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Photodetectors are essential optoelectronic devices that play a critical role in modern technology by converting optical signals into electrical signals, which are one of the most important sensors of the informational devices in current 'Internet of Things' era. Two-dimensional (2D) material-based photodetectors have excellent performance, simple design and effortless fabrication processes, as well as enormous potential for fabricating highly integrated and efficient optoelectronic devices, which has attracted extensive research attention in recent years. The introduction of spontaneous polarization ferroelectric materials further enhances the performance of 2D photodetectors, moreover, companying with the reduction of power consumption. This article reviews the recent advances of materials, devices in ferroelectric-modulated photodetectors. This review starts with the introduce of the basic terms and concepts of the photodetector and various ferroelectric materials applied in 2D photodetectors, then presents a variety of typical device structures, fundamental mechanisms and potential applications under ferroelectric polarization modulation. Finally, we summarize the leading challenges currently confronting ferroelectric-modulated photodetectors and outline their future perspectives. [ABSTRACT FROM AUTHOR]

Photodetectors with two-dimensional (2D) materials on a SiO 2 /Si substrate have been extensively explored. However, these photodetectors often suffer from a large gate voltage and relatively low photoresponsivity due to the low efficiency light absorption of 2D materials. Here, we develop a MoS 2 photodetector based on the Al 2 O 3 /ITO (indium tin oxide)/SiO 2 /Si substrate with ultrahigh photoresponsivity of 2.7 × 10 4 A W -1 . Most of the incident light is reflected by the interface of stacked Al 2 O 3 /ITO/SiO 2 substrate, which significantly increases the light absorption of 2D materials. With the help of thinner and high-κ Al 2 O 3 dielectric, the current ON/OFF ratio could exceed 10 9 with a gate voltage no more than 2 V. Enhanced gate regulation also brings about a relatively high mobility of 84 cm 2 V -1 s -1 and subthreshold swing of 104 mV dec -1 . Additionally, two different photocurrent generation mechanisms have also been revealed by tuning the gate voltage. The reflection-enhancement substrate assisted MoS 2 photodetector provides a new idea for improving the performance of 2D material photodetectors, which can be perfectly combined with other methods.

In recent years, the electrical characteristics of WSe 2 field-effect transistors (FETs) have been widely investigated with various dielectrics. Among them, being able to perfectly tune the polarity of WSe 2 is meaningful and promising work. In this work, we systematically study the electrical properties of bilayer WSe 2 FETs modulated by ferroelectric polymer poly(vinylidenefluoride-co-trifluoroethylene) (P(VDF-TrFE)). Compared to traditional gate dielectric SiO 2 , the P(VDF-TrFE) can not only tune both electron and hole concentrations to the same high level, but also improve the hole mobility of bilayer WSe 2 to 265.96 cm 2 V -1 s -1 under SiO 2 gating. Its drain current on/off ratio is also improved to 2 × 10 5 for p-type and 4 × 10 5 for n-type driven by P(VDF-TrFE). More importantly, the ambipolar behaviors of bilayer WSe 2 are effectively achieved and maintained because of the remnant polarization field of P(VDF-TrFE). This work indicates that WSe 2 FETs with P(VDF-TrFE) gating have huge potential for complementary logic transistor applications, and paves an effective way to achieve in-plane p-n junctions.

Two-dimensional materials are promising candidates for electronic and optoelectronic applications. MoTe2 has an appropriate bandgap for both visible and infrared light photodetection. Here we fabricate a high-performance photodetector based on few-layer MoTe2. Raman spectral properties have been studied for different thicknesses of MoTe2. The photodetector based on few-layer MoTe2 exhibits broad spectral range photodetection (0.6-1.55 μm) and a stable and fast photoresponse. The detectivity is calculated to be 3.1 × 10(9) cm Hz(1/2) W(-1) for 637 nm light and 1.3 × 10(9) cm Hz(1/2) W(-1) for 1060 nm light at a backgate voltage of 10 V. The mechanisms of photocurrent generation have been analyzed in detail, and it is considered that a photogating effect plays an important role in photodetection. The appreciable performance and detection over a broad spectral range make it a promising material for high-performance photodetectors.