Dark Current Mechanisms and Suppression Strategies for Infrared Photodetectors Based on Two-Dimensional Materials

Narrow-bandgap 2D materials and semimetals, for example, graphene, black phosphorus (BP), tellurium (Te), and some novel transition metal dichalcogenides (TMDs), have been demonstrated to be promising building blocks for constructing next-generation state-of-the-art infrared (IR) photodetectors. However, these devices suffer from a significant dark current, primarily attributed to the intrinsic thermal excitation-induced high carrier concentration. Suppressing the dark current is an essential issue in pursuing higher specific detectivity of IR photodetectors. Here, the authors demonstrate recent advances in suppressing dark current for 2D IR photodetectors. First, a brief insight into the dark current composition and mechanisms of 2D IR photodetectors is illustrated. Then, the varied band alignment for blocking dark current by the interfacial barrier is discussed. Next, localized electric field modulation by applying a gate voltage and ferroelectric materials is discussed. This method can effectively tune the concentration and distribution of carriers in the device conductive channel. Following that, interfacial engineering is summarized, by which interfacial defects can be passivated and interlayer defect-induced dark current can be suppressed. Finally, the challenges and an outlook are delivered for developing state-of-the-art IR photodetectors. Exploring the crucial role of dark current in 2D infrared optoelectronics, this review discusses the dark current generation mechanisms and summarizes the main methods for suppressing dark current in 2D infrared photodetectors. Diverse device structures and working mechanisms based on various dark current suppression strategies are discussed. Conclusions and future perspectives are delivered as a guideline for this thriving field.image