased by one order of magnitude through vacuum annealing. Our results provide a further application potential for new-generation photodetectors based on BPVE with low power consumption and multi-dimensional optoelectronic detection. [ABSTRACT FROM AUTHOR]

With the further miniaturization and integration of multi-dimensional optical information detection devices, polarization-sensitive photodetectors based on anisotropic low-dimension materials have attractive potential applications. However, the performance of these devices is restricted by intrinsic property of materials leading to a small polarization ratio of the detectors. Here, we construct a black phosphorus (BP) homojunction photodetector defined by ferroelectric domains with ultra-sensitive polarization photoresponse. With the modulation of ferroelectric field, the BP exhibits anisotropic dispersion changes, leading an increased photothermalelectric (PTE) current in the armchair (AC) direction. Moreover, the PN junction can promote the PTE current and accelerate carrier separation. As a result, the BP photodetector demonstrates an ultrahigh polarization ratio (PR) of 288 at 1450 nm incident light, a large photoresponsivity of 1.06 A/W, and a high detectivity of 1.27 × 1011 cmHz1/2W−1 at room temperature. This work reveals the great potential of BP in future polarized light detection. Integrated polarization-sensitive photodetectors are important for sensing applications and optical communication. Here, the authors report the realization of 2D black phosphorus homojunction photodetectors defined by ferroelectric substrates, showing polarization ratios up to 288 and high responsivity in the near-infrared. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) layered materials have received significant attention owing to their unique crystal structures as well as outstanding optical and electric properties in photoelectric detection. However, most 2D materials are very sensitive to the environment. Adsorbates and traps introduced during the preparation process have a negative effect on the performance of devices based on these materials. Here, we focus on a molybdenum disulfide (MoS2) phototransistor gated by ferroelectrics, and insert a hexagonal boron nitride (h-BN) layer between MoS2 and the ferroelectric film to improve the interface. To clarify the role of h-BN in this device, two parallel devices are prepared on the same MoS2 flake. One device is covered with h-BN, while the other is in direct contact with the ferroelectric film. The electronic and optoelectronic properties of these two devices are then measured and compared. Experimental results reveal that, compared to device without h-BN, the MoS2 phototransistor with h-BN exhibits higher carrier mobility (average value: 85 cm2·V−1·s−1 and highest value: 185 cm2·V−1·s−1), larger responsivity (85 A·W−1), and larger detectivity (1.76 × 1013 Jones). Thus, this strategy is significant for the interface engineering and performance improvement of devices based on 2D materials. [ABSTRACT FROM AUTHOR]

Sensitive photodetection is crucial for modern optoelectronic technology. Two-dimensional molybdenum disulfide (MoS2) with unique crystal structure, and extraordinary electrical and optical properties is a promising candidate for ultrasensitive photodetection. Previously reported methods to improve the performance of MoS2 photodetectors have focused on complex hybrid systems in which leakage paths and dark currents inevitably increase, thereby reducing the photodetectivity. Here, we report an ultrasensitive negative capacitance (NC) MoS2 phototransistor with a layer of ferroelectric hafnium zirconium oxide film in the gate dielectric stack. The prototype photodetectors demonstrate a hysteresis-free ultra-steep subthreshold slope of 17.64 mV/dec and ultrahigh photodetectivity of 4.75 × 1014 cm Hz1/2 W−1 at room temperature. The enhanced performance benefits from the combined action of the strong photogating effect induced by ferroelectric local electrostatic field and the voltage amplification based on ferroelectric NC effect. These results address the key challenges for MoS2 photodetectors and offer inspiration for the development of other optoelectronic devices. Here, the authors report ultrasensitive negative capacitance phototransistors based on MoS2 regulated by a layer of ferroelectric hafnium zirconium oxide film to demonstrate a hysteresis-free ultra-steep subthreshold slope of 17.64 mV/dec and specific detectivity of 4.75 × 1014 cm Hz1/2 W−1 at room temperature. [ABSTRACT FROM AUTHOR]